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  • Getting the value from asp:LinkButton's CommandArgument attribute using jquery/javascript

    - by LobalOrning
    I need to get the value of the CommandArgument attribute of a LinkButton, in an asp:Repeater. I have an asp:Repeater with 2 LinkButtons whose CommandArgument I set to a value: <ItemTemplate> <tr class="odd"> <td><%#DataBinder.Eval(Container.DataItem, "batch_id")%></td> <td><%#DataBinder.Eval(Container.DataItem, "productId")%></td> <td><%#DataBinder.Eval(Container.DataItem, "serial_number")%></td> <td><%#DataBinder.Eval(Container.DataItem, "activation_card_number")%></td> <td><%#DataBinder.Eval(Container.DataItem, "transaction_amount","{0:C}")%></td> <td><%#DataBinder.Eval(Container.DataItem, "response_dt", "{0:M/d/yyyy HH:mm:ss}")%></td> <td style="text-align:center;"><%#DataBinder.Eval(Container.DataItem, "resp_process_msg")%></td> <td style="text-align:center;"><%#DataBinder.Eval(Container.DataItem, "resp_response_code")%></td> <td style="text-align:center;"><asp:LinkButton ID="lnkBtnRestageAdd" CommandName="Add" CommandArgument='<%#Eval("activation_card_number")%>' runat="server" Text="stage" class="add" OnClientClick="return false;" /></td> <td style="text-align:center;"><asp:LinkButton ID="lnkBtnRestageMinus" CommandName="Subtract" CommandArgument='<%#Eval("activation_card_number")%>' runat="server" Text="stage" class="minus" OnClientClick="return false;" /></td> </tr> </ItemTemplate> I have suppressed the PostBack with OnClientClick="return false;" so that I can pop a jQuery dialog modal when the link buttons get clicked: if (btnAdd != null) { $(".add").click(function() { $("#<%=divDialogAdd.ClientID %>").removeAttr("style"); $("#<%=divDialogAdd.ClientID %>").dialog("open"); }); } In the modal I have 2 other asp:LinkButtons, and when the 'Yes' button is clicked I do the postback like so: yesBtn.click(function() { setTimeout('__doPostBack(\'btnAdd\',\'\')', 0); //need to add a param }); What I need to do, is somehow grab the CommandArgument value from the LinkButton in the Repeater, so that I can pass that as a parametere or assign it to a hidden field. I have tried jQuery's attr(), but that only works when the attribute was set using that function as well. How can I get this value, or what other way can I go about this?

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  • What's the purpose of arrays starting with nonzero index?

    - by helios35
    I tried to find answers, but all I got was answers on how to realize arrays starting with nonzero indexes. Some languages, such as pascal, provide this by default, e.g., you can create an array such as var foobar: array[1..10] of string; I've always been wondering: Why would you want to have the array index not to start with 0? I guess it may be more familiar for beginners to have arrays starting with 1 and the last index being the size of the array, but on a long-term basis, programmers should get used to values starting with 0. Another purpose I could think of: In some cases, the index could actually represent something thats contained in the respective array-entry. e.g., you want to get all capital letters in an array, it may be handy to have an index being the ASCII-Code of the respective letter. But its pretty easy just to subtract a constant value. In this example, you could (in C) simply do something like this do get all capital letters and access the letter with ascii-code 67: #define ASCII_SHIFT 65 main() { int capital_letters[26]; int i; for (i=0; i<26; i++){ capital_letters[i] = i+ASCII_SHIFT; } printf("%c\n", capital_letters[67-ASCII_SHIFT]); } Also, I think you should use hash tables if you want to access entries by some sort of key. Someone might retort: Why should the index always start with 0? Well, it's a hell of a lot simpler this way. You'll be faster when you just have to type one index when declaring an array. Also, you can always be sure that the first entry is array[0] and the last one is array[length_of_array-1]. It is also common that other data structures start with 0. e.g., if you read a binary file, you start with the 0th byte, not the first. Now, why do some programming languages have this "feature" and why do some people ask how to achieve this in languages such as C/C++?, is there any situation where an array starting with a nonzero index is way more useful, or even, something simply cannot be done with an array starting at 0?

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  • PHP/MySQL Interview - How would you have answered?

    - by martincarlin87
    I was asked this interview question so thought I would post it here to see how other users would answer: Please write some code which connects to a MySQL database (any host/user/pass), retrieves the current date & time from the database, compares it to the current date & time on the local server (i.e. where the application is running), and reports on the difference. The reporting aspect should be a simple HTML page, so that in theory this script can be put on a web server, set to point to a particular database server, and it would tell us whether the two servers’ times are in sync (or close to being in sync). This is what I put: // Connect to database server $dbhost = 'localhost'; $dbuser = 'xxx'; $dbpass = 'xxx'; $dbname = 'xxx'; $conn = mysql_connect($dbhost, $dbuser, $dbpass) or die (mysql_error()); // Select database mysql_select_db($dbname) or die(mysql_error()); // Retrieve the current time from the database server $sql = 'SELECT NOW() AS db_server_time'; // Execute the query $result = mysql_query($sql) or die(mysql_error()); // Since query has now completed, get the time of the web server $php_server_time = date("Y-m-d h:m:s"); // Store query results in an array $row = mysql_fetch_array($result); // Retrieve time result from the array $db_server_time = $row['db_server_time']; echo $db_server_time . '<br />'; echo $php_server_time; if ($php_server_time != $db_server_time) { // Server times are not identical echo '<p>Database server and web server are not in sync!</p>'; // Convert the time stamps into seconds since 01/01/1970 $php_seconds = strtotime($php_server_time); $sql_seconds = strtotime($db_server_time); // Subtract smaller number from biggest number to avoid getting a negative result if ($php_seconds > $sql_seconds) { $time_difference = $php_seconds - $sql_seconds; } else { $time_difference = $sql_seconds - $php_seconds; } // convert the time difference in seconds to a formatted string displaying hours, minutes and seconds $nice_time_difference = gmdate("H:i:s", $time_difference); echo '<p>Time difference between the servers is ' . $nice_time_difference; } else { // Timestamps are exactly the same echo '<p>Database server and web server are in sync with each other!</p>'; } Yes, I know that I have used the deprecated mysql_* functions but that aside, how would you have answered, i.e. what changes would you make and why? Are there any factors I have omitted which I should take into consideration? The interesting thing is that my results always seem to be an exact number of minutes apart when executed on my hosting account: 2012-12-06 11:47:07 2012-12-06 11:12:07

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  • Making sense of S.M.A.R.T

    - by James
    First of all, I think everyone knows that hard drives fail a lot more than the manufacturers would like to admit. Google did a study that indicates that certain raw data attributes that the S.M.A.R.T status of hard drives reports can have a strong correlation with the future failure of the drive. We find, for example, that after their first scan error, drives are 39 times more likely to fail within 60 days than drives with no such errors. First errors in re- allocations, offline reallocations, and probational counts are also strongly correlated to higher failure probabil- ities. Despite those strong correlations, we find that failure prediction models based on SMART parameters alone are likely to be severely limited in their prediction accuracy, given that a large fraction of our failed drives have shown no SMART error signals whatsoever. Seagate seems like it is trying to obscure this information about their drives by claiming that only their software can accurately determine the accurate status of their drive and by the way their software will not tell you the raw data values for the S.M.A.R.T attributes. Western digital has made no such claim to my knowledge but their status reporting tool does not appear to report raw data values either. I've been using HDtune and smartctl from smartmontools in order to gather the raw data values for each attribute. I've found that indeed... I am comparing apples to oranges when it comes to certain attributes. I've found for example that most Seagate drives will report that they have many millions of read errors while western digital 99% of the time shows 0 for read errors. I've also found that Seagate will report many millions of seek errors while Western Digital always seems to report 0. Now for my question. How do I normalize this data? Is Seagate producing millions of errors while Western digital is producing none? Wikipedia's article on S.M.A.R.T status says that manufacturers have different ways of reporting this data. Here is my hypothesis: I think I found a way to normalize (is that the right term?) the data. Seagate drives have an additional attribute that Western Digital drives do not have (Hardware ECC Recovered). When you subtract the Read error count from the ECC Recovered count, you'll probably end up with 0. This seems to be equivalent to Western Digitals reported "Read Error" count. This means that Western Digital only reports read errors that it cannot correct while Seagate counts up all read errors and tells you how many of those it was able to fix. I had a Seagate drive where the ECC Recovered count was less than the Read error count and I noticed that many of my files were becoming corrupt. This is how I came up with my hypothesis. The millions of seek errors that Seagate produces are still a mystery to me. Please confirm or correct my hypothesis if you have additional information. Here is the smart status of my western digital drive just so you can see what I'm talking about: james@ubuntu:~$ sudo smartctl -a /dev/sda smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF INFORMATION SECTION === Device Model: WDC WD1001FALS-00E3A0 Serial Number: WD-WCATR0258512 Firmware Version: 05.01D05 User Capacity: 1,000,204,886,016 bytes Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Thu Jun 10 19:52:28 2010 PDT SMART support is: Available - device has SMART capability. SMART support is: Enabled === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 179 175 021 Pre-fail Always - 4033 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 270 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 098 098 000 Old_age Always - 1468 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 262 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 46 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 223 194 Temperature_Celsius 0x0022 105 102 000 Old_age Always - 42 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0

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  • The code works but when using printf it gives me a weird answer. Help please [closed]

    - by user71458
    //Programmer-William Chen //Seventh Period Computer Science II //Problem Statement - First get the elapsed times and the program will find the //split times for the user to see. // //Algorithm- First the programmer makes the prototype and calls them in the //main function. The programmer then asks the user to input lap time data. //Secondly, you convert the splits into seconds and subtract them so you can //find the splits. Then the average is all the lap time's in seconds. Finally, //the programmer printf all the results for the user to see. #include <iostream> #include <stdlib.h> #include <math.h> #include <conio.h> #include <stdio.h> using namespace std; void thisgetsElapsedTimes( int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5); //this is prototype void thisconvertstoseconds ( int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5, int &split1, int &split2, int &split3, int &split4, int &split5);//this too void thisfindsSplits(int &m1, int &m2, int &m3, int &m4, int &m5, int &split1, int &split2, int &split3, int &split4, int &split5, int &split6, int &split7, int &split8, int &split9, int &split10);// this is part of prototype void thisisthesecondconversation (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S,int &split2S, int &split3S, int &split4S, int &split5S, int &split1, int &split2, int &split3, int &split4, int &split5);//this gets a value void thisfindstheaverage(double &average, int &split1, int &split2, int &split3, int &split4, int &split5);//and this void thisprintsstuff( int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S, int &split2S, int &split3S, int &split4S, int &split5S, double &average); //this prints int main(int argc, char *argv[]) { int m1, m2, m3, m4, m5, s1, s2, s3, s4, s5, split1, split2, split3, split4, split5, split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S; int split6, split7, split8, split9, split10; double average; char thistakescolon; thisgetsElapsedTimes ( m1, m2, m3, m4, m5, s1, s2, s3, s4, s5); thisconvertstoseconds ( m1, m2, m3, m4, m5, s1, s2, s3, s4, s5, split1, split2, split3, split4, split5); thisfindsSplits ( m1, m2, m3, m4, m5, split1, split2, split3, split4, split5, split6, split7, split8, split9, split10); thisisthesecondconversation ( split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S, split1, split2, split3, split4, split5); thisfindstheaverage ( average, split1, split2, split3, split4, split5); thisprintsstuff ( split1M, split2M, split3M, split4M, split5M, split1S, split2S, split3S, split4S, split5S, average); // these are calling statements and they call from the main function to the other functions. system("PAUSE"); return 0; } void thisgetsElapsedTimes(int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5) { char thistakescolon; cout << "Enter the elapsed time:" << endl; cout << " Kilometer 1 "; cin m1 thistakescolon s1; cout << " Kilometer 2 "; cin m2 thistakescolon s2; cout << " Kilometer 3 " ; cin m3 thistakescolon s3; cout << " Kilometer 4 "; cin m4 thistakescolon s4; cout << " Kilometer 5 "; cin m5 thistakescolon s5; // this gets the data required to get the results needed for the user to see // . } void thisconvertstoseconds (int &m1, int &m2, int &m3, int &m4, int &m5, int &s1, int &s2, int &s3, int &s4, int &s5, int &split1, int &split2, int &split3, int &split4, int &split5) { split1 = (m1 * 60) + s1;//this converts for minutes to seconds for m1 split2 = (m2 * 60) + s2;//this converts for minutes to seconds for m2 split3 = (m3 * 60) + s3;//this converts for minutes to seconds for m3 split4 = (m4 * 60) + s4;//this converts for minutes to seconds for m4 split5 = (m5 * 60) + s5;//this converts for minutes to seconds for m5 } void thisfindsSplits (int &m1, int &m2, int &m3, int &m4, int &m5,int &split1, int &split2, int &split3, int &split4, int &split5, int &split6, int &split7, int &split8, int &split9, int &split10)//this is function heading { split6 = split1; //this is split for the first lap. split7 = split2 - split1;//this is split for the second lap. split8 = split3 - split2;//this is split for the third lap. split9 = split4 - split3;//this is split for the fourth lap. split10 = split5 - split4;//this is split for the fifth lap. } void thisfindstheaverage(double &average, int &split1, int &split2, int &split3, int &split4, int &split5) { average = (split1 + split2 + split3 + split4 + split5)/5; // this finds the average from all the splits in seconds } void thisisthesecondconversation (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S,int &split2S, int &split3S, int &split4S, int &split5S, int &split1, int &split2, int &split3, int &split4, int &split5) { split1M = split1 * 60; //this finds the split times split1S = split1M - split1 * 60; //then this finds split2M = split2 * 60; //and all of this split2S = split2M - split2 * 60; //does basically split3M = split3 * 60; //the same thing split3S = split3M - split3 * 60; //all of it split4M = split4 * 60; //it's also a split4S = split4M - split4 * 60; //function split5M = split5 * 60; //and it finds the splits split5S = split5M - split5 * 60; //for each lap. } void thisprintsstuff (int &split1M, int &split2M, int &split3M, int &split4M, int &split5M, int &split1S, int &split2S, int &split3S, int &split4S, int &split5S, double &average)// this is function heading { printf("\n kilometer 1 %d" , ":02%d",'split1M','split1S'); printf("\n kilometer 2 %d" , ":02%d",'split2M','split2S'); printf("\n kilometer 3 %d" , ":02%d",'split3M','split3S'); printf("\n kilometer 4 %d" , ":02%d",'split4M','split4S'); printf("\n kilometer 5 %d" , ":02%d",'split5M','split5S'); printf("\n your average pace is ",'average',"per kilometer \n", "William Chen\n"); // this printf so the programmer // can allow the user to see // the results from the data gathered. }

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  • Struct Method for Loops Problem

    - by Annalyne
    I have tried numerous times how to make a do-while loop using the float constructor for my code but it seems it does not work properly as I wanted. For summary, I am making a TBRPG in C++ and I encountered few problems. But before that, let me post my code. #include <iostream> #include <string> #include <ctime> #include <cstdlib> using namespace std; int char_level = 1; //the starting level of the character. string town; //town string town_name; //the name of the town the character is in. string charname; //holds the character's name upon the start of the game int gems = 0; //holds the value of the games the character has. const int MAX_ITEMS = 15; //max items the character can carry string inventory [MAX_ITEMS]; //the inventory of the character in game int itemnum = 0; //number of items that the character has. bool GameOver = false; //boolean intended for the game over scr. string monsterTroop [] = {"Slime", "Zombie", "Imp", "Sahaguin, Hounds, Vampire"}; //monster name float monsterTroopHealth [] = {5.0f, 10.0f, 15.0f, 20.0f, 25.0f}; // the health of the monsters int monLifeBox; //life carrier of the game's enemy troops int enemNumber; //enemy number //inventory[itemnum++] = "Sword"; class RPG_Game_Enemy { public: void enemyAppear () { srand(time(0)); enemNumber = 1+(rand()%3); if (enemNumber == 1) cout << monsterTroop[1]; //monster troop 1 else if (enemNumber == 2) cout << monsterTroop[2]; //monster troop 2 else if (enemNumber == 3) cout << monsterTroop[3]; //monster troop 3 else if (enemNumber == 4) cout << monsterTroop[4]; //monster troop 4 } void enemDefeat () { cout << "The foe has been defeated. You are victorious." << endl; } void enemyDies() { //if the enemy dies: //collapse declaration cout << "The foe vanished and you are victorious!" << endl; } }; class RPG_Scene_Battle { public: RPG_Scene_Battle(float ini_health) : health (ini_health){}; float getHealth() { return health; } void setHealth(float rpg_val){ health = rpg_val;}; private: float health; }; //---------------------------------------------------------------// // Conduct Damage for the Scene Battle's Damage //---------------------------------------------------------------// float conductDamage(RPG_Scene_Battle rpg_tr, float damage) { rpg_tr.setHealth(rpg_tr.getHealth() - damage); return rpg_tr.getHealth(); }; // ------------------------------------------------------------- // void RPG_Scene_DisplayItem () { cout << "Items: \n"; for (int i=0; i < itemnum; ++i) cout << inventory[i] <<endl; }; In this code I have so far, the problem I have is the battle scene. For example, the player battles a Ghost with 10 HP, when I use a do while loop to subtract the HP of the character and the enemy, it only deducts once in the do while. Some people said I should use a struct, but I have no idea how to make it. Is there a way someone can display a code how to implement it on my game? Edit: I made the do-while by far like this: do RPG_Scene_Battle (player, 20.0f); RPG_Scene_Battle (enemy, 10.0f); cout << "Battle starts!" <<endl; cout << "You used a blade skill and deducted 2 hit points to the enemy!" conductDamage (enemy, 2.0f); while (enemy!=0) also, I made something like this: #include <iostream> using namespace std; int gems = 0; class Entity { public: Entity(float startingHealth) : health(startingHealth){}; // initialize health float getHealth(){return health;} void setHealth(float value){ health = value;}; private: float health; }; float subtractHealthFrom(Entity& ent, float damage) { ent.setHealth(ent.getHealth() - damage); return ent.getHealth(); }; int main () { Entity character(10.0f); Entity enemy(10.0f); cout << "Hero Life: "; cout << subtractHealthFrom(character, 2.0f) <<endl; cout << "Monster Life: "; cout << subtractHealthFrom(enemy, 2.0f) <<endl; cout << "Hero Life: "; cout << subtractHealthFrom(character, 2.0f) <<endl; cout << "Monster Life: "; cout << subtractHealthFrom(enemy, 2.0f) <<endl; }; Struct method, they say, should solve this problem. How can I continously deduct hp from the enemy? Whenever I deduct something, it would return to its original value -_-

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  • "'0.offsetWidth' is null or not an object" - Coda Slider - Javascript Error Question

    - by bgadoci
    I implemented the Coda Slider tutorial successfully that is located here: http://jqueryfordesigners.com/coda-slider-effect/ The slider works great but I am getting a javascript error that I am not sure how to fix. The error says: '0.offsetWidth' is null or not an object coda-slider.js, line 19 character 3 Not sure how to fix it. Anyone have any ideas? Here is my js and css (don't think I need to upload the HTML but let me know if that helps). JS (coda-slider.js) // when the DOM is ready... $(document).ready(function () { var $panels = $('#slider .scrollContainer > div'); var $container = $('#slider .scrollContainer'); // if false, we'll float all the panels left and fix the width // of the container var horizontal = true; // float the panels left if we're going horizontal if (horizontal) { $panels.css({ 'float' : 'left', 'position' : 'relative' // IE fix to ensure overflow is hidden }); // calculate a new width for the container (so it holds all panels) $container.css('width', $panels[0].offsetWidth * $panels.length); <------line 19 } // collect the scroll object, at the same time apply the hidden overflow // to remove the default scrollbars that will appear var $scroll = $('#slider .scroll').css('overflow', 'hidden'); // apply our left + right buttons $scroll .before('<img class="scrollButtons left" src="/images/layout/navigation/scroll_left.png" />') .after('<img class="scrollButtons right" src="/images/layout/navigation/scroll_right.png" />'); // handle nav selection function selectNav() { $(this) .parents('ul:first') .find('a') .removeClass('selected') .end() .end() .addClass('selected'); } $('#slider .navigation').find('a').click(selectNav); // go find the navigation link that has this target and select the nav function trigger(data) { var el = $('#slider .navigation').find('a[href$="' + data.id + '"]').get(0); selectNav.call(el); } if (window.location.hash) { trigger({ id : window.location.hash.substr(1) }); } else { $('ul.navigation a:first').click(); } // offset is used to move to *exactly* the right place, since I'm using // padding on my example, I need to subtract the amount of padding to // the offset. Try removing this to get a good idea of the effect var offset = parseInt((horizontal ? $container.css('paddingTop') : $container.css('paddingLeft')) || 0) * -1; var scrollOptions = { target: $scroll, // the element that has the overflow // can be a selector which will be relative to the target items: $panels, navigation: '.navigation a', // selectors are NOT relative to document, i.e. make sure they're unique prev: 'img.left', next: 'img.right', // allow the scroll effect to run both directions axis: 'xy', onAfter: trigger, // our final callback offset: offset, // duration of the sliding effect duration: 500, // easing - can be used with the easing plugin: // http://gsgd.co.uk/sandbox/jquery/easing/ easing: 'swing' }; // apply serialScroll to the slider - we chose this plugin because it // supports// the indexed next and previous scroll along with hooking // in to our navigation. $('#slider').serialScroll(scrollOptions); // now apply localScroll to hook any other arbitrary links to trigger // the effect $.localScroll(scrollOptions); // finally, if the URL has a hash, move the slider in to position, // setting the duration to 1 because I don't want it to scroll in the // very first page load. We don't always need this, but it ensures // the positioning is absolutely spot on when the pages loads. scrollOptions.duration = 1; $.localScroll.hash(scrollOptions); }); CSS #slider { margin-left: 35px; position: relative; width: 875px; } .scroll { position: relative; width: 875px; height: 268px; overflow: auto; /* fix for IE to respect overflow */ background: #FFFFFF scroll 0; } .scrollContainer div.panel { position: relative; height: 210px; width: 875px; /* change to 560px if not using JS to remove rh.scroll */ } .scrollButtons { position: absolute; top: 115px; cursor: pointer; } .scrollButtons.left { left: -20px; } .scrollButtons.right { right: -20px; }

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  • Small performance test on a web service

    - by vtortola
    Hi, I'm trying to develop a small application that test how many requests per second can my service support but I think I'm doing something wrong. The service is in an early development stage, but I'd like to have this test handy in order to check in time to time I'm not doing something that decrease the performance. The problem is that I cannot get the web server or the database server go to the 100% of CPU. I'm using three different computers, in one is the web server (WinSrv Standard 2008 x64 IIS7), in other the database (Win 2K - SQL Server 2005) and the last is my computer (Win7 x64 ultimate), where I'll run the test. The computers are connected through a 100 ethernet switch. The request POST is 9 bytes and the response will be 842 bytes. The test launches several threads, and each thread has a "while" loop, in each loop it creates a WebRequest object, performs a call, increment a common counter and waits between 1 and 5 millisencods, then it do it again: static Int32 counter = 0; static void Main(string[] args) { ServicePointManager.DefaultConnectionLimit = 250; Console.WriteLine("Ready. Press any key..."); Console.ReadKey(); Console.WriteLine("Running..."); String localhost = "localhost"; String linuxmono = "192.168.1.74"; String server= "192.168.1.5:8080"; DateTime start = DateTime.Now; Random r = new Random(DateTime.Now.Millisecond); for (int i = 0; i < 50; i++) { new Thread(new ParameterizedThreadStart(Test)).Start(server); Thread.Sleep(r.Next(1, 3)); } Thread.Sleep(2000); while (true) { Console.WriteLine("Request per second :" + counter/DateTime.Now.Subtract(start).TotalSeconds ); Thread.Sleep(3000); } } public static void Test(Object ip) { Guid guid = Guid.NewGuid(); Random r = new Random(DateTime.Now.Millisecond); while (true) { String test = "<lalala/>"; WebRequest req = WebRequest.Create("http://" + (String)ip + "/WebApp/"+guid.ToString()+"/Data/Tables=whatever"); req.Method = "POST"; req.ContentType = "application/xml"; req.Credentials = new NetworkCredential("aaa", "aaa","domain"); Byte[] array = Encoding.UTF8.GetBytes(test); req.ContentLength = array.Length; using (Stream reqStream = req.GetRequestStream()) { reqStream.Write(array, 0, array.Length); reqStream.Close(); } using (Stream responseStream = req.GetResponse().GetResponseStream()) { String response = new StreamReader(responseStream).ReadToEnd(); if (response.Length != 842) Console.Write(" EEEE "); } Interlocked.Increment(ref counter); Thread.Sleep(r.Next(1,5)); } } If I run the test neither of the computers do an excesive CPU usage. Let's say I get a X requests per second, if I run the console application two times at the same moment, I get X/2 request per second in each one... but still the web server is on 30% of CPU, the database server on 25%... I've tried to remove the thread.sleep in the loop, but it doesn't make a big difference. I'd like to put the machines to the maximun, to check how may requests per second they can provide. I guessed that I could do it in this way... but apparently I'm missing something here... What is the problem? Kind regards.

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  • How does a template class inherit another template class?

    - by hkBattousai
    I have a "SquareMatrix" template class which inherits "Matrix" template class, like below: SquareMatrix.h: #ifndef SQUAREMATRIX_H #define SQUAREMATRIX_H #include "Matrix.h" template <class T> class SquareMatrix : public Matrix<T> { public: T GetDeterminant(); }; template <class T> // line 49 T SquareMatrix<T>::GetDeterminant() { T t = 0; // Error: Identifier "T" is undefined // line 52 return t; // Error: Expected a declaration // line 53 } // Error: Expected a declaration // line 54 #endif I commented out all other lines, the files contents are exactly as above. I receive these error messages: LINE 49: IntelliSense: expected a declaration LINE 52: IntelliSense: expected a declaration LINE 53: IntelliSense: expected a declaration LINE 54: error C2039: 'GetDeterminant' : is not a member of 'SquareMatrix' LINE 54: IntelliSense: expected a declaration So, what is the correct way of inheriting a template class? And what is wrong with this code? The "Matrix" class: template <class T> class Matrix { public: Matrix(uint64_t unNumRows = 0, uint64_t unNumCols = 0); void GetDimensions(uint64_t & unNumRows, uint64_t & unNumCols) const; std::pair<uint64_t, uint64_t> GetDimensions() const; void SetDimensions(uint64_t unNumRows, uint64_t unNumCols); void SetDimensions(std::pair<uint64_t, uint64_t> Dimensions); uint64_t GetRowSize(); uint64_t GetColSize(); void SetElement(T dbElement, uint64_t unRow, uint64_t unCol); T & GetElement(uint64_t unRow, uint64_t unCol); //Matrix operator=(const Matrix & rhs); // Compiler generate this automatically Matrix operator+(const Matrix & rhs) const; Matrix operator-(const Matrix & rhs) const; Matrix operator*(const Matrix & rhs) const; Matrix & operator+=(const Matrix & rhs); Matrix & operator-=(const Matrix & rhs); Matrix & operator*=(const Matrix & rhs); T& operator()(uint64_t unRow, uint64_t unCol); const T& operator()(uint64_t unRow, uint64_t unCol) const; static Matrix Transpose (const Matrix & matrix); static Matrix Multiply (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Add (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Subtract (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Negate (const Matrix & matrix); // TO DO: static bool IsNull(const Matrix & matrix); static bool IsSquare(const Matrix & matrix); static bool IsFullRowRank(const Matrix & matrix); static bool IsFullColRank(const Matrix & matrix); // TO DO: static uint64_t GetRowRank(const Matrix & matrix); static uint64_t GetColRank(const Matrix & matrix); protected: std::vector<T> TheMatrix; uint64_t m_unRowSize; uint64_t m_unColSize; bool DoesElementExist(uint64_t unRow, uint64_t unCol); };

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  • Detecting Acceleration in a car (iPhone Accelerometer)

    - by TheGazzardian
    Hello, I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is that this app is designed to be used during general city driving, not on a drag strip. This leads us to one big concern that Dynolicious was luckily able to avoid: hills. Yes, hills. There are two important stages to this: calibration, and actual driving. Our initial run was simple and suffered the consequences. During the calibration stage, I took the average force on the phone, and during running, I just subtracted the average force from the current force to get the current acceleration this frame. The problem with this is that the typical car receives much more force than just the forward force - everything from turning to potholes was causing the values to go out of sync with what was really happening. The next run was to add the condition that the iPhone must be oriented in such a way that the screen was facing toward the back of the car. Using this method, I attempted to follow only force on the z-axis, but this obviously lead to problems unless the iPhone was oriented directly upright, because of gravity. Some trigonometry later, and I had managed to work gravity out of the equation, so that the car was actually being read very, very well by the iPhone. Until I hit a slope. As soon as the angle of the car changed, suddenly I was receiving accelerations and decelerations that didn't make sense, and we were once again going out of sync. Talking with someone a lot smarter than me at math lead to a solution that I have been trying to implement for longer than I would like to admit. It's steps are as follows: 1) During calibration, measure gravity as a vector instead of a size. Store that vector. 2) When the car initially moves forward, take the vector of motion and subtract gravity. Use this as the forward momentum. (Ignore, for now, the user cases where this will be difficult and let's concentrate on the math :) 3) From the forward vector and the gravity vector, construct a plane. 4) Whenever a force is received, project it onto said plane to get rid of sideways force/etc. 5) Then, use that force, the known magnitude of gravity, and the known direction of forward motion to essentially solve a triangle to get the forward vector. The problem that is causing the most difficulty in this new system is not step 5, which I have gotten to the point where all the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity, and from there, averaging them and subtracting gravity. (I am doing some error checking to make sure that I am not using a force just because the iPhone accelerometer was off by a bit, which happens more frequently than I would like). But if I plot these vectors that I am using, they actually vary by an angle of about 20-30 degrees, which can lead to some strong inaccuracies. The end result is that the app is even more inaccurate now than before. So basically - all you math and iPhone brains out there - any glaring errors? Any potentially better solutions? Any experience that could be useful at all? Award: offering a bounty of $250 to the first answer that leads to a solution.

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  • When to draw/layout child controls in UserControl

    - by Ted Elliott
    I have a list-type UserControl (like a ListBox). The items inside the control are another complex UserControl containing a few other controls (ComboBox, TextBox, etc). I'm wondering what the preferred or best method would be to override to draw/layout the child controls. I basically want to trigger this method any time the list changes. I originally had a RedrawItems method that I just called whenever I needed to redraw which added or removed Controls from the Controls collection. But it was getting triggered too early in the lifecycle of the code from some of the designer code. Now I've switched to overriding OnLayout and doing my stuff there. I call PerformLayout when I want to trigger a redraw, such as when the DataSource property changes or when it fires a changed event. Is OnLayout the best place for this? Here is the code: [ComplexBindingProperties("DataSource")] public partial class CustomList : UserControl { private object _dataSource; private CustomListItem _newRow; public CustomList() { InitializeComponent(); } protected override void OnCreateControl() { base.OnCreateControl(); _newRow = new CustomListItem(); Controls.Add(_newRow); } public object DataSource { get { return _dataSource; } set { bool register = _dataSource != value; if (_dataSource != null && _dataSource != value) { UnregisterDataSource(_dataSource); } _dataSource = value; if (_dataSource != null) RegisterDataSource(_dataSource); PerformLayout(); } } public CustomListItem ItemTemplate { get { return _newRow; } } protected override void OnLayout(LayoutEventArgs e) { base.OnLayout(e); int ctrlCount = this.Controls.AsEnumerable().OfType<CustomListItem>().Count(); ctrlCount--; // subtract 1 for the add row var ds = this.DataSource as System.Collections.IList; int itemCount = ds == null? 0 : ds.Count; int maxCount = Math.Max(ctrlCount,itemCount); if (maxCount == 0) return; this.SuspendLayout(); // temporarily remove the template Controls.RemoveAt(Controls.Count-1); for (int i = 0; i < maxCount; i++) { CustomListItem item; if (i >= itemCount) { Controls.RemoveAt(i); } else { if (i >= ctrlCount) { item = ItemTemplate.Copy(); this.Controls.Add(item); item.Location = new Point(0, item.Height * i); item.TabIndex = i + 1; item.ViewMode = true; } else { item = (CustomListItem) Controls[i]; } item.Data = ds[i]; } } this.Controls.Add(ItemTemplate); ItemTemplate.Location = new Point(0, ItemTemplate.Height * maxCount); ItemTemplate.TabIndex = maxCount + 1; this.ResumeLayout(true); } private void RegisterDataSource(object dataSource) { IBindingList ds = dataSource as IBindingList; if (ds != null) { ds.ListChanged += new ListChangedEventHandler(DataSource_ListChanged); } } void DataSource_ListChanged(object sender, ListChangedEventArgs e) { switch (e.ListChangedType) { case ListChangedType.ItemAdded: PerformLayout(); break; case ListChangedType.ItemChanged: break; case ListChangedType.ItemDeleted: PerformLayout(); break; case ListChangedType.ItemMoved: PerformLayout(); break; case ListChangedType.Reset: PerformLayout(); break; default: break; } } private void UnregisterDataSource(object dataSource) { IBindingList ds = dataSource as IBindingList; if (ds != null) { ds.ListChanged -= new ListChangedEventHandler(DataSource_ListChanged); } } }

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  • Performance issues with repeatable loops as control part

    - by djerry
    Hey guys, In my application, i need to show made calls to the user. The user can arrange some filters, according to what they want to see. The problem is that i find it quite hard to filter the calls without losing performance. This is what i am using now : private void ProcessFilterChoice() { _filteredCalls = ServiceConnector.ServiceConnector.SingletonServiceConnector.Proxy.GetAllCalls().ToList(); if (cboOutgoingIncoming.SelectedIndex > -1) GetFilterPartOutgoingIncoming(); if (cboInternExtern.SelectedIndex > -1) GetFilterPartInternExtern(); if (cboDateFilter.SelectedIndex > -1) GetFilteredCallsByDate(); wbPdf.Source = null; btnPrint.Content = "Pdf preview"; } private void GetFilterPartOutgoingIncoming() { if (cboOutgoingIncoming.SelectedItem.ToString().Equals("Outgoing")) for (int i = _filteredCalls.Count - 1; i > -1; i--) { if (_filteredCalls[i].Caller.E164.Length > 4 || _filteredCalls[i].Caller.E164.Equals("0")) _filteredCalls.RemoveAt(i); } else if (cboOutgoingIncoming.SelectedItem.ToString().Equals("Incoming")) for (int i = _filteredCalls.Count - 1; i > -1; i--) { if (_filteredCalls[i].Called.E164.Length > 4 || _filteredCalls[i].Called.E164.Equals("0")) _filteredCalls.RemoveAt(i); } } private void GetFilterPartInternExtern() { if (cboInternExtern.SelectedItem.ToString().Equals("Intern")) for (int i = _filteredCalls.Count - 1; i > -1; i--) { if (_filteredCalls[i].Called.E164.Length > 4 || _filteredCalls[i].Caller.E164.Length > 4 || _filteredCalls[i].Caller.E164.Equals("0")) _filteredCalls.RemoveAt(i); } else if (cboInternExtern.SelectedItem.ToString().Equals("Extern")) for (int i = _filteredCalls.Count - 1; i > -1; i--) { if ((_filteredCalls[i].Called.E164.Length < 5 && _filteredCalls[i].Caller.E164.Length < 5) || _filteredCalls[i].Called.E164.Equals("0")) _filteredCalls.RemoveAt(i); } } private void GetFilteredCallsByDate() { DateTime period = DateTime.Now; switch (cboDateFilter.SelectedItem.ToString()) { case "Today": period = DateTime.Today; break; case "Last week": period = DateTime.Today.Subtract(new TimeSpan(7, 0, 0, 0)); break; case "Last month": period = DateTime.Today.AddMonths(-1); break; case "Last year": period = DateTime.Today.AddYears(-1); break; default: return; } for (int i = _filteredCalls.Count - 1; i > -1; i--) { if (_filteredCalls[i].Start < period) _filteredCalls.RemoveAt(i); } } _filtered calls is a list of "calls". Calls is a class that looks like this : [DataContract] public class Call { private User caller, called; private DateTime start, end; private string conferenceId; private int id; private bool isNew = false; [DataMember] public bool IsNew { get { return isNew; } set { isNew = value; } } [DataMember] public int Id { get { return id; } set { id = value; } } [DataMember] public string ConferenceId { get { return conferenceId; } set { conferenceId = value; } } [DataMember] public DateTime End { get { return end; } set { end = value; } } [DataMember] public DateTime Start { get { return start; } set { start = value; } } [DataMember] public User Called { get { return called; } set { called = value; } } [DataMember] public User Caller { get { return caller; } set { caller = value; } } Can anyone direct me to a better solution or make some suggestions.

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  • Overloading '-' for array subtraction

    - by Chris Wilson
    I am attempting to subtract two int arrays, stored as class members, using an overloaded - operator, but I'm getting some peculiar output when I run tests. The overload definition is Number& Number :: operator-(const Number& NumberObject) { for (int count = 0; count < NumberSize; count ++) { Value[count] -= NumberObject.Value[count]; } return *this; } Whenever I run tests on this, NumberObject.Value[count] always seems to be returning a zero value. Can anyone see where I'm going wrong with this? The line in main() where this subtraction is being carried out is cout << "The difference is: " << ArrayOfNumbers[0] - ArrayOfNumbers[1] << endl; ArrayOfNumbers contains two Number objects. The class declaration is #include <iostream> using namespace std; class Number { private: int Value[50]; int NumberSize; public: Number(); // Default constructor Number(const Number&); // Copy constructor Number(int, int); // Non-default constructor void SetMemberValues(int, int); // Manually set member values int GetNumberSize() const; // Return NumberSize member int GetValue() const; // Return Value[] member Number& operator-=(const Number&); }; inline Number operator-(Number Lhs, const Number& Rhs); ostream& operator<<(ostream&, const Number&); The full class definition is as follows: #include <iostream> #include "../headers/number.h" using namespace std; // Default constructor Number :: Number() {} // Copy constructor Number :: Number(const Number& NumberObject) { int Temp[NumberSize]; NumberSize = NumberObject.GetNumberSize(); for (int count = 0; count < NumberObject.GetNumberSize(); count ++) { Temp[count] = Value[count] - NumberObject.GetValue(); } } // Manually set member values void Number :: SetMemberValues(int NewNumberValue, int NewNumberSize) { NumberSize = NewNumberSize; for (int count = NewNumberSize - 1; count >= 0; count --) { Value[count] = NewNumberValue % 10; NewNumberValue = NewNumberValue / 10; } } // Non-default constructor Number :: Number(int NumberValue, int NewNumberSize) { NumberSize = NewNumberSize; for (int count = NewNumberSize - 1; count >= 0; count --) { Value[count] = NumberValue % 10; NumberValue = NumberValue / 10; } } // Return the NumberSize member int Number :: GetNumberSize() const { return NumberSize; } // Return the Value[] member int Number :: GetValue() const { int ResultSoFar; for (int count2 = 0; count2 < NumberSize; count2 ++) { ResultSoFar = ResultSoFar * 10 + Value[count2]; } return ResultSoFar; } Number& operator-=(const Number& Rhs) { for (int count = 0; count < NumberSize; count ++) { Value[count] -= Rhs.Value[count]; } return *this; } inline Number operator-(Number Lhs, const Number& Rhs) { Lhs -= Rhs; return Lhs; } // Overloaded output operator ostream& operator<<(ostream& OutputStream, const Number& NumberObject) { OutputStream << NumberObject.GetValue(); return OutputStream; }

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  • Add User to Database not working

    - by user1850189
    I'm really new to ASP.net and I am currently trying to create a registration page on a site. I was successful in adding a user to the database but I decided to add another feature into the code to check what userID's were available. For example, if a user deleted their account their userID would become available for use again. I'm trying to find the min value and the max value and add or subtract 1 depending on whether it is min or max. I can run the code I have written for this with no errors but the user is not added to the database. Can anyone help me figure out what I'm missing from my code to do this? EDIT Code adds a user to database but it adds the new user at -1 instead. I don't seem to be able to see where the issue is. If (aDataReader2.Read() = False) Then aConnection1 = New OleDbConnection(aConnectionString) aConnection1.Open() aQuery = "Insert Into UserDetails " aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')" aCommand = New OleDbCommand(aQuery, aConnection1) aCommand.ExecuteNonQuery() aConnection1.Close() ElseIf (min = 1) Then aConnection2 = New OleDbConnection(aConnectionString) aConnection2.Open() aCommand = New OleDbCommand(aQuery3, aConnection2) aDataReader2 = aCommand.ExecuteReader() userID = max + 1 aQuery = "Insert Into UserDetails " aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')" aCommand = New OleDbCommand(aQuery, aConnection2) aCommand.ExecuteNonQuery() aConnection2.Close() Else aConnection3 = New OleDbConnection(aConnectionString) aConnection3.Open() aCommand = New OleDbCommand(aQuery2, aConnection3) aDataReader2 = aCommand.ExecuteReader userID = min - 1 aQuery = "Insert Into UserDetails " aQuery = aQuery & "Values ('" & userID & "','" & userFName & "','" & userLName & "','" & userEmail & "','" & userUsername & "','" & userPassword & "')" aCommand = New OleDbCommand(aQuery, aConnection3) aCommand.ExecuteNonQuery() aConnection3.Close() lblResults.Text = "User Account successfully created" btnCreateUser.Enabled = False End If Here's the code I used to get the max and min values from the database. I'm getting a value of 0 for both of them - when min should be 1 and max should be 5 Dim minID As Integer Dim maxID As Integer aQuery2 = "Select Min(UserID) AS '" & [minID] & "' From UserDetails" aQuery3 = "Select Max(UserID) AS ' " & [maxID] & "' From UserDetails"

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  • Get the screen height in Android

    - by Dan Bray
    How can I get the available height of the screen in Android? I need to the height minus the status bar / menu bar or any other decorations that might be on screen and I need it to work for all devices. Also, I need to know this in the onCreate function. I know this question has been asked before but I have already tried their solutions and none of them work. Here are some of the things I have tried: I have tested this code on API 7 - 17. Unfortunately, on API 13 there is extra space at bottom both horizontally and vertically and on API 10, 8, and 7 there is not enough space at the bottom both horizontally and vertically. (I have not tested on obsolete API's): Display display = getWindowManager().getDefaultDisplay(); DisplayMetrics metrics = new DisplayMetrics(); display.getMetrics(metrics); screenWidth = metrics.widthPixels; screenHeight = metrics.heightPixels; TypedValue tv = new TypedValue(); if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { if (getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) screenHeight -= TypedValue.complexToDimensionPixelSize(tv.data,getResources().getDisplayMetrics()); } int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android"); if (resourceId > 0) screenHeight -= getResources().getDimensionPixelSize(resourceId); This does not take into account the status bar / menu bar: Display display = getWindowManager().getDefaultDisplay(); screenWidth = display.getWidth(); screenHeight = display.getHeight(); Neither does this: Point size = new Point(); getWindowManager().getDefaultDisplay().getSize(size); screenWidth = size.x; screenHeight = size.y; Nor this: Point size = new Point(); getWindowManager().getDefaultDisplay().getRealSize(size); screenWidth = size.x; screenHeight = size.y; This does not work: Display display = getWindowManager().getDefaultDisplay(); DisplayMetrics metrics = new DisplayMetrics(); display.getMetrics(metrics); // since SDK_INT = 1; screenWidth = metrics.widthPixels; screenHeight = metrics.heightPixels; try { // used when 17 > SDK_INT >= 14; includes window decorations (statusbar bar/menu bar) screenWidth = (Integer) Display.class.getMethod("getRawWidth").invoke(display); screenHeight = (Integer) Display.class.getMethod("getRawHeight").invoke(display); } catch (Exception ignored) { // Do nothing } try { // used when SDK_INT >= 17; includes window decorations (statusbar bar/menu bar) Point realSize = new Point(); Display.class.getMethod("getRealSize", Point.class).invoke(display, realSize); screenWidth = realSize.x; screenHeight = realSize.y; } catch (Exception ignored) { // Do nothing } I then used the following code to subtract the height of the status bar and menu bar from the screen height: int result = 0; int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android"); if (resourceId > 0) result = getResources().getDimensionPixelSize(resourceId); screenHeight -= result; result = 0; if (screenHeight >= screenWidth) resourceId = getResources().getIdentifier("navigation_bar_height", "dimen", "android"); else resourceId = getResources().getIdentifier("navigation_bar_height_landscape", "dimen", "android"); if (resourceId > 0) result = getResources().getDimensionPixelSize(resourceId); screenHeight -= result; On API 17 it correctly calculates the height of the status bar and menu bar in portrait but not in landscape. On API 10, it returns 0. I need it to work ideally on all devices or minimum API 7. Any help would be greatly appreciated.

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  • compareTo() method java is acting weird

    - by Ron Paul
    hi im having trouble getting this to work im getting an error here with my object comparison...how could I cast the inches to a string ( i never used compare to with anything other than strings) , or use comparison operators to compare the intigers, Object comparison = this.inches.compareTo(obj.inches); here is my code so far import java.io.*; import java.util.*; import java.lang.Integer; import java.lang.reflect.Array; public class Distance implements Comparable<Distance> { private static final String HashCodeUtil = null; private int feet; private int inches; private final int DEFAULT_FT = 1; private final int DEFAULT_IN = 1; public Distance(){ feet = DEFAULT_FT; inches = DEFAULT_IN; } public Distance(int ft, int in){ feet = ft; inches = in; } public void setFeet(int ft){ try { if(ft<0){ throw new CustomException("Distance is not negative"); } } catch(CustomException c){ System.err.println(c); feet =ft; } } public int getFeet(){ return feet; } public void setInches(int in){ try { if (in<0) throw new CustomException("Distance is not negative"); //inches = in; } catch(CustomException c) { System.err.println(c); inches = in; } } public int getInches(){ return inches; } public String toString (){ return "<" + feet + ":" + inches + ">"; } public Distance add(Distance m){ Distance n = new Distance(); n.inches = this.inches + m.inches; n.feet = this.feet + m.feet; while(n.inches>12){ n.inches = n.inches - 12; n.feet++; } return n; } public Distance subtract(Distance f){ Distance m = new Distance(); m.inches = this.inches - f.inches; m.feet = this.feet - f.feet; while(m.inches<0){ m.inches = m.inches - 12; feet--; } return m; } @Override public int compareTo(Distance obj) { // TODO Auto-generated method stub final int BEFORE = -1; final int EQUAL = 0; final int AFTER = 1; if (this == obj) return EQUAL; if(this.DEFAULT_IN < obj.DEFAULT_FT) return BEFORE; if(this.DEFAULT_IN > obj.DEFAULT_FT) return AFTER; Object comparison = this.inches.compareTo(obj.inches); if (this.inches == obj.inches) return compareTo(null); assert this.equals(obj) : "compareTo inconsistent with equals"; return EQUAL; } @Override public boolean equals( Object obj){ if (obj != null) return false; if (!(obj intanceof Distance)) return false; Distance that = (Distance)obj; ( this.feet == that.feet && this.inches == that.inches); return true; else return false; } @Override public int hashCode(int, int) { int result = HashCodeUtil.inches; result = HashCodeUtil.hash(result, inches ); result = HashCodeUtil.hash(result, feet); ruturn result; }

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  • database design help for game / user levels / progress

    - by sprugman
    Sorry this got long and all prose-y. I'm creating my first truly gamified web app and could use some help thinking about how to structure the data. The Set-up Users need to accomplish tasks in each of several categories before they can move up a level. I've got my Users, Tasks, and Categories tables, and a UserTasks table which joins the three. ("User 3 has added Task 42 in Category 8. Now they've completed it.") That's all fine and working wonderfully. The Challenge I'm not sure of the best way to track the progress in the individual categories toward each level. The "business" rules are: You have to achieve a certain number of points in each category to move up. If you get the number of points needed in Cat 8, but still have other work to do to complete the level, any new Cat 8 points count toward your overall score, but don't "roll over" into the next level. The number of Categories is small (five currently) and unlikely to change often, but by no means absolutely fixed. The number of points needed to level-up will vary per level, probably by a formula, or perhaps a lookup table. So the challenge is to track each user's progress toward the next level in each category. I've thought of a few potential approaches: Possible Solutions Add a column to the users table for each category and reset them all to zero each time a user levels-up. Have a separate UserProgress table with a row for each category for each user and the number of points they have. (Basically a Many-to-Many version of #1.) Add a userLevel column to the UserTasks table and use that to derive their progress with some kind of SUM statement. Their current level will be a simple int in the User table. Pros & Cons (1) seems like by far the most straightforward, but it's also the least flexible. Perhaps I could use a naming convention based on the category ids to help overcome some of that. (With code like "select cats; for each cat, get the value from Users.progress_{cat.id}.") It's also the one where I lose the most data -- I won't know which points counted toward leveling up. I don't have a need in mind for that, so maybe I don't care about that. (2) seems complicated: every time I add or subtract a user or a category, I have to maintain the other table. I foresee synchronization challenges. (3) Is somewhere in between -- cleaner than #2, but less intuitive than #1. In order to find out where a user is, I'd have mildly complex SQL like: SELECT categoryId, SUM(points) from UserTasks WHERE userId={user.id} & countsTowardLevel={user.level} groupBy categoryId Hmm... that doesn't seem so bad. I think I'm talking myself into #3 here, but would love any input, advice or other ideas.

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  • Silverlight for Windows Embedded tutorial (step 6)

    - by Valter Minute
    In this tutorial step we will develop a very simple clock application that may be used as a screensaver on our devices and will allow us to discover a new feature of Silverlight for Windows Embedded (transforms) and how to use an “old” feature of Windows CE (timers) inside a Silverlight for Windows Embedded application. Let’s start with some XAML, as usual: <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="640" Height="480" FontSize="18" x:Name="Clock">   <Canvas x:Name="LayoutRoot" Background="#FF000000"> <Grid Height="24" Width="150" Canvas.Left="320" Canvas.Top="234" x:Name="SecondsHand" Background="#FFFF0000"> <TextBlock Text="Seconds" TextWrapping="Wrap" Width="50" HorizontalAlignment="Right" VerticalAlignment="Center" x:Name="SecondsText" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> <Grid Height="24" x:Name="MinutesHand" Width="100" Background="#FF00FF00" Canvas.Left="320" Canvas.Top="234"> <TextBlock HorizontalAlignment="Right" x:Name="MinutesText" VerticalAlignment="Center" Width="50" Text="Minutes" TextWrapping="Wrap" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> <Grid Height="24" x:Name="HoursHand" Width="50" Background="#FF0000FF" Canvas.Left="320" Canvas.Top="234"> <TextBlock HorizontalAlignment="Right" x:Name="HoursText" VerticalAlignment="Center" Width="50" Text="Hours" TextWrapping="Wrap" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> </Canvas> </UserControl> This XAML file defines three grid panels, one for each hand of our clock (we are implementing an analog clock using one of the most advanced technologies of the digital world… how cool is that?). Inside each hand we put a TextBlock that will be used to display the current hour, minute, second inside the dial (you can’t do that on plain old analog clocks, but it looks nice). As usual we use XAML2CPP to generate the boring part of our code. We declare a class named “Clock” and derives from the TClock template that XAML2CPP has declared for us. class Clock : public TClock<Clock> { ... }; Our WinMain function is more or less the same we used in all the previous samples. It initializes the XAML runtime, create an instance of our class, initialize it and shows it as a dialog: int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { if (!XamlRuntimeInitialize()) return -1;   HRESULT retcode;   IXRApplicationPtr app; if (FAILED(retcode=GetXRApplicationInstance(&app))) return -1; Clock clock;   if (FAILED(clock.Init(hInstance,app))) return -1;     UINT exitcode;   if (FAILED(clock.GetVisualHost()->StartDialog(&exitcode))) return -1;   return exitcode; } Silverlight for Windows Embedded provides a lot of features to implement our UI, but it does not provide timers. How we can update our clock if we don’t have a timer feature? We just use plain old Windows timers, as we do in “regular” Windows CE applications! To use a timer in WinCE we should declare an id for it: #define IDT_CLOCKUPDATE 0x12341234 We also need an HWND that will be used to receive WM_TIMER messages. Our Silverlight for Windows Embedded page is “hosted” inside a GWES Window and we can retrieve its handle using the GetContainerHWND function of our VisualHost object. Let’s see how this is implemented inside our Clock class’ Init method: HRESULT Init(HINSTANCE hInstance,IXRApplication* app) { HRESULT retcode;   if (FAILED(retcode=TClock<Clock>::Init(hInstance,app))) return retcode;   // create the timer user to update the clock HWND clockhwnd;   if (FAILED(GetVisualHost()->GetContainerHWND(&clockhwnd))) return -1;   timer=SetTimer(clockhwnd,IDT_CLOCKUPDATE,1000,NULL); return 0; } We use SetTimer to create a new timer and GWES will send a WM_TIMER to our window every second, giving us a chance to update our clock. That sounds great… but how could we handle the WM_TIMER message if we didn’t implement a window procedure for our window? We have to move a step back and look how a visual host is created. This code is generated by XAML2CPP and is inside xaml2cppbase.h: virtual HRESULT CreateHost(HINSTANCE hInstance,IXRApplication* app) { HRESULT retcode; XRWindowCreateParams wp;   ZeroMemory(&wp, sizeof(XRWindowCreateParams)); InitWindowParms(&wp);   XRXamlSource xamlsrc;   SetXAMLSource(hInstance,&xamlsrc); if (FAILED(retcode=app->CreateHostFromXaml(&xamlsrc, &wp, &vhost))) return retcode;   if (FAILED(retcode=vhost->GetRootElement(&root))) return retcode; return S_OK; } As you can see the CreateHostFromXaml function of IXRApplication accepts a structure named XRWindowCreateParams that control how the “plain old” GWES Window is created by the runtime. This structure is initialized inside the InitWindowParm method: // Initializes Windows parameters, can be overridden in the user class to change its appearance virtual void InitWindowParms(XRWindowCreateParams* wp) { wp->Style = WS_OVERLAPPED; wp->pTitle = windowtitle; wp->Left = 0; wp->Top = 0; } This method set up the window style, title and position. But the XRWindowCreateParams contains also other fields and, since the function is declared as virtual, we could initialize them inside our version of InitWindowParms: // add hook procedure to the standard windows creation parms virtual void InitWindowParms(XRWindowCreateParams* wp) { TClock<Clock>::InitWindowParms(wp);   wp->pHookProc=StaticHostHookProc; wp->pvUserParam=this; } This method calls the base class implementation (useful to not having to re-write some code, did I told you that I’m quite lazy?) and then initializes the pHookProc and pvUserParam members of the XRWindowsCreateParams structure. Those members will allow us to install a “hook” procedure that will be called each time the GWES window “hosting” our Silverlight for Windows Embedded UI receives a message. We can declare a hook procedure inside our Clock class: // static hook procedure static BOOL CALLBACK StaticHostHookProc(VOID* pv,HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { ... } You should notice two things here. First that the function is declared as static. This is required because a non-static function has a “hidden” parameters, that is the “this” pointer of our object. Having an extra parameter is not allowed for the type defined for the pHookProc member of the XRWindowsCreateParams struct and so we should implement our hook procedure as static. But in a static procedure we will not have a this pointer. How could we access the data member of our class? Here’s the second thing to notice. We initialized also the pvUserParam of the XRWindowsCreateParams struct. We set it to our this pointer. This value will be passed as the first parameter of the hook procedure. In this way we can retrieve our this pointer and use it to call a non-static version of our hook procedure: // static hook procedure static BOOL CALLBACK StaticHostHookProc(VOID* pv,HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { return ((Clock*)pv)->HostHookProc(hwnd,Msg,wParam,lParam,pRetVal); } Inside our non-static hook procedure we will have access to our this pointer and we will be able to update our clock: // hook procedure (handles timers) BOOL HostHookProc(HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { switch (Msg) { case WM_TIMER: if (wParam==IDT_CLOCKUPDATE) UpdateClock(); *pRetVal=0; return TRUE; } return FALSE; } The UpdateClock member function will update the text inside our TextBlocks and rotate the hands to reflect current time: // udates Hands positions and labels HRESULT UpdateClock() { SYSTEMTIME time; HRESULT retcode;   GetLocalTime(&time);   //updates the text fields TCHAR timebuffer[32];   _itow(time.wSecond,timebuffer,10);   SecondsText->SetText(timebuffer);   _itow(time.wMinute,timebuffer,10);   MinutesText->SetText(timebuffer);   _itow(time.wHour,timebuffer,10);   HoursText->SetText(timebuffer);   if (FAILED(retcode=RotateHand(((float)time.wSecond)*6-90,SecondsHand))) return retcode;   if (FAILED(retcode=RotateHand(((float)time.wMinute)*6-90,MinutesHand))) return retcode;   if (FAILED(retcode=RotateHand(((float)(time.wHour%12))*30-90,HoursHand))) return retcode;   return S_OK; } The function retrieves current time, convert hours, minutes and seconds to strings and display those strings inside the three TextBlocks that we put inside our clock hands. Then it rotates the hands to position them at the right angle (angles are in degrees and we have to subtract 90 degrees because 0 degrees means horizontal on Silverlight for Windows Embedded and usually a clock 0 is in the top position of the dial. The code of the RotateHand function uses transforms to rotate our clock hands on the screen: // rotates a Hand HRESULT RotateHand(float angle,IXRFrameworkElement* Hand) { HRESULT retcode; IXRRotateTransformPtr rotatetransform; IXRApplicationPtr app;   if (FAILED(retcode=GetXRApplicationInstance(&app))) return retcode;   if (FAILED(retcode=app->CreateObject(IID_IXRRotateTransform,&rotatetransform))) return retcode;     if (FAILED(retcode=rotatetransform->SetAngle(angle))) return retcode;   if (FAILED(retcode=rotatetransform->SetCenterX(0.0))) return retcode;   float height;   if (FAILED(retcode==Hand->GetActualHeight(&height))) return retcode;   if (FAILED(retcode=rotatetransform->SetCenterY(height/2))) return retcode; if (FAILED(retcode=Hand->SetRenderTransform(rotatetransform))) return retcode;   return S_OK; } It creates a IXRotateTransform object, set its rotation angle and origin (the default origin is at the top-left corner of our Grid panel, we move it in the vertical center to keep the hand rotating around a single point in a more “clock like” way. Then we can apply the transform to our UI object using SetRenderTransform. Every UI element (derived from IXRFrameworkElement) can be rotated! And using different subclasses of IXRTransform also moved, scaled, skewed and distorted in many ways. You can also concatenate multiple transforms and apply them at once suing a IXRTransformGroup object. The XAML engine uses vector graphics and object will not look “pixelated” when they are rotated or scaled. As usual you can download the code here: http://cid-9b7b0aefe3514dc5.skydrive.live.com/self.aspx/.Public/Clock.zip If you read up to (down to?) this point you seem to be interested in Silverlight for Windows Embedded. If you want me to discuss some specific topic, please feel free to point it out in the comments! Technorati Tags: Silverlight for Windows Embedded,Windows CE

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  • Point inside Oriented Bounding Box?

    - by Milo
    I have an OBB2D class based on SAT. This is my point in OBB method: public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * (x - center.x)); float newx = (float) (Math.cos(angle) * (x - center.x) - Math.sin(angle) * (y - center.y)); return (newy > center.y - (getHeight() / 2)) && (newy < center.y + (getHeight() / 2)) && (newx > center.x - (getWidth() / 2)) && (newx < center.x + (getWidth() / 2)); } public boolean pointInside(Vector2D v) { return pointInside(v.x,v.y); } Here is the rest of the class; the parts that pertain: public class OBB2D { private Vector2D projVec = new Vector2D(); private static Vector2D projAVec = new Vector2D(); private static Vector2D projBVec = new Vector2D(); private static Vector2D tempNormal = new Vector2D(); private Vector2D deltaVec = new Vector2D(); private ArrayList<Vector2D> collisionPoints = new ArrayList<Vector2D>(); // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(float centerx, float centery, float w, float h, float angle) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(centerx,centery,w,h,angle); } public OBB2D(float left, float top, float width, float height) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(left + (width / 2), top + (height / 2),width,height,0.0f); } public void set(float centerx,float centery,float w, float h,float angle) { float vxx = (float)Math.cos(angle); float vxy = (float)Math.sin(angle); float vyx = (float)-Math.sin(angle); float vyy = (float)Math.cos(angle); vxx *= w / 2; vxy *= (w / 2); vyx *= (h / 2); vyy *= (h / 2); corner[0].x = centerx - vxx - vyx; corner[0].y = centery - vxy - vyy; corner[1].x = centerx + vxx - vyx; corner[1].y = centery + vxy - vyy; corner[2].x = centerx + vxx + vyx; corner[2].y = centery + vxy + vyy; corner[3].x = centerx - vxx + vyx; corner[3].y = centery - vxy + vyy; this.center.x = centerx; this.center.y = centery; this.angle = angle; computeAxes(); extents.x = w / 2; extents.y = h / 2; computeBoundingRect(); } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0].x = corner[1].x - corner[0].x; axis[0].y = corner[1].y - corner[0].y; axis[1].x = corner[3].x - corner[0].x; axis[1].y = corner[3].y - corner[0].y; // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { float l = axis[a].length(); float ll = l * l; axis[a].x = axis[a].x / ll; axis[a].y = axis[a].y / ll; origin[a] = corner[0].dot(axis[a]); } } public void computeBoundingRect() { boundingRect.left = JMath.min(JMath.min(corner[0].x, corner[3].x), JMath.min(corner[1].x, corner[2].x)); boundingRect.top = JMath.min(JMath.min(corner[0].y, corner[1].y),JMath.min(corner[2].y, corner[3].y)); boundingRect.right = JMath.max(JMath.max(corner[1].x, corner[2].x), JMath.max(corner[0].x, corner[3].x)); boundingRect.bottom = JMath.max(JMath.max(corner[2].y, corner[3].y),JMath.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(rect.centerX(),rect.centerY(),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } public void moveTo(float centerx, float centery) { float cx,cy; cx = center.x; cy = center.y; deltaVec.x = centerx - cx; deltaVec.y = centery - cy; for (int c = 0; c < 4; ++c) { corner[c].x += deltaVec.x; corner[c].y += deltaVec.y; } boundingRect.left += deltaVec.x; boundingRect.top += deltaVec.y; boundingRect.right += deltaVec.x; boundingRect.bottom += deltaVec.y; this.center.x = centerx; this.center.y = centery; computeAxes(); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center.x,center.y,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center.x,center.y,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } public static float distance(float ax, float ay,float bx, float by) { if (ax < bx) return bx - ay; else return ax - by; } public Vector2D project(float ax, float ay) { projVec.x = Float.MAX_VALUE; projVec.y = Float.MIN_VALUE; for (int i = 0; i < corner.length; ++i) { float dot = Vector2D.dot(corner[i].x,corner[i].y,ax,ay); projVec.x = JMath.min(dot, projVec.x); projVec.y = JMath.max(dot, projVec.y); } return projVec; } public Vector2D getCorner(int c) { return corner[c]; } public int getNumCorners() { return corner.length; } public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * (x - center.x)); float newx = (float) (Math.cos(angle) * (x - center.x) - Math.sin(angle) * (y - center.y)); return (newy > center.y - (getHeight() / 2)) && (newy < center.y + (getHeight() / 2)) && (newx > center.x - (getWidth() / 2)) && (newx < center.x + (getWidth() / 2)); } public boolean pointInside(Vector2D v) { return pointInside(v.x,v.y); } public ArrayList<Vector2D> getCollsionPoints(OBB2D b) { collisionPoints.clear(); for(int i = 0; i < corner.length; ++i) { if(b.pointInside(corner[i])) { collisionPoints.add(corner[i]); } } for(int i = 0; i < b.corner.length; ++i) { if(pointInside(b.corner[i])) { collisionPoints.add(b.corner[i]); } } return collisionPoints; } }; What could be wrong? When I getCollisionPoints for 2 OBBs I know are penetrating, it returns no points. Thanks

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  • Point of contact of 2 OBBs?

    - by Milo
    I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the point of contact when I hit a wall. Here is my OBB class: public class OBB2D { private Vector2D projVec = new Vector2D(); private static Vector2D projAVec = new Vector2D(); private static Vector2D projBVec = new Vector2D(); private static Vector2D tempNormal = new Vector2D(); private Vector2D deltaVec = new Vector2D(); // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(float centerx, float centery, float w, float h, float angle) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(centerx,centery,w,h,angle); } public OBB2D(float left, float top, float width, float height) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(left + (width / 2), top + (height / 2),width,height,0.0f); } public void set(float centerx,float centery,float w, float h,float angle) { float vxx = (float)Math.cos(angle); float vxy = (float)Math.sin(angle); float vyx = (float)-Math.sin(angle); float vyy = (float)Math.cos(angle); vxx *= w / 2; vxy *= (w / 2); vyx *= (h / 2); vyy *= (h / 2); corner[0].x = centerx - vxx - vyx; corner[0].y = centery - vxy - vyy; corner[1].x = centerx + vxx - vyx; corner[1].y = centery + vxy - vyy; corner[2].x = centerx + vxx + vyx; corner[2].y = centery + vxy + vyy; corner[3].x = centerx - vxx + vyx; corner[3].y = centery - vxy + vyy; this.center.x = centerx; this.center.y = centery; this.angle = angle; computeAxes(); extents.x = w / 2; extents.y = h / 2; computeBoundingRect(); } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0].x = corner[1].x - corner[0].x; axis[0].y = corner[1].y - corner[0].y; axis[1].x = corner[3].x - corner[0].x; axis[1].y = corner[3].y - corner[0].y; // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { float l = axis[a].length(); float ll = l * l; axis[a].x = axis[a].x / ll; axis[a].y = axis[a].y / ll; origin[a] = corner[0].dot(axis[a]); } } public void computeBoundingRect() { boundingRect.left = JMath.min(JMath.min(corner[0].x, corner[3].x), JMath.min(corner[1].x, corner[2].x)); boundingRect.top = JMath.min(JMath.min(corner[0].y, corner[1].y),JMath.min(corner[2].y, corner[3].y)); boundingRect.right = JMath.max(JMath.max(corner[1].x, corner[2].x), JMath.max(corner[0].x, corner[3].x)); boundingRect.bottom = JMath.max(JMath.max(corner[2].y, corner[3].y),JMath.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(rect.centerX(),rect.centerY(),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } public void moveTo(float centerx, float centery) { float cx,cy; cx = center.x; cy = center.y; deltaVec.x = centerx - cx; deltaVec.y = centery - cy; for (int c = 0; c < 4; ++c) { corner[c].x += deltaVec.x; corner[c].y += deltaVec.y; } boundingRect.left += deltaVec.x; boundingRect.top += deltaVec.y; boundingRect.right += deltaVec.x; boundingRect.bottom += deltaVec.y; this.center.x = centerx; this.center.y = centery; computeAxes(); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center.x,center.y,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center.x,center.y,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } public static float distance(float ax, float ay,float bx, float by) { if (ax < bx) return bx - ay; else return ax - by; } public Vector2D project(float ax, float ay) { projVec.x = Float.MAX_VALUE; projVec.y = Float.MIN_VALUE; for (int i = 0; i < corner.length; ++i) { float dot = Vector2D.dot(corner[i].x,corner[i].y,ax,ay); projVec.x = JMath.min(dot, projVec.x); projVec.y = JMath.max(dot, projVec.y); } return projVec; } public Vector2D getCorner(int c) { return corner[c]; } public int getNumCorners() { return corner.length; } public static float collisionResponse(OBB2D a, OBB2D b, Vector2D outNormal) { float depth = Float.MAX_VALUE; for (int i = 0; i < a.getNumCorners() + b.getNumCorners(); ++i) { Vector2D edgeA; Vector2D edgeB; if(i >= a.getNumCorners()) { edgeA = b.getCorner((i + b.getNumCorners() - 1) % b.getNumCorners()); edgeB = b.getCorner(i % b.getNumCorners()); } else { edgeA = a.getCorner((i + a.getNumCorners() - 1) % a.getNumCorners()); edgeB = a.getCorner(i % a.getNumCorners()); } tempNormal.x = edgeB.x -edgeA.x; tempNormal.y = edgeB.y - edgeA.y; tempNormal.normalize(); projAVec.equals(a.project(tempNormal.x,tempNormal.y)); projBVec.equals(b.project(tempNormal.x,tempNormal.y)); float distance = OBB2D.distance(projAVec.x, projAVec.y,projBVec.x,projBVec.y); if (distance > 0.0f) { return 0.0f; } else { float d = Math.abs(distance); if (d < depth) { depth = d; outNormal.equals(tempNormal); } } } float dx,dy; dx = b.getCenter().x - a.getCenter().x; dy = b.getCenter().y - a.getCenter().y; float dot = Vector2D.dot(dx,dy,outNormal.x,outNormal.y); if(dot > 0) { outNormal.x = -outNormal.x; outNormal.y = -outNormal.y; } return depth; } public Vector2D getMoveDeltaVec() { return deltaVec; } }; Thanks!

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  • CodePlex Daily Summary for Tuesday, May 04, 2010

    CodePlex Daily Summary for Tuesday, May 04, 2010New ProjectsAlbum photo de club - Club's Photos Album: Un album photos permettant d'afficher les photos et le détails des membres d'un club - Photo album allowing to view photos and details of the membersBlog.Net Blogging Components: Blog.Net server-side blogging components to add a blog to your current ASP.NET website.FilePirate - Really Advanced LAN File Sharing: Really Advanced, yet super easy, LAN Party File Sharing written using the .Net Framework and C#. Ditch DirectConnect or Windows File Sharing at y...Fisiogest: Programa de gestión de una clínica de fisioterapiaIdeaNMR: An online repository of NMR experiment automated setups with wiki type documentation library and client program providing automated experiment setu...Introducción a Unity: Código de ejemplo del uso de Unity en diferentes situaciones. - Registro de clases, instancias e interfaces. - Resolución de clases, instancias e...Iowa City .NET Developers: This is the project site for the Iowa City .NET Developers.isanywhere: A command line utility to see if one or more files (given a filemask) are to be found anywhere inside a specific directory, or elsewhere inside one...LczCode: lczLog4net udp logs viewer: UdpLogViewer is a .NET 4 WinForm application that receives udp messages from log4net and shows them in a grid. It is possible to filter them or sh...New Silverlight XPS Viewer (In Sl4): New Silverlight XPS viewer Novuz: Novuz is a usenet indexer and reporter. It's developed both in Visual Studio 2010 and MonoDevelop, one of the key features of Novuz is that it sho...PodSnatch: PodSnatch is a podcast client that makes it easy to download rss-enclosures. Multiple simultaneous downloads enabled by threading. GUI is built wi...Robot Shootans: A simple top down shooter game where the player has to kill robots running at them. Written in C++ using SDL with various extentionsSharePoint Rsync List: This program will syncronize files and directories from and unc/local/sharepoint to a SharePoint 2007 or 2010 server. Supports of to 2GB files and ...SignInAndStorageLib: SignInAndStorageLib makes properly handling both sign in and storage issues in Xbox 360 XBLIG XNA games simple. Written in C#, SignInAndStorageLib...SilverBBS: ANSI-style bbs experience delivered via Silverlight. Silverlight flip-down counter: A Silverlight widget that enables you to count down towards a preconfigured event on a configured date.SmartieFly: Smartie Fly is a quiz software program written in C# using Silverlight. It uses SQL Server as a backend database. VS2010 Framework Driven Testing: CodedUITests generate a lot of code, and they break on every change to the object under test. Goals: - write new tests manually, but with as litt...WMediaCatalog: Advanced multimedia cataloguer. Allows users to keep their musical collections well organized and provides flexible methods of filtering, serarching WPathFinder: A simple path management application for windows. Functionality includes: - Add/remove/change path entries easily. - Search for all instances of a...Yasminoku: Yasminoku is an open source "Sudoku" alike game totally written in DHTML (JavaScript, CSS and HTML) that uses mouse. Includes sudoku solver. This c...New ReleasesAlbum photo de club - Club's Photos Album: App - version 0.4: version 0.4 - Critère d'affichage des membres : nom, année, ville - Navigation entre les images d'un membres - Navigation entre les membres - Affi...Album photo de club - Club's Photos Album: Code - Version 0.4: Code source de la version 0.4BigDecimal: Concept Evaluation Release 2 (BigDecimals): This in the second updates release of BigDecimals. It has the four simple arithmetic rules Addition, Subtract, Multiple and Division.CBM-Command: 2010-05-03: New features in this build Keyboard Shortcuts Panel Swapping Panel Toggling On/Off Toggling 40/80 Columns Confirming Quit Confirming GO64...Directory Linker: Directory Linker 2: This release introduces Undo Support and Symbolic File Link support. More details can be found here http://www.humblecoder.co.uk/?p=141DotNetNuke Skins Pack: DotNetNuke 80 Skins Pack: This released is the first for DNN 4 & 5 with Skin Token Design (legacy skin support on DNN 4 & 5)DTLoggedExec: 1.0.0.0: -FIRST NON-BETA RELEASE! :) -Code cleaned up -Added SetPackageInfo method to ILogProvider interface to make easier future improvements -Deprecated...GenerateTypedBamApi: Version 2.1: Changes in this release: NEW: Support for Office Data Connectivity Components 2010 NEW: Include both x86 and x64 EXE's due to lack of support in ...HobbyBrew Mobile: Beta 1 Refresh: Risolto bug circa il salvataggio di ricette (veniva impostato scorrettamente che si trattava di Mash Design "infusione" se ri-aperte con hobbyBrew)...Home Access Plus+: v4.2: Version 4.2 Added Overrides into the Booking System Some slight CSS changes to the Help Desk Updated the config tool to work anywhere on the LA...Hubble.Net - Open source full-text search database: V0.8.3.0: V0.8.3.0 Show server version in about dialog. Fix a bug of deleting querycache files. V0.8.2.9 Change sql client to support userid and password Ch...IdeaNMR: IdeaNMR Client: This is a client program with an example package.kdar: KDAR 0.0.21: KDAR - Kernel Debugger Anti Rootkit - signature's bases updated - usability increased - NDIS6 MINIPORT_BLOCK checks addedLightWeight Application Server: 0.4.1: One step further to beta - yet another release for c# developers audience only. Changes: 1. API - added a LWAS.Infrastructure.Storage service to d...Log4net udp logs viewer: UdpLogViewer 1.0: First release of UdpLogViewer, version 1.0.MDownloader: MDownloader-0.15.11.58370: Fixed minor bugs.Metabolite Enterprise Libraries for EPiServer CMS using Page Type Builder: Metabolite Enterprise Libraries 1.2 Beta 2: This is the beta release of the Metabolite Enterprise Libraries 1.2 Beta 2 for use with EPiServer 6 and Page Type Builder 1.2 Beta 2.Microsoft Silverlight Analytics Framework: Version 1.4.3 Installer: Pre-release Installer for Visual Studio 2010 and Expression Blend 4 RCSupports both Silverlight 3 and Silverlight 4 Release NotesFixed null referen...MultipointTUIO: Multipoint SDK v1.5 Release: Rebuilt against v1.5 of the Microsoft Multipoint SDK, this mean Windows 7 support (and 64bit I think!)My Notepad: My Notepad: This is the status of My Notepad until now. This is many built in features but has to undergo a lot of modifications. The release does not include ...New Silverlight XPS Viewer (In Sl4): Silverlight XPS Viewer: Background: During my development last week I was working on a Silverlight based XPS viewer. During this viewer we came to a situation in which the...NSIS Autorun: NSIS Autorun 0.1.6: This release includes source code, executable binary, files and example materials.Open Diagram: Open Diagram 5.0 Beta May 2010: This is the first beta release of Open Diagram 5.0. Select Crainiate.Diagramming.Examples.Forms as the startup project to view the current Class D...Pocket Wiki: PC Wiki (zip) 1.0.1: PC Version of Pocket Wiki. Unzip and run. Requires .NET Framework 2.0Pocket Wiki: Pocket Wiki 1.0.1 (cab): Pocket Wiki cab installation - requires DotNet 2.0 or greater. Default wiki language is "slash" - a syntax I created that is easy to type on keyboa...Pocket Wiki: Pocket Wiki.sbp: Pocket Wiki Source Code (version .72) - Basic4PPCPublish to Photo Frame: 1.0.2.0: This version adds: add borders to portrait images, for photo frames that crop them incorrectly.Reflection Studio: Reflection Studio 0.1: First download release, it contains a lot of things but allways in beta version. Hope you will like the preview.SharePoint 2010 PowerShell Scripts & Utilities: PSSP2010 Utils 0.1: This is the initial release with SPInstallUtils.psm1 module. This module includes Get-SPPrerequisites and New-SPInstallPackage cmdlets. Refer to th...Silverlight 4.0 Popup Menu: Context Menu for Silverlight 4.0 v1.1 Beta: Multilevel menus are now supported. Added design time support for the PopupMenuItem elements. The project is now under Subversion.Silverlight flip-down counter: FlipDownCounter v1.0: The final release of the Silverlight flip-down counter. Please refer to the included readme file for information on how to use the counter.Stratosphere: Stratosphere 1.0.0.1: Moved scalable block file system implementation to Stratosphere.FileSystemSystem.AddIn Pipeline Builder: Pipeline Builder 1.2: Lots of improvements from the CTP, version 1.0: - Added dialogue for possible overwrite if the file has changed: possibility of ignoring changes (p...ThoughtWorks Cruise Notification Interceptor: 1.0.1: Fixed an issue with the regex that parses the incoming notification. This issue would send failure messages when the build was "fixed".ThreadSafeControls: ThreadSafeControls v0.1: This is the first binary release of the ThreadSafeControls library. I'll call it a pre-alpha release.TracerX Logger/Viewer for .NET: 4.0: View this CodeProject article for documentation on how to use the latest version of the Logger. About the DownloadsVersion: 4.0.1005.1163 Changese...VCC: Latest build, v2.1.30503.0: Automatic drop of latest buildVisual Studio DSite: Lottery Game (Visual C++ 2008): An advanced lottery game made in visual c 2008.VivoSocial: VivoSocial 7.1.3: Version 7.1.3 of VivoSocial has been released. If you experienced any issues with the previous version, please update your modules to the 7.1.3 rel...Xrns2XMod: Xrns2XMod 1.0: Features added Conversion of all possible convertible features between Renoise and MOD / XM. FlacBox lib updated (thanks to Yuri) NAudio lib in...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: Databasepatterns & practices – Enterprise LibrarySilverlight ToolkitiTuner - The iTunes CompanionWindows Presentation Foundation (WPF)ASP.NETDotNetNuke® Community EditionMost Active ProjectsIonics Isapi Rewrite Filterpatterns & practices – Enterprise LibraryRawrHydroServer - CUAHSI Hydrologic Information System ServerAJAX Control Frameworkpatterns & practices: Azure Security GuidanceNB_Store - Free DotNetNuke Ecommerce Catalog ModuleBlogEngine.NETTinyProjectDambach Linear Algebra Framework

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  • Performance Optimization &ndash; It Is Faster When You Can Measure It

    - by Alois Kraus
    Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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  • C#: My World Clock

    - by Bruce Eitman
    [Placeholder:  I will post the entire project soon] I have been working on cleaning my office of 8 years of stuff from several engineers working on many projects.  It turns out that we have a few extra single board computers with displays, so at the end of the day last Friday I though why not create a little application to display the time, you know, a clock.  How difficult could that be?  It turns out that it is quite simple – until I decided to gold plate the project by adding time displays for our offices around the world. I decided to use C#, which actually made creating the main clock quite easy.   The application was simply a text box and a timer.  I set the timer to fire a couple of times a second, and when it does use a DateTime object to get the current time and retrieve a string to display. And I could have been done, but of course that gold plating came up.   Seems simple enough, simply offset the time from the local time to the location that I want the time for and display it.    Sure enough, I had the time displayed for UK, Italy, Kansas City, Japan and China in no time at all. But it is October, and for those of us still stuck with Daylight Savings Time, we know that the clocks are about to change.   My first attempt was to simply check to see if the local time was DST or Standard time, then change the offset for China.  China doesn’t have Daylight Savings Time. If you know anything about the time changes around the world, you already know that my plan is flawed – in a big way.   It turns out that the transitions in and out of DST take place at different times around the world.   If you didn’t know that, do a quick search for “Daylight Savings” and you will find many WEB sites dedicated to tracking the time changes dates, and times. Now the real challenge of this application; how do I programmatically find out when the time changes occur and handle them correctly?  After a considerable amount of research it turns out that the solution is to read the data from the registry and parse it to figure out when the time changes occur. Reading Time Change Information from the Registry Reading the data from the registry is simple, using the data is a little more complicated.  First, reading from the registry can be done like:             byte[] binarydata = (byte[])Registry.GetValue("HKEY_LOCAL_MACHINE\\Time Zones\\Eastern Standard Time", "TZI", null);   Where I have hardcoded the registry key for example purposes, but in the end I will use some variables.   We now have a binary blob with the data, but it needs to be converted to use the real data.   To start we will need a couple of structs to hold the data and make it usable.   We will need a SYSTEMTIME and REG_TZI_FORMAT.   You may have expected that we would need a TIME_ZONE_INFORMATION struct, but we don’t.   The data is stored in the registry as a REG_TZI_FORMAT, which excludes some of the values found in TIME_ZONE_INFORMATION.     struct SYSTEMTIME     {         internal short wYear;         internal short wMonth;         internal short wDayOfWeek;         internal short wDay;         internal short wHour;         internal short wMinute;         internal short wSecond;         internal short wMilliseconds;     }       struct REG_TZI_FORMAT     {         internal long Bias;         internal long StdBias;         internal long DSTBias;         internal SYSTEMTIME StandardStart;         internal SYSTEMTIME DSTStart;     }   Now we need to convert the binary blob to a REG_TZI_FORMAT.   To do that I created the following helper functions:         private void BinaryToSystemTime(ref SYSTEMTIME ST, byte[] binary, int offset)         {             ST.wYear = (short)(binary[offset + 0] + (binary[offset + 1] << 8));             ST.wMonth = (short)(binary[offset + 2] + (binary[offset + 3] << 8));             ST.wDayOfWeek = (short)(binary[offset + 4] + (binary[offset + 5] << 8));             ST.wDay = (short)(binary[offset + 6] + (binary[offset + 7] << 8));             ST.wHour = (short)(binary[offset + 8] + (binary[offset + 9] << 8));             ST.wMinute = (short)(binary[offset + 10] + (binary[offset + 11] << 8));             ST.wSecond = (short)(binary[offset + 12] + (binary[offset + 13] << 8));             ST.wMilliseconds = (short)(binary[offset + 14] + (binary[offset + 15] << 8));         }             private REG_TZI_FORMAT ConvertFromBinary(byte[] binarydata)         {             REG_TZI_FORMAT RTZ = new REG_TZI_FORMAT();               RTZ.Bias = binarydata[0] + (binarydata[1] << 8) + (binarydata[2] << 16) + (binarydata[3] << 24);             RTZ.StdBias = binarydata[4] + (binarydata[5] << 8) + (binarydata[6] << 16) + (binarydata[7] << 24);             RTZ.DSTBias = binarydata[8] + (binarydata[9] << 8) + (binarydata[10] << 16) + (binarydata[11] << 24);             BinaryToSystemTime(ref RTZ.StandardStart, binarydata, 4 + 4 + 4);             BinaryToSystemTime(ref RTZ.DSTStart, binarydata, 4 + 16 + 4 + 4);               return RTZ;         }   I am the first to admit that there may be a better way to get the settings from the registry and into the REG_TXI_FORMAT, but I am not a great C# programmer which I have said before on this blog.   So sometimes I chose brute force over elegant. Now that we have the Bias information and the start date information, we can start to make sense of it.   The bias is an offset, in minutes, from local time (if already in local time for the time zone in question) to get to UTC – or as Microsoft defines it: UTC = local time + bias.  Standard bias is an offset to adjust for standard time, which I think is usually zero.   And DST bias is and offset to adjust for daylight savings time. Since we don’t have the local time for a time zone other than the one that the computer is set to, what we first need to do is convert local time to UTC, which is simple enough using:                 DateTime.Now.ToUniversalTime(); Then, since we have UTC we need to do a little math to alter the formula to: local time = UTC – bias.  In other words, we need to subtract the bias minutes. I am ahead of myself though, the standard and DST start dates really aren’t dates.   Instead they indicate the month, day of week and week number of the time change.   The dDay member of SYSTEM time will be set to the week number of the date change indicating that the change happens on the first, second… day of week of the month.  So we need to convert them to dates so that we can determine which bias to use, and when to change to a different bias.   To do that, I wrote the following function:         private DateTime SystemTimeToDateTimeStart(SYSTEMTIME Time, int Year)         {             DayOfWeek[] Days = { DayOfWeek.Sunday, DayOfWeek.Monday, DayOfWeek.Tuesday, DayOfWeek.Wednesday, DayOfWeek.Thursday, DayOfWeek.Friday, DayOfWeek.Saturday };             DateTime InfoTime = new DateTime(Year, Time.wMonth, Time.wDay == 1 ? 1 : ((Time.wDay - 1) * 7) + 1, Time.wHour, Time.wMinute, Time.wSecond, DateTimeKind.Utc);             DateTime BestGuess = InfoTime;             while (BestGuess.DayOfWeek != Days[Time.wDayOfWeek])             {                 BestGuess = BestGuess.AddDays(1);             }             return BestGuess;         }   SystemTimeToDateTimeStart gets two parameters; a SYSTEMTIME and a year.   The reason is that we will try this year and next year because we are interested in start dates that are in the future, not the past.  The function starts by getting a new Datetime with the first possible date and then looking for the correct date. Using the start dates, we can then determine the correct bias to use, and the next date that time will change:             NextTimeChange = StandardChange;             CurrentBias = TimezoneSettings.Bias + TimezoneSettings.DSTBias;             if (DSTChange.Year != 1 && StandardChange.Year != 1)             {                 if (DSTChange.CompareTo(StandardChange) < 0)                 {                     NextTimeChange = DSTChange;                     CurrentBias = TimezoneSettings.StdBias + TimezoneSettings.Bias;                 }             }             else             {                 // I don't like this, but it turns out that China Standard Time                 // has a DSTBias of -60 on every Windows system that I tested.                 // So, if no DST transitions, then just use the Bias without                 // any offset                 CurrentBias = TimezoneSettings.Bias;             }   Note that some time zones do not change time, in which case the years will remain set to 1.   Further, I found that the registry settings are actually wrong in that the DST Bias is set to -60 for China even though there is not DST in China, so I ignore the standard and DST bias for those time zones. There is one thing that I have not solved, and don’t plan to solve.  If the time zone for this computer changes, this application will not update the clock using the new time zone.  I tell  you this because you may need to deal with it – I do not because I won’t let the user get to the control panel applet to change the timezone. Copyright © 2012 – Bruce Eitman All Rights Reserved

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  • C#/.NET &ndash; Finding an Item&rsquo;s Index in IEnumerable&lt;T&gt;

    - by James Michael Hare
    Sorry for the long blogging hiatus.  First it was, of course, the holidays hustle and bustle, then my brother and his wife gave birth to their son, so I’ve been away from my blogging for two weeks. Background: Finding an item’s index in List<T> is easy… Many times in our day to day programming activities, we want to find the index of an item in a collection.  Now, if we have a List<T> and we’re looking for the item itself this is trivial: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // can find the exact item using IndexOf() 5: var pos = list.IndexOf(64); This will return the position of the item if it’s found, or –1 if not.  It’s easy to see how this works for primitive types where equality is well defined.  For complex types, however, it will attempt to compare them using EqualityComparer<T>.Default which, in a nutshell, relies on the object’s Equals() method. So what if we want to search for a condition instead of equality?  That’s also easy in a List<T> with the FindIndex() method: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // finds index of first even number or -1 if not found. 5: var pos = list.FindIndex(i => i % 2 == 0);   Problem: Finding an item’s index in IEnumerable<T> is not so easy... This is all well and good for lists, but what if we want to do the same thing for IEnumerable<T>?  A collection of IEnumerable<T> has no indexing, so there’s no direct method to find an item’s index.  LINQ, as powerful as it is, gives us many tools to get us this information, but not in one step.  As with almost any problem involving collections, there are several ways to accomplish the same goal.  And once again as with almost any problem involving collections, the choice of the solution somewhat depends on the situation. So let’s look at a few possible alternatives.  I’m going to express each of these as extension methods for simplicity and consistency. Solution: The TakeWhile() and Count() combo One of the things you can do is to perform a TakeWhile() on the list as long as your find condition is not true, and then do a Count() of the items it took.  The only downside to this method is that if the item is not in the list, the index will be the full Count() of items, and not –1.  So if you don’t know the size of the list beforehand, this can be confusing. 1: // a collection of extra extension methods off IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item in the collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // note if item not found, result is length and not -1! 8: return list.TakeWhile(i => !finder(i)).Count(); 9: } 10: } Personally, I don’t like switching the paradigm of not found away from –1, so this is one of my least favorites.  Solution: Select with index Many people don’t realize that there is an alternative form of the LINQ Select() method that will provide you an index of the item being selected: 1: list.Select( (item,index) => do something here with the item and/or index... ) This can come in handy, but must be treated with care.  This is because the index provided is only as pertains to the result of previous operations (if any).  For example: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // you'd hope this would give you the indexes of the even numbers 5: // which would be 2, 3, 8, but in reality it gives you 0, 1, 2 6: list.Where(item => item % 2 == 0).Select((item,index) => index); The reason the example gives you the collection { 0, 1, 2 } is because the where clause passes over any items that are odd, and therefore only the even items are given to the select and only they are given indexes. Conversely, we can’t select the index and then test the item in a Where() clause, because then the Where() clause would be operating on the index and not the item! So, what we have to do is to select the item and index and put them together in an anonymous type.  It looks ugly, but it works: 1: // extensions defined on IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // finds an item in a collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // if you don't name the anonymous properties they are the variable names 8: return list.Select((item, index) => new { item, index }) 9: .Where(p => finder(p.item)) 10: .Select(p => p.index + 1) 11: .FirstOrDefault() - 1; 12: } 13: }     So let’s look at this, because i know it’s convoluted: First Select() joins the items and their indexes into an anonymous type. Where() filters that list to only the ones matching the predicate. Second Select() picks the index of the matches and adds 1 – this is to distinguish between not found and first item. FirstOrDefault() returns the first item found from the previous clauses or default (zero) if not found. Subtract one so that not found (zero) will be –1, and first item (one) will be zero. The bad thing is, this is ugly as hell and creates anonymous objects for each item tested until it finds the match.  This concerns me a bit but we’ll defer judgment until compare the relative performances below. Solution: Convert ToList() and use FindIndex() This solution is easy enough.  We know any IEnumerable<T> can be converted to List<T> using the LINQ extension method ToList(), so we can easily convert the collection to a list and then just use the FindIndex() method baked into List<T>. 1: // a collection of extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // find the index of an item in the collection similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: return list.ToList().FindIndex(finder); 8: } 9: } This solution is simplicity itself!  It is very concise and elegant and you need not worry about anyone misinterpreting what it’s trying to do (as opposed to the more convoluted LINQ methods above). But the main thing I’m concerned about here is the performance hit to allocate the List<T> in the ToList() call, but once again we’ll explore that in a second. Solution: Roll your own FindIndex() for IEnumerable<T> Of course, you can always roll your own FindIndex() method for IEnumerable<T>.  It would be a very simple for loop which scans for the item and counts as it goes.  There’s many ways to do this, but one such way might look like: 1: // extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item matching a predicate in the enumeration, much like List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: int index = 0; 8: foreach (var item in list) 9: { 10: if (finder(item)) 11: { 12: return index; 13: } 14:  15: index++; 16: } 17:  18: return -1; 19: } 20: } Well, it’s not quite simplicity, and those less familiar with LINQ may prefer it since it doesn’t include all of the lambdas and behind the scenes iterators that come with deferred execution.  But does having this long, blown out method really gain us much in performance? Comparison of Proposed Solutions So we’ve now seen four solutions, let’s analyze their collective performance.  I took each of the four methods described above and run them over 100,000 iterations of lists of size 10, 100, 1000, and 10000 and here’s the performance results.  Then I looked for targets at the begining of the list (best case), middle of the list (the average case) and not in the list (worst case as must scan all of the list). Each of the times below is the average time in milliseconds for one execution as computer over the 100,000 iterations: Searches Matching First Item (Best Case)   10 100 1000 10000 TakeWhile 0.0003 0.0003 0.0003 0.0003 Select 0.0005 0.0005 0.0005 0.0005 ToList 0.0002 0.0003 0.0013 0.0121 Manual 0.0001 0.0001 0.0001 0.0001   Searches Matching Middle Item (Average Case)   10 100 1000 10000 TakeWhile 0.0004 0.0020 0.0191 0.1889 Select 0.0008 0.0042 0.0387 0.3802 ToList 0.0002 0.0007 0.0057 0.0562 Manual 0.0002 0.0013 0.0129 0.1255   Searches Where Not Found (Worst Case)   10 100 1000 10000 TakeWhile 0.0006 0.0039 0.0381 0.3770 Select 0.0012 0.0081 0.0758 0.7583 ToList 0.0002 0.0012 0.0100 0.0996 Manual 0.0003 0.0026 0.0253 0.2514   Notice something interesting here, you’d think the “roll your own” loop would be the most efficient, but it only wins when the item is first (or very close to it) regardless of list size.  In almost all other cases though and in particular the average case and worst case, the ToList()/FindIndex() combo wins for performance, even though it is creating some temporary memory to hold the List<T>.  If you examine the algorithm, the reason why is most likely because once it’s in a ToList() form, internally FindIndex() scans the internal array which is much more efficient to iterate over.  Thus, it takes a one time performance hit (not including any GC impact) to create the List<T> but after that the performance is much better. Summary If you’re concerned about too many throw-away objects, you can always roll your own FindIndex() method, but for sheer simplicity and overall performance, using the ToList()/FindIndex() combo performs best on nearly all list sizes in the average and worst cases.    Technorati Tags: C#,.NET,Litte Wonders,BlackRabbitCoder,Software,LINQ,List

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  • Applications: The mathematics of movement, Part 1

    - by TechTwaddle
    Before you continue reading this post, a suggestion; if you haven’t read “Programming Windows Phone 7 Series” by Charles Petzold, go read it. Now. If you find 150+ pages a little too long, at least go through Chapter 5, Principles of Movement, especially the section “A Brief Review of Vectors”. This post is largely inspired from this chapter. At this point I assume you know what vectors are, how they are represented using the pair (x, y), what a unit vector is, and given a vector how you would normalize the vector to get a unit vector. Our task in this post is simple, a marble is drawn at a point on the screen, the user clicks at a random point on the device, say (destX, destY), and our program makes the marble move towards that point and stop when it is reached. The tricky part of this task is the word “towards”, it adds a direction to our problem. Making a marble bounce around the screen is simple, all you have to do is keep incrementing the X and Y co-ordinates by a certain amount and handle the boundary conditions. Here, however, we need to find out exactly how to increment the X and Y values, so that the marble appears to move towards the point where the user clicked. And this is where vectors can be so helpful. The code I’ll show you here is not ideal, we’ll be working with C# on Windows Mobile 6.x, so there is no built-in vector class that I can use, though I could have written one and done all the math inside the class. I think it is trivial to the actual problem that we are trying to solve and can be done pretty easily once you know what’s going on behind the scenes. In other words, this is an excuse for me being lazy. The first approach, uses the function Atan2() to solve the “towards” part of the problem. Atan2() takes a point (x, y) as input, Atan2(y, x), note that y goes first, and then it returns an angle in radians. What angle you ask. Imagine a line from the origin (0, 0), to the point (x, y). The angle which Atan2 returns is the angle the positive X-axis makes with that line, measured clockwise. The figure below makes it clear, wiki has good details about Atan2(), give it a read. The pair (x, y) also denotes a vector. A vector whose magnitude is the length of that line, which is Sqrt(x*x + y*y), and a direction ?, as measured from positive X axis clockwise. If you’ve read that chapter from Charles Petzold’s book, this much should be clear. Now Sine and Cosine of the angle ? are special. Cosine(?) divides x by the vectors length (adjacent by hypotenuse), thus giving us a unit vector along the X direction. And Sine(?) divides y by the vectors length (opposite by hypotenuse), thus giving us a unit vector along the Y direction. Therefore the vector represented by the pair (cos(?), sin(?)), is the unit vector (or normalization) of the vector (x, y). This unit vector has a length of 1 (remember sin2(?) + cos2(?) = 1 ?), and a direction which is the same as vector (x, y). Now if I multiply this unit vector by some amount, then I will always get a point which is a certain distance away from the origin, but, more importantly, the point will always be on that line. For example, if I multiply the unit vector with the length of the line, I get the point (x, y). Thus, all we have to do to move the marble towards our destination point, is to multiply the unit vector by a certain amount each time and draw the marble, and the marble will magically move towards the click point. Now time for some code. The application, uses a timer based frame draw method to draw the marble on the screen. The timer is disabled initially and whenever the user clicks on the screen, the timer is enabled. The callback function for the timer follows the standard Update and Draw cycle. private double totLenToTravelSqrd = 0; private double startPosX = 0, startPosY = 0; private double destX = 0, destY = 0; private void Form1_MouseUp(object sender, MouseEventArgs e) {     destX = e.X;     destY = e.Y;     double x = marble1.x - destX;     double y = marble1.y - destY;     //calculate the total length to be travelled     totLenToTravelSqrd = x * x + y * y;     //store the start position of the marble     startPosX = marble1.x;     startPosY = marble1.y;     timer1.Enabled = true; } private void timer1_Tick(object sender, EventArgs e) {     UpdatePosition();     DrawMarble(); } Form1_MouseUp() method is called when ever the user touches and releases the screen. In this function we save the click point in destX and destY, this is the destination point for the marble and we also enable the timer. We store a few more values which we will use in the UpdatePosition() method to detect when the marble has reached the destination and stop the timer. So we store the start position of the marble and the square of the total length to be travelled. I’ll leave out the term ‘sqrd’ when speaking of lengths from now on. The time out interval of the timer is set to 40ms, thus giving us a frame rate of about ~25fps. In the timer callback, we update the marble position and draw the marble. We know what DrawMarble() does, so here, we’ll only look at how UpdatePosition() is implemented; private void UpdatePosition() {     //the vector (x, y)     double x = destX - marble1.x;     double y = destY - marble1.y;     double incrX=0, incrY=0;     double distanceSqrd=0;     double speed = 6;     //distance between destination and current position, before updating marble position     distanceSqrd = x * x + y * y;     double angle = Math.Atan2(y, x);     //Cos and Sin give us the unit vector, 6 is the value we use to magnify the unit vector along the same direction     incrX = speed * Math.Cos(angle);     incrY = speed * Math.Sin(angle);     marble1.x += incrX;     marble1.y += incrY;     //check for bounds     if ((int)marble1.x < MinX + marbleWidth / 2)     {         marble1.x = MinX + marbleWidth / 2;     }     else if ((int)marble1.x > (MaxX - marbleWidth / 2))     {         marble1.x = MaxX - marbleWidth / 2;     }     if ((int)marble1.y < MinY + marbleHeight / 2)     {         marble1.y = MinY + marbleHeight / 2;     }     else if ((int)marble1.y > (MaxY - marbleHeight / 2))     {         marble1.y = MaxY - marbleHeight / 2;     }     //distance between destination and current point, after updating marble position     x = destX - marble1.x;     y = destY - marble1.y;     double newDistanceSqrd = x * x + y * y;     //length from start point to current marble position     x = startPosX - (marble1.x);     y = startPosY - (marble1.y);     double lenTraveledSqrd = x * x + y * y;     //check for end conditions     if ((int)lenTraveledSqrd >= (int)totLenToTravelSqrd)     {         System.Console.WriteLine("Stopping because destination reached");         timer1.Enabled = false;     }     else if (Math.Abs((int)distanceSqrd - (int)newDistanceSqrd) < 4)     {         System.Console.WriteLine("Stopping because no change in Old and New position");         timer1.Enabled = false;     } } Ok, so in this function, first we subtract the current marble position from the destination point to give us a vector. The first three lines of the function construct this vector (x, y). The vector (x, y) has the same length as the line from (marble1.x, marble1.y) to (destX, destY) and is in the direction pointing from (marble1.x, marble1.y) to (destX, destY). Note that marble1.x and marble1.y denote the center point of the marble. Then we use Atan2() to get the angle which this vector makes with the positive X axis and use Cosine() and Sine() of that angle to get the unit vector along that same direction. We multiply this unit vector with 6, to get the values which the position of the marble should be incremented by. This variable, speed, can be experimented with and determines how fast the marble moves towards the destination. After this, we check for bounds to make sure that the marble stays within the screen limits and finally we check for the end condition and stop the timer. The end condition has two parts to it. The first case is the normal case, where the user clicks well inside the screen. Here, we stop when the total length travelled by the marble is greater than or equal to the total length to be travelled. Simple enough. The second case is when the user clicks on the very corners of the screen. Like I said before, the values marble1.x and marble1.y denote the center point of the marble. When the user clicks on the corner, the marble moves towards the point, and after some time tries to go outside of the screen, this is when the bounds checking comes into play and corrects the marble position so that the marble stays inside the screen. In this case the marble will never travel a distance of totLenToTravelSqrd, because of the correction is its position. So here we detect the end condition when there is not much change in marbles position. I use the value 4 in the second condition above. After experimenting with a few values, 4 seemed to work okay. There is a small thing missing in the code above. In the normal case, case 1, when the update method runs for the last time, marble position over shoots the destination point. This happens because the position is incremented in steps (which are not small enough), so in this case too, we should have corrected the marble position, so that the center point of the marble sits exactly on top of the destination point. I’ll add this later and update the post. This has been a pretty long post already, so I’ll leave you with a video of how this program looks while running. Notice in the video that the marble moves like a bot, without any grace what so ever. And that is because the speed of the marble is fixed at 6. In the next post we will see how to make the marble move a little more elegantly. And also, if Atan2(), Sine() and Cosine() are a little too much to digest, we’ll see how to achieve the same effect without using them, in the next to next post maybe. Ciao!

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