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• How is joystick axis information formatted from a USB Joystick?

  - by aquanar

  I actually just have a rather small question, but I have had the HARDEST time finding information about it. For the application I am programming for, there will be a 3-axis joystick being connected via USB to a Windows XP computer, and it is being handled by directx. That information will then be sent elsewhere to an embedded controller. I don't need to know too much of the intricacies of how directx handles it, but I want to know, how is the data for the axes formatted? Nearest I can tell, most joysticks nowadays have 12 bits of resolution, so is the data output as a 12-bit 2's compliment number? And after that, is it represented as a signed 16-bit integer when it is captured from directx? I'd like to know this so I know how I will work with the data at the embedded platform side, such as how to format the packets sending data to the embedded side, as well ashow to use the information once it is on the embedded side.

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• How i draw the graph including X- and Y-axis lines?

  - by Rajendra Bhole

  Hi, I want to make an application in which i want to make simple graph using NSObject class and using CGContext method. All lines should be displaying dynamically in X and Y-axis interval text also, i trying develop something like following code, CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextSetLineWidth(ctx, 2.0); //(number of lines) CGContextMoveToPoint(ctx, 30.0, 230.0); CGContextAddLineToPoint(ctx, 30.0, 440.0); //CGContextAddLineToPoint(ctx, 320.0, 420.0); //CGContextStrokePath(ctx); for(float x = 20.0; x <= 320.0; x++) { CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextMoveToPoint(ctx, x, 420.0); CGContextAddLineToPoint(ctx, x+45.0, 420.0); CGContextStrokePath(ctx); } How i develop using above functions? Thanks.

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• More information wanted on error: CREATE ASSEMBLY for assembly failed because assembly failed verif

  - by turnip.cyberveggie

  I have a small application that uses SQL Server 2005 Express with CLR stored procedures. It has been successfully installed and runs on many computers running XP and Vista. To create the assembly the following SQL is executed (names changed to protect the innocent): CREATE ASSEMBLY myAssemblyName FROM 'c:\pathtoAssembly\myAssembly.dll' On one computer (a test machine that reflects other computers targeted for installation) that is running Vista and has some very aggressive security policy restrictions I receive the following error: << Start Error Message Msg 6218, Level 16, State 2, Server domain\servername, Line 2 CREATE ASSEMBLY for assembly 'myAssembly' failed because assembly 'myAssembly' failed verification. Check if the referenced assemblies are up-to-date and trusted (for external_access or unsafe) to execute in the database. CLR Verifier error messages if any will follow this message [ : myProcSupport.Axis::Proc1][mdToken=0x6000004] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc2][mdToken=0x6000005] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc3][mdToken=0x6000006] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::.ctor][mdToken=0x600000a] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc4][mdToken=0x6000001] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc5][mdToken=0x6000002] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc6][mdToken=0x6000007] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc7][mdToken=0x6000008] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc8][mdToken=0x6000009] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc8][mdToken=0x600000b] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation. [ : myProcSupport.Axis::Proc9][mdToken=0x600000c] [HRESULT 0x8007000E] - Not enough storage is available to complete this operation.... << End Error Message The C# DLL is defined as “Safe” as it only uses data contained in the database. The DLL is not normally signed, but I provided a signed version to test and received the same results. The installation is being done by someone else, and I don’t have access to the box, but they are executing scripts that I provided and work on other computers. I have tried to find information about this error beyond what the results of the script provide, but I haven’t found anything helpful. The person executing the script to create the assembly is logged in with an Admin account, is running CMD as admin, is connecting to the DB via Windows Authentication, has been added to the dbo_owner role, and added to the server role SysAdmin with the hopes that it is a permissions issue. This hasn't changed anything. Do I need to configure SQL Server 2005 Express differently for this environment? Is this error logged anywhere other than just the output from SQLCMD? What could cause this error? Could Vista security policies cause this? I don’t have access to the computer (the customer is doing the testing) so I can’t examine the box myself. TIA

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• OpenGL-ES Texture Atlas. t axis is inverted.

  - by Feet

  I'm mapping a texture from my texture atlas to a square on a cube. For some reason, the t axis is inverted with 0 being at the top and 1 being at the bottom. Also, I have to specify the texture coordinates in clockwise order rather than counter-clockwise. I am using counter-clockwise windings. The vertices, indices and texture coordinates I'm using are below. float vertices[] = { // Front face -width, -height, depth, // 0 width, -height, depth, // 1 width, height, depth, // 2 -width, height, depth, // 3 // Back Face width, -height, -depth, // 4 -width, -height, -depth, // 5 -width, height, -depth, // 6 width, height, -depth, // 7 // Left face -width, -height, -depth, // 8 -width, -height, depth, // 9 -width, height, depth, // 10 -width, height, -depth, // 11 // Right face width, -height, depth, // 12 width, -height, -depth, // 13 width, height, -depth, // 14 width, height, depth, // 15 // Top face -width, height, depth, // 16 width, height, depth, // 17 width, height, -depth, // 18 -width, height, -depth, // 19 // Bottom face -width, -height, -depth, // 20 width, -height, -depth, // 21 width, -height, depth, // 22 -width, -height, depth, // 23 }; short indices[] = { // Front // Back 0,1,2, 0,2,3, 4,5,6, 4,6,7, // Left // Right 8,9,10, 8,10,11, 12,13,14, 12,14,15, // Top // Bottom 16,17,18, 16,18,19, 20,21,22, 20,22,23, }; float textures[] = { // Front 0.0f, 0.0f, 0.25f, 0.0f, 0.25f, 0.25f, 0.0f, 0.25f, // Back 0.25f, 0.0f, 0.50f, 0.0f, 0.50f, 0.25f, 0.25f, 0.25f, // Left 0.50f, 0.0f, 0.75f, 0.0f, 0.75f, 0.25f, 0.50f, 0.25f, // Right 0.75f, 0.0f, 1f, 0.0f, 1f, 0.25f, 0.75f, 0.25f, // Top 0.0f, 0.25f, 0.25f, 0.25f, 0.25f, 0.50f, 0.0f, 0.50f, // Bottom 0.25f, 0.25f, 0.50f, 0.25f, 0.50f, 0.50f, 0.25f, 0.50f, };

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• How to use XPath to filter elements by TextContent? get parent by axis?

  - by Michael Mao

  Hi all: I've found a similar question on SO, however, that seems not exactly what I wanna achieve: Say, this is a sample XML file: <root> <item> <id isInStock="true">10001</id> <category>Loose Balloon</category> </item> <item> <id isInStock="true">10001</id> <category>Bouquet Balloon</category> </item> <item> <id isInStock="true">10001</id> <category>Loose Balloon</category> </item> </root> If I wanna get a "filtered" subset of the item elements from this XML, how could I use an XPath expression to directly address that? XPathExpression expr = xpath.compile("/root/item/category/text()"); I now know this would evaluate to be the collection of all the TextContent from the categories, however, that means I have to use a collection to store the values, then iterate, then go back to grab other related info such as the item id again. Another question is : how could I refer to the parent node properly? Say, this xpath expression would get me the collection of all the id nodes, right? But what I want is the collection of item nodes: XPathExpression expr = xpath.compile("/root/item/id[@isInStock='true']"); I know I should use the "parent" axis to refer to that, but I just cannot make it right... Is there a better way of doing this sort of thing? Learning the w3cschools tutorials now... Sorry I am new to XPath in Java, and thanks a lot in advance.

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• Object disapear/don't scale in the Z-AXIS of OPENGL.

  - by user315684

  This code is susposed to have a QUAD orbit around a center point in basically a circle. The problem is while it does the X rotation fine it disapears when it moves in Z axis and doesn't appear to change in size. It feel like it's rendering everything in Orthagraphic view or something. This is my first OpenGL project. OPENGL CODE START HERE glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT); glMatrixMode (GL_PROJECTION); glPushMatrix(); //glRotatef(theta, 0.0f, 0.0f, 1.0f); glScalef(0.75f, 0.75f, 0.75f); glTranslatef(planeX, -0.0f, 0.0f); glBegin(GL_QUADS); glColor3f(1.0f, 0.0f, 0.0f); glVertex3f(0.0f, 0.0f, planeZ); glColor3f(0.0f, 1.0f, 0.0f); glVertex3f(0.0f, 1.0f, planeZ); glColor3f(0.0f, 0.0f, 1.0f); glVertex3f(1.0f, 1.0f, planeZ); glColor3f(0.0f, 0.0f, 1.0f); glVertex3f(1.0f, 0.0f, planeZ); glEnd(); glPopMatrix(); SwapBuffers(hDC); theta += 1.0f; planeX = (sin(0.0314159265f*theta)); planeZ = (cos(0.0314159265f*theta)); Sleep (1); ENDS HERE

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• Array of pointers in C++.

  - by Theorem

  I am not understanding the output of this , #include <iostream> using namespace std; // pointers and arrays char ch1 = 'a' , ch2= 'b'; char ch3[6] = {'c', 'd', 'e', 'f', 'g' , 'h'}; char *ptr[3]; int main () { ptr[0] = &ch1 ; ptr[2] = ch3; cout << &ch1 << endl; } The out put is abcdefgh . isn't &ch1 supposed to give the address of ch1 ? I cannot make sense why the output should be abcdefgh.

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• PHP mtChart (new pChart): how do i control the angle of x-axis labels?

  - by gsquare567

  i am trying to graph the results of a survey, where the question is multiple choice. eg. How would you describe this website? format: option | number of times selected | percentage of users who selected that option Informative 1 50% All of the above 1 50% Interesting 0 0% Intelligent 0 0% Cool 0 0% Incredible 0 0% Sleek 0 0% Amazing the graph is a bar graph, where each bar represents one of those options, and the height of the bar depends on the number of times selected. however, the labels are slanted at a 45 degree angle and are barely readable! here is my code: <?php require_once ("includes/common.php"); require_once ("graph/mtChart.min.php"); // type must be specified $type = $_GET['type']; if($type == "surveys_report_MC_or_CB") { // PARAMS $surveyID = $_GET['surveyID']; $questionID = $_GET['questionID']; // END PARAMS $question = SurveyQuestions::getSingle($questionID); $answers = SurveyAnswers::getAll($questionID); $options = SurveyQuestionOptions::getAll($question[SurveyQuestions::surveyQuestionID]); $others = SurveyAnswers::setOptionCounts($options, $answers); $printedOthers = false; // set graph $values = array(); $axisLabels = array(); foreach($options as $option) { $values[$option[SurveyQuestionOptions::optionText]] = $option['count']; $axisLabels[] = $option[SurveyQuestionOptions::optionText]; } $graphs = array(); $graphs[0] = $values; $xName = "Option"; $yName = "Number of Times Selected"; $graphTitle = $question[SurveyQuestions::question]; $series = array("Total"); $showLegend = false; $tall = false; } drawGraph($graphs, $axisLabels, $xName, $yName, $graphTitle, $series, $showLegend, $tall); function drawGraph($graphs, $axisLabels, $xName, $yName, $graphTitle, $series, $showLegend, $tall) { $Graph = ($tall) ? new mtChart(575,375) : new mtChart(575,275); // Dataset definition $avg = 0; $i = 0; foreach ($graphs as $key => $value) { $Graph->AddPoint($value,"series" . $key); $Graph->SetSerieName($series[$key],"series" . $key); // Get average $avg += array_sum($value); $size = sizeof($value); $i += $size; // Calculate x-axis tick interval $step = ceil($size / 25); } $Graph->AddPoint($axisLabels,"XLabel"); $Graph->AddAllSeries(); $Graph->RemoveSerie("XLabel"); $Graph->SetAbsciseLabelSerie("XLabel"); $Graph->SetXAxisName($xName); $Graph->SetYAxisName($yName); // Get from cache if it exists $Graph->enableCaching(NULL, 'graph/cache/'); $Graph->GetFromCache(); // Initialize the graph $Graph->setInterval($step); $Graph->setFontProperties("graph/tahoma.ttf",8); ($showLegend) ? $Graph->setGraphArea(45,30,475,200) : $Graph->setGraphArea(75,30,505,200); $Graph->drawGraphArea(255,255,255,TRUE); $Graph->drawScale(SCALE_START0,100,100,100,TRUE,55,1,TRUE); $Graph->drawGrid(4,TRUE,230,230,230,50); // Draw the 0 line $Graph->setFontProperties("graph/tahoma.ttf",6); $Graph->drawTreshold(0,143,55,72,TRUE,TRUE); // Draw the bar graph $Graph->drawBarGraph(); // Draw average line $Graph->drawTreshold($avg/$i, 0, 0, 0, FALSE, FALSE, 5); // Finish the graph $Graph->setFontProperties("graph/tahoma.ttf",8); if ($showLegend) { $Graph->drawLegend(482,30,255,255,255,255,255,255,100,100,100); } $Graph->setFontProperties("graph/tahoma.ttf",10); $Graph->drawTitle(0,22,$graphTitle,100,100,100,555); // Draw Graph $Graph->Stroke(); } and here is where i use it on the page: <div class="graph_container"> <img src="drawGraph.php?type=surveys_report_MC_or_CB&surveyID=<?php echo $survey[Surveys::surveyID] ?>&questionID=<?php echo $question[SurveyQuestions::surveyQuestionID] ?>" /> is there a setting i can apply to the graph which will make the text look nicer, or at least let me set the angle to 90 degrees so people can read it if they cock their head to the left? thanks! btw, mtchart is located here: http://code.google.com/p/mtchart/ and pchart (the original, which has mainly the same code) is here: http://pchart.sourceforge.net/documentation.php

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• How can I use a delimiter in wmic output, separating columns?

  - by Abhishek Simon

  I want to fetch Windows Hotfix listing with some format, whose output can be separated with some delimiter. so far I found a wmic command which gives me a desired output but the problem is the \s delimiter is not going to work here. Is there a way I can place some , or anyother character, which I can later use in java program to get individual columns? Command wmic qfe get caption,csname,description,hotfixid,installedby,installedon Output Caption CSName Description HotFixID InstalledBy InstalledOn http://go.microsoft.com/fwlink/?LinkId=161784 Abhishek Update KB971033 NT AUTHORITY\SYSTEM 3/15/2012 http://support.microsoft.com/?kbid=2032276 Abhishek Security Update KB2032276 NT AUTHORITY\SYSTEM 3/15/2012 .. . Update I am trying for /f "tokens=1,2,3,4,5,6,7,8,9,10,11" %g in ('wmic qfe get caption,csname,description,fixcomments,hotfixid,installdate,installedby,installedon,name,servicepackineffect,status') do @echo %g,%h,%i,%j,%k,%l,%m,%n,%o,%p but it gives me invalid GET Expression C:\Users\Abhishek\Desktop>for /f "tokens=1,2,3,4,5,6,7,8,9,10,11" %g in ('wmic qfe get caption,csname,description,fixcomments,hotfixid,installdate,installedby,installedon,name,servicepackineffect,status') do @echo %g,%h,%i,%j,%k,%l,%m,%n,%o,%p Invalid GET Expression. What is the problem here? This might solve the problem for me . More Update I even tried the below command but this too does not solve space problem Command for /f "tokens=1,2,3,4,5,6,7,8,9,10,11" %g in ('wmic qfe list') do @echo %g,%h,%i,%j,%k,%l,%m,%n,%o,%p Output Caption,CSName,Description,FixComments,HotFixID,InstallDate,InstalledBy,InstalledOn,Name,ServicePackInEffect http://go.microsoft.com/fwlink/?LinkId=161784,Abhishek,Update,KB971033,NT,AUTHOR,,Y\SYSTEM,3/15/2012, http://support.microsoft.com/?kbid=2281679,Abhishek,Security,Update,KB2281679,NT,AUTHORITY\SYSTEM,3/15/2012, http://support.microsoft.com/?kbid=2284742,Abhishek,Update,KB2284742,NT,AUTHORIT,,SYSTEM,3/15/2012, http://support.microsoft.com/?kbid=2286198,Abhishek,Security,Update,KB2286198,NT,AUTHORITY\SYSTEM,3/15/2012,

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• Sorting manually generated index using perl script

  - by Pradeep Singh

  \item Bernoulli measure, 14 \item cellular automata \subitem Soft, 3, 28 \subitem balance theorem, 23, 45 \item tiles \subitem tiling problem, 19, 58 \subitem aperiodic tile set, 18, 45 \item Garden-of-Eden -theorem, 12 \item Bernoulli measure, 15, 16, 35 \item cellular automata \subitem balance theorem, 9, 11, 14 \subitem blocking word, 22, 32 \item Garden-of-Eden -theorem, 32 I have to sort the above index alphabetically using a perl script. Duplicate item or subitem entries should be merged and their numbers should be sorted. The subitems also should be sorted under respective item and their numbers should be also sorted. If same item is repeated in more than one place with subitems all the subitems should be merged under a single item and also subitems should be sorted

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• Problem separating C++ code in header, inline functions and code.

  - by YuppieNetworking

  Hello all, I have the simplest code that I want to separate in three files: Header file: class and struct declarations. No implementations at all. Inline functions file: implementation of inline methods in header. Code file: normal C++ code for more complicated implementations. When I was about to implement an operator[] method, I couldn't manage to compile it. Here is a minimal example that shows the same problem: Header (myclass.h): #ifndef _MYCLASS_H_ #define _MYCLASS_H_ class MyClass { public: MyClass(const int n); virtual ~MyClass(); double& operator[](const int i); double operator[](const int i) const; void someBigMethod(); private: double* arr; }; #endif /* _MYCLASS_H_ */ Inline functions (myclass-inl.h): #include "myclass.h" inline double& MyClass::operator[](const int i) { return arr[i]; } inline double MyClass::operator[](const int i) const { return arr[i]; } Code (myclass.cpp): #include "myclass.h" #include "myclass-inl.h" #include <iostream> inline MyClass::MyClass(const int n) { arr = new double[n]; } inline MyClass::~MyClass() { delete[] arr; } void MyClass::someBigMethod() { std::cout << "Hello big method that is not inlined" << std::endl; } And finally, a main to test it all: #include "myclass.h" #include <iostream> using namespace std; int main(int argc, char *argv[]) { MyClass m(123); double x = m[1]; m[1] = 1234; cout << "m[1]=" << m[1] << endl; x = x + 1; return 0; } void nothing() { cout << "hello world" << endl; } When I compile it, it says: main.cpp:(.text+0x1b): undefined reference to 'MyClass::MyClass(int)' main.cpp:(.text+0x2f): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x49): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x65): undefined reference to 'MyClass::operator[](int)' However, when I move the main method to the MyClass.cpp file, it works. Could you guys help me spot the problem? Thank you.

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• Separating code logic from the actual data structures. Best practices?

  - by Patrick

  I have an application that loads lots of data into memory (this is because it needs to perform some mathematical simulation on big data sets). This data comes from several database tables, that all refer to each other. The consistency rules on the data are rather complex, and looking up all the relevant data requires quite some hashes and other additional data structures on the data. Problem is that this data may also be changed interactively by the user in a dialog. When the user presses the OK button, I want to perform all the checks to see that he didn't introduce inconsistencies in the data. In practice all the data needs to be checked at once, so I cannot update my data set incrementally and perform the checks one by one. However, all the checking code work on the actual data set loaded in memory, and use the hashing and other data structures. This means I have to do the following: Take the user's changes from the dialog Apply them to the big data set Perform the checks on the big data set Undo all the changes if the checks fail I don't like this solution since other threads are also continuously using the data set, and I don't want to halt them while performing the checks. Also, the undo means that the old situation needs to be put aside, which is also not possible. An alternative is to separate the checking code from the data set (and let it work on explicitly given data, e.g. coming from the dialog) but this means that the checking code cannot use hashing and other additional data structures, because they only work on the big data set, making the checks much slower. What is a good practice to check user's changes on complex data before applying them to the 'application's' data set?

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• Correct Display configuration. Errors while trying to arrange displays

  - by David Russell Parrish Bojrquez

  I am trying to set up my tv with my laptop trough a VGA cable. The display application in Ubuntu throws a lot of errors to me and I have given up in trying to do it myself. I try to apply the 1920 1080 display. The selected configuration for displays could not be applied Requested size (3200, 1080) exceeds 3D hardware limit (2048, 2048). You must either rearrange the displays so that they fit within a (2048, 2048) square or select the Ubuntu 2D session at login. And Also this: Failed to apply configuration: %s GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._gnome_2drr_2derror_2dquark.Code3: Requested size (3200, 1080) exceeds 3D hardware limit (2048, 2048). You must either rearrange the displays so that they fit within a (2048, 2048) square or select the Ubuntu 2D session at login. Please Help. @Leozitop No I don't see anything when connected to 1920 1080 because the setup fails before actually applying. Yes there are other resolutions which do work. I believe the problem has something to do with the rotation it is set up. My Ubuntu Display application has only clockwise and counterclockwise options for the TV display. I really don't know why this is happening. Basic procedure: Plug in cable, did not get the resolution I wanted. Changed settings, applied them. Re-peat until desired display is shown. I'm not a computer illiterate, really it baffles me that this is happening. Output of xrandr: david@LapUbuntu:~$ xrandr Screen 0: minimum 320 x 200, current 1880 x 800, maximum 4096 x 4096 LVDS1 connected 1280x800+0+0 (normal left inverted right x axis y axis) 331mm x 207mm 1280x800 60.0*+ 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 connected 600x800+1280+0 left (normal left inverted right x axis y axis) 1600mm x 900mm 1920x1080 60.0 + 1280x1024 60.0 1360x768 60.0 1280x720 60.0 1024x768 60.0 800x600 60.3* 640x480 60.0 TV1 unknown connection (normal left inverted right x axis y axis) 848x480 59.9 + 640x480 59.9 + 1024x768 59.9 800x600 59.9 Note that VGA says left and indeed it is, but no other option was available in the display. Also, note the TV1 unknown connection which I have no idea what it is. Note, also, that this has nothing to do with the display since W7 on the computer works fine and since while boot up, and also, before starting session in ubuntu the rotation is normal. I'll also mention that I HAVE re-installed Ubuntu since I had posted this question from a Live CD of 12.04 LTS. And that before the posting of the question also using 12.04 before another backup that I had to do, the VGA setup was fine without any problems.

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• How can we view 3d objects from top down view in TD game

  - by Syed

  I am making a tower defense game. I am working in x and y axis only. I have made a grid, snapped towers and made a pathfinding algo to run enemy. Initially I have worked with cubes and spheres in place of towers and enemies. Now I am going to place real towers (3D). Note that I haven't used z axis up till now. The user will analyze the game from top down view. I want the user to see towers placement with a little bit of 3d view but I have made my all code in 2d thing. Is there any solution to my problem that somewhat tower placement would view a 3D touch or you can say 2.5D ?? (like fieldrunners) or should I have to involve z axis and ignoring y axis ?

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• Ball bouncing at a certain angle and efficiency computations

  - by X Y

  I would like to make a pong game with a small twist (for now). Every time the ball bounces off one of the paddles i want it to be under a certain angle (between a min and a max). I simply can't wrap my head around how to actually do it (i have some thoughts and such but i simply cannot implement them properly - i feel i'm overcomplicating things). Here's an image with a small explanation . One other problem would be that the conditions for bouncing have to be different for every edge. For example, in the picture, on the two small horizontal edges i do not want a perfectly vertical bounce when in the middle of the edge but rather a constant angle (pi/4 maybe) in either direction depending on the collision point (before the middle of the edge, or after). All of my collisions are done with the Separating Axes Theorem (and seem to work fine). I'm looking for something efficient because i want to add a lot of things later on (maybe polygons with many edges and such). So i need to keep to a minimum the amount of checking done every frame. The collision algorithm begins testing whenever the bounding boxes of the paddle and the ball intersect. Is there something better to test for possible collisions every frame? (more efficient in the long run,with many more objects etc, not necessarily easy to code). I'm going to post the code for my game: Paddle Class public class Paddle : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private bool keybEnabled; private bool isLeftPaddle; private Texture2D paddleSprite; private Vector2 paddlePosition; private float paddleSpeedY; private Vector2 paddleScale = new Vector2(1f, 1f); private const float DEFAULT_Y_SPEED = 150; private Vector2[] Normals2Edges; private Vector2[] Vertices = new Vector2[4]; private List<Vector2> lst = new List<Vector2>(); private Vector2 Edge; #endregion #region Properties public float Speed { get {return paddleSpeedY; } set { paddleSpeedY = value; } } public Vector2[] Normal2EdgesVector { get { NormalsToEdges(this.isLeftPaddle); return Normals2Edges; } } public Vector2[] VertexVector { get { return Vertices; } } public Vector2 Scale { get { return paddleScale; } set { paddleScale = value; NormalsToEdges(this.isLeftPaddle); } } public float X { get { return paddlePosition.X; } set { paddlePosition.X = value; } } public float Y { get { return paddlePosition.Y; } set { paddlePosition.Y = value; } } public float Width { get { return (Scale.X == 1f ? (float)paddleSprite.Width : paddleSprite.Width * Scale.X); } } public float Height { get { return ( Scale.Y==1f ? (float)paddleSprite.Height : paddleSprite.Height*Scale.Y ); } } public Texture2D GetSprite { get { return paddleSprite; } } public Rectangle Boundary { get { return new Rectangle((int)paddlePosition.X, (int)paddlePosition.Y, (int)this.Width, (int)this.Height); } } public bool KeyboardEnabled { get { return keybEnabled; } } #endregion private void NormalsToEdges(bool isLeftPaddle) { Normals2Edges = null; Edge = Vector2.Zero; lst.Clear(); for (int i = 0; i < Vertices.Length; i++) { Edge = Vertices[i + 1 == Vertices.Length ? 0 : i + 1] - Vertices[i]; if (Edge != Vector2.Zero) { Edge.Normalize(); //outer normal to edge !! (origin in top-left) lst.Add(new Vector2(Edge.Y, -Edge.X)); } } Normals2Edges = lst.ToArray(); } public float[] ProjectPaddle(Vector2 axis) { if (Vertices.Length == 0 || axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, Vertices[0]); max = min; for (int i = 1; i < Vertices.Length; i++) { float p = Vector2.Dot(axis, Vertices[i]); if (p < min) min = p; else if (p > max) max = p; } return (new float[2] { min, max }); } public Paddle(Game game, bool isLeftPaddle, bool enableKeyboard = true) : base(game) { contentManager = new ContentManager(game.Services); keybEnabled = enableKeyboard; this.isLeftPaddle = isLeftPaddle; } public void setPosition(Vector2 newPos) { X = newPos.X; Y = newPos.Y; } public override void Initialize() { base.Initialize(); this.Speed = DEFAULT_Y_SPEED; X = 0; Y = 0; NormalsToEdges(this.isLeftPaddle); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleSprite = contentManager.Load<Texture2D>(@"Content\pongBar"); } public override void Update(GameTime gameTime) { //vertices array Vertices[0] = this.paddlePosition; Vertices[1] = this.paddlePosition + new Vector2(this.Width, 0); Vertices[2] = this.paddlePosition + new Vector2(this.Width, this.Height); Vertices[3] = this.paddlePosition + new Vector2(0, this.Height); // Move paddle, but don't allow movement off the screen if (KeyboardEnabled) { float moveDistance = Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState newKeyState = Keyboard.GetState(); if (newKeyState.IsKeyDown(Keys.Down) && Y + paddleSprite.Height + moveDistance <= Game.GraphicsDevice.Viewport.Height) { Y += moveDistance; } else if (newKeyState.IsKeyDown(Keys.Up) && Y - moveDistance >= 0) { Y -= moveDistance; } } else { if (this.Y + this.Height > this.GraphicsDevice.Viewport.Height) { this.Y = this.Game.GraphicsDevice.Viewport.Height - this.Height - 1; } } base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(SpriteSortMode.Texture,null); spriteBatch.Draw(paddleSprite, paddlePosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Ball Class public class Ball : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private const float DEFAULT_SPEED = 50; private float speedIncrement = 0; private Vector2 ballScale = new Vector2(1f, 1f); private const float INCREASE_SPEED = 50; private Texture2D ballSprite; //initial texture private Vector2 ballPosition; //position private Vector2 centerOfBall; //center coords private Vector2 ballSpeed = new Vector2(DEFAULT_SPEED, DEFAULT_SPEED); //speed #endregion #region Properties public float DEFAULTSPEED { get { return DEFAULT_SPEED; } } public Vector2 ballCenter { get { return centerOfBall; } } public Vector2 Scale { get { return ballScale; } set { ballScale = value; } } public float SpeedX { get { return ballSpeed.X; } set { ballSpeed.X = value; } } public float SpeedY { get { return ballSpeed.Y; } set { ballSpeed.Y = value; } } public float X { get { return ballPosition.X; } set { ballPosition.X = value; } } public float Y { get { return ballPosition.Y; } set { ballPosition.Y = value; } } public Texture2D GetSprite { get { return ballSprite; } } public float Width { get { return (Scale.X == 1f ? (float)ballSprite.Width : ballSprite.Width * Scale.X); } } public float Height { get { return (Scale.Y == 1f ? (float)ballSprite.Height : ballSprite.Height * Scale.Y); } } public float SpeedIncreaseIncrement { get { return speedIncrement; } set { speedIncrement = value; } } public Rectangle Boundary { get { return new Rectangle((int)ballPosition.X, (int)ballPosition.Y, (int)this.Width, (int)this.Height); } } #endregion public Ball(Game game) : base(game) { contentManager = new ContentManager(game.Services); } public void Reset() { ballSpeed.X = DEFAULT_SPEED; ballSpeed.Y = DEFAULT_SPEED; ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } public void SpeedUp() { if (ballSpeed.Y < 0) ballSpeed.Y -= (INCREASE_SPEED + speedIncrement); else ballSpeed.Y += (INCREASE_SPEED + speedIncrement); if (ballSpeed.X < 0) ballSpeed.X -= (INCREASE_SPEED + speedIncrement); else ballSpeed.X += (INCREASE_SPEED + speedIncrement); } public float[] ProjectBall(Vector2 axis) { if (axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, this.ballCenter) - this.Width/2; //center - radius max = min + this.Width; //center + radius return (new float[2] { min, max }); } public void ChangeHorzDirection() { ballSpeed.X *= -1; } public void ChangeVertDirection() { ballSpeed.Y *= -1; } public override void Initialize() { base.Initialize(); ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); ballSprite = contentManager.Load<Texture2D>(@"Content\ball"); } public override void Update(GameTime gameTime) { if (this.Y < 1 || this.Y > GraphicsDevice.Viewport.Height - this.Height - 1) this.ChangeVertDirection(); centerOfBall = new Vector2(ballPosition.X + this.Width / 2, ballPosition.Y + this.Height / 2); base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.Draw(ballSprite, ballPosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Main game class public class gameStart : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; public gameStart() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; this.Window.Title = "Pong game"; } protected override void Initialize() { ball = new Ball(this); paddleLeft = new Paddle(this,true,false); paddleRight = new Paddle(this,false,true); Components.Add(ball); Components.Add(paddleLeft); Components.Add(paddleRight); this.Window.AllowUserResizing = false; this.IsMouseVisible = true; this.IsFixedTimeStep = false; this.isColliding = false; base.Initialize(); } #region MyPrivateStuff private Ball ball; private Paddle paddleLeft, paddleRight; private int[] bit = { -1, 1 }; private Random rnd = new Random(); private int updates = 0; enum nrPaddle { None, Left, Right }; private nrPaddle PongBar = nrPaddle.None; private ArrayList Axes = new ArrayList(); private Vector2 MTV; //minimum translation vector private bool isColliding; private float overlap; //smallest distance after projections private Vector2 overlapAxis; //axis of overlap #endregion protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleLeft.setPosition(new Vector2(0, this.GraphicsDevice.Viewport.Height / 2 - paddleLeft.Height / 2)); paddleRight.setPosition(new Vector2(this.GraphicsDevice.Viewport.Width - paddleRight.Width, this.GraphicsDevice.Viewport.Height / 2 - paddleRight.Height / 2)); paddleLeft.Scale = new Vector2(1f, 2f); //scale left paddle } private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] <= circle[0] || circle[1] <= pad[0]) { return false; } if (pad[1] - circle[0] < circle[1] - pad[0]) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax; } } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * overlap; } return true; } protected override void Update(GameTime gameTime) { updates += 1; float ftime = 5 * (float)gameTime.ElapsedGameTime.TotalSeconds; if (updates == 1) { isColliding = false; int Xrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; int Yrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; ball.SpeedX = Xrnd * ball.SpeedX; ball.SpeedY = Yrnd * ball.SpeedY; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } else { updates = 100; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } //autorun :) paddleLeft.Y = ball.Y; //collision detection PongBar = nrPaddle.None; if (ball.Boundary.Intersects(paddleLeft.Boundary)) { PongBar = nrPaddle.Left; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleLeft.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleLeft.VertexVector, ball.ballCenter)); } } else if (ball.Boundary.Intersects(paddleRight.Boundary)) { PongBar = nrPaddle.Right; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleRight.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleRight.VertexVector, ball.ballCenter)); } } if (PongBar != nrPaddle.None && !isColliding) switch (PongBar) { case nrPaddle.Left: if (ShapesIntersect(paddleLeft, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; case nrPaddle.Right: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; default: break; } if (!ShapesIntersect(paddleRight, ball) && !ShapesIntersect(paddleLeft, ball)) isColliding = false; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; //check ball movement if (ball.X > paddleRight.X + paddleRight.Width + 2) { //IncreaseScore(Left); ball.Reset(); updates = 0; return; } else if (ball.X < paddleLeft.X - 2) { //IncreaseScore(Right); ball.Reset(); updates = 0; return; } base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Aquamarine); spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend); spriteBatch.End(); base.Draw(gameTime); } } And one method i've used: public static Vector2 NormAxisFromCircle2ClosestVertex(Vector2[] vertices, Vector2 circle) { Vector2 temp = Vector2.Zero; if (vertices.Length > 0) { float dist = (circle.X - vertices[0].X) * (circle.X - vertices[0].X) + (circle.Y - vertices[0].Y) * (circle.Y - vertices[0].Y); for (int i = 1; i < vertices.Length;i++) { if (dist > (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y)) { temp = vertices[i]; //memorize the closest vertex dist = (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y); } } temp = circle - temp; temp.Normalize(); } return temp; } Thanks in advance for any tips on the 4 issues. EDIT1: Something isn't working properly. The collision axis doesn't come out right and the interpolation also seems to have no effect. I've changed the code a bit: private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] < circle[0] || circle[1] < pad[0]) { return false; } if (Math.Abs(pad[1] - circle[0]) < Math.Abs(circle[1] - pad[0])) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax * (-1); } //to get the proper axis } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * Math.Abs(overlap); } return true; } And part of the Update method: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) { ball.X += MTV.X; ball.Y += MTV.Y; } //test if (overlapAxis.X == 0) //collision with horizontal edge { } else if (overlapAxis.Y == 0) //collision with vertical edge { float factor = Math.Abs(ball.ballCenter.Y - paddleRight.Y) / paddleRight.Height; if (factor > 1) factor = 1f; if (overlapAxis.X < 0) //left edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(-1, -3), new Vector2(-1, 3), factor)))); else //right edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(1, -3), new Vector2(1, 3), factor)))); } else //vertex collision??? { ball.Speed = -ball.Speed; } } What seems to happen is that "overlapAxis" doesn't always return the right one. So instead of (-1,0) i get the (1,0) (this happened even before i multiplied with -1 there). Sometimes there isn't even a collision registered even though the ball passes through the paddle... The interpolation also seems to have no effect as the angles barely change (or the overlapAxis is almost never (-1,0) or (1,0) but something like (0.9783473, 0.02743843)... ). What am i missing here? :(

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• Quaternion Camera Orbiting around a Sphere

  - by jessejuicer

  Background: I'm trying to create a game where the camera is always rotating around a single sphere. I'm using the DirectX D3DX math functions in C++ on Windows. The Problem: I cannot get both the camera position and orientation both working properly at the same time. Either one works but not both together. Here's the code for my quaternion camera that revolves around a sphere, always looking at the centerpoint of the sphere, ... as far as I understand it (but which isn't working properly): (I'm only going to present rotation around the X axis here, to simplify this post) Whenever the UP key is pressed or held down, the camera should rotate around the X axis, while looking at the centerpoint of the sphere (which is at 0,0,0 in the world). So, I build a quaternion that represents a small angle of rotation around the x axis like this (where 'deltaAngle' is a small enough number for a slow rotation): D3DXVECTOR3 rotAxis; D3DXQUATERNION tempQuat; tempQuat.x = 0.0f; tempQuat.y = 0.0f; tempQuat.z = 0.0f; tempQuat.w = 1.0f; rotAxis.x = 1.0f; rotAxis.y = 0.0f; rotAxis.z = 0.0f; D3DXQuaternionRotationAxis(&tempQuat, &rotAxis, deltaAngle); ...and I accumulate the result into the camera's current orientation quat, like this: D3DXQuaternionMultiply(&cameraOrientationQuat, &cameraOrientationQuat, &tempQuat); ...which all works fine. Now I need to build a view matrix to pass to DirectX SetTransform function. So I build a rotation matrix from the camera orientation quat as follows: D3DXMATRIXA16 rotationMatrix; D3DXMatrixIdentity(&rotationMatrix); D3DXMatrixRotationQuaternion(&rotationMatrix, &cameraOrientationQuat); ...Now (as seen below) if I just transpose that rotationMatrix and plug it into the 3x3 section of the view matrix, then negate the camera's position and plug it into the translation section of the view matrix, the rotation magically works. Perfectly. (even when I add in rotations for all three axes). There's no gimbal lock, just a smooth rotation all around in any direction. BUT- this works even though I never change the camera's position. At all. Which sorta blows my mind. I even display the camera position and can watch it stay constant at it's starting point (0.0, 0.0, -4000.0). It never moves, but the rotation around the sphere is perfect. I don't understand that. For proper view rotation, the camera position should be revolving around the sphere. Here's the rest of building the view matrix (I'll talk about the commented code below). Note that the camera starts out at (0.0, 0.0, -4000.0) and m_camDistToTarget is 4000.0: /* D3DXVECTOR3 vec1; D3DXVECTOR4 vec2; vec1.x = 0.0f; vec1.y = 0.0f; vec1.z = -1.0f; D3DXVec3Transform(&vec2, &vec1, &rotationMatrix); g_cameraActor->pos.x = vec2.x * g_cameraActor->m_camDistToTarget; g_cameraActor->pos.y = vec2.y * g_cameraActor->m_camDistToTarget; g_cameraActor->pos.z = vec2.z * g_cameraActor->m_camDistToTarget; */ D3DXMatrixTranspose(&g_viewMatrix, &rotationMatrix); g_viewMatrix._41 = -g_cameraActor->pos.x; g_viewMatrix._42 = -g_cameraActor->pos.y; g_viewMatrix._43 = -g_cameraActor->pos.z; g_viewMatrix._44 = 1.0f; g_direct3DDevice9->SetTransform( D3DTS_VIEW, &g_viewMatrix ); ...(The world matrix is always an identity, and the perspective projection works fine). ...So, without the commented code being compiled, the rotation works fine. But to be proper, for obvious reasons, the camera position should be rotating around the sphere, which it currently is not. That's what the commented code is supposed to do. And when I add in that chunk of code to do that, and look at all the data as I hold the keys down (using UP, DOWN, LEFT, RIGHT to rotate different directions) all the values look correct! The camera position is rotating around the sphere just fine, and I can watch that happen visually too. The problem is that the camera orientation does not lookat the center of the sphere. It always looks straight forward down the z axis (toward positive z) as it revolves around the sphere. Yet the values of both the rotation matrix and the view matrix seem to be behaving correctly. (The view matrix orientation is the same as the rotation matrix, just transposed). For instance if I just hold down the key to spin around the x axis, I can watch the values of the three axes represented in the view matrix (x, y, and z axes)... view x-axis stays at (1.0, 0.0, 0.0), and view y-axis and z-axis both spin around the x axis just fine. All the numbers are changing as they should be... well, almost. As far as I can tell, the position of the view matrix is spinning around the sphere one direction (like clockwise), and the orientation (the axes in the view matrix) are spinning the opposite direction (like counter-clockwise). Which I guess explains why the orientation appears to stay straight ahead. I know the position is correct. It revolves properly. It's the orientation that's wrong. Can anyone see what am I doing wrong? Am I using these functions incorrectly? Or is my algorithm flawed? As usual I've been combing my code for simple mistakes for many hours. I'm willing to post the actual code, and a video of the behavior, but that will take much more effort. Thought I'd ask this way first.

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• What's wrong with this turn to face algorithm?

  - by Chan

  I implement a torpedo object that chases a rotating planet. Specifically, it will turn toward the planet each update. Initially my implement was: void move() { vector3<float> to_target = target - get_position(); to_target.normalize(); position += (to_target * speed); } which works perfectly for torpedo that is a solid sphere. Now my torpedo is actually a model, which has a forward vector, so using this method looks odd because it doesn't actually turn toward but jump toward. So I revised it a bit to get, double get_rotation_angle(vector3<float> u, vector3<float> v) const { u.normalize(); v.normalize(); double cosine_theta = u.dot(v); // domain of arccosine is [-1, 1] if (cosine_theta > 1) { cosine_theta = 1; } if (cosine_theta < -1) { cosine_theta = -1; } return math3d::to_degree(acos(cosine_theta)); } vector3<float> get_rotation_axis(vector3<float> u, vector3<float> v) const { u.normalize(); v.normalize(); // fix linear case if (u == v || u == -v) { v[0] += 0.05; v[1] += 0.0; v[2] += 0.05; v.normalize(); } vector3<float> axis = u.cross(v); return axis.normal(); } void turn_to_face() { vector3<float> to_target = (target - position); vector3<float> axis = get_rotation_axis(get_forward(), to_target); double angle = get_rotation_angle(get_forward(), to_target); double distance = math3d::distance(position, target); gl_matrix_mode(GL_MODELVIEW); gl_push_matrix(); { gl_load_identity(); gl_translate_f(position.get_x(), position.get_y(), position.get_z()); gl_rotate_f(angle, axis.get_x(), axis.get_y(), axis.get_z()); gl_get_float_v(GL_MODELVIEW_MATRIX, OM); } gl_pop_matrix(); move(); } void move() { vector3<float> to_target = target - get_position(); to_target.normalize(); position += (get_forward() * speed); } The logic is simple, I find the rotation axis by cross product, the angle to rotate by dot product, then turn toward the target position each update. Unfortunately, it looks extremely odds since the rotation happens too fast that it always turns back and forth. The forward vector for torpedo is from the ModelView matrix, the third column A: MODELVIEW MATRIX -------------------------------------------------- R U A T -------------------------------------------------- 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 -------------------------------------------------- Any suggestion or idea would be greatly appreciated.

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• Games display across both monitors when opened

  - by Mitch

  I am not sure what setting to change for this but I open games like Dungeon Crawl or a Steam game and the game wants to take up both screens. Is there a way to have the game open just on one screen xrandr shows this. So they are both on Screen 0: Screen 0: minimum 320 x 200, current 2966 x 900, maximum 8192 x 8192 LVDS1 connected 1366x768+1600+75 (normal left inverted right x axis y axis) 344mm x 193mm VGA1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 443mm x 249mm If you need any more info or can point me to a place you may have already found an answer please let me know.

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• xrandr shows VGA1 as disconnected

  - by Felix

  I have a Thinkpad W520 with Nvidia Optimus graphics. I have disabled the Nvidia card in BIOS (by selecting "integrated graphics"), so I'm running only on the integrated Intel graphics. I get full 3D acceleration, which would suggest the drivers are properly installed. However, I'm not able to use an external monitor. With the external monitor connected and turned on, running xrandr always gives: $ xrandr Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 LVDS1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm 1920x1080 60.0*+ 59.9 50.0 1680x1050 60.0 59.9 1600x1024 60.2 1400x1050 60.0 1280x1024 60.0 1440x900 59.9 1280x960 60.0 1360x768 59.8 60.0 1152x864 60.0 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 disconnected (normal left inverted right x axis y axis) What gives? It sees the VGA1 port (to which the external display is connected), but it appears disconnected. I have tried forcing a resolution as per these instructions, but when I do that X becomes unresponsive and I have to Ctrl-Alt-F1 and restart it.

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• How can I make Excel correlate data from two data sets into a single graph?

  - by Tom Ritter

  I have two datasets, one being sparser than the other. They look like this: Data Set 1: 4 50 5 55 6 60 7 70 8 80 Data Set 2: 4 10 6 20 8 30 I have several hundred points instead of this few. I want them in the same graph, the X axis being 4-8, the y axis being 0-100ish, and two lines, one for each data set. What I get is two lines, not correlated at all along the X axis, and the X axis being labeled from one of the two datasets, with the labels being wrong for the other. The smaller data set is one-point-per-tick on the x axis, when I need it to skip ticks and actually line up with the other data set. Not married to excel, willing to try this in something else if it's free.

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• How do I create weapon attachments?

  - by Tron86

  My question is; I am developing a game for XNA and I am trying to create a weapon attachment for my player model. My player model loads the .md3 format and reads tags for attachment points. I am able to get the tag of my model's hand. And I am also able to get the tag of my weapon's handle. Each tag I am able to get the rotation and position of and this is how I am calculating it: Model.worldMatrix = Matrix.CreateScale(Model.scale) * Matrix.CreateRotationX(-MathHelper.PiOver2) * Matrix.CreateRotationY(MathHelper.PiOver2); Pretty simple, the player model has a scale and its orientation(it loads on its side so I just use a 90 degree X axis rotation, and a Y axis rotation to face away from the camera). I then calculate the torso tag on the lower body, which gives me a local coordinate at the waist. Then I take that matrix and calculate the tag_weapon in the upper body. This gives me the hand position in local space. I also get the rotation matrix from that tag that I store for later use. All this seems to work fine. Now I move onto my weapon: Matrix weaponWorld = Matrix.CreateScale(CurrentWeapon.scale) * Matrix.CreateRotationX(-MathHelper.PiOver2) * TagRotationMatrix * Matrix.CreateTranslation(HandTag.Position) * Matrix.CreateRotationY(PlayerRotation) * Matrix.CreateTranslation(CollisionBody.Position) * You may notice the weapon matrix gets rotated by 90 degress on the X axis as well. This is because they load in on their sides. Once again this seems pretty simple and follows the SRT order I keep reading about. My TagRotation matrix is the hand's rotation. HandTag.Position is its position in local space. CreateRotationY(PlayerRotation) is the player's rotation in world space, and the CollisionBody.Position is the player's world location. Everything seems to be in order, and almost works in game. However when the gun spawns and follows the player's hand it seems to be flipped on an axis every couple frames. Almost like the X or Y axis is being inversed then put right back. Its hard to explain and I am totally stumped. Even removing all my X axis fixes does nothing to solve the problem. Hopefully I explained everything enough as I am a bit new to this! Thanks!

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• Is the Leptonica implementation of 'Modified Median Cut' not using the median at all?

  - by TheCodeJunkie

  I'm playing around a bit with image processing and decided to read up on how color quantization worked and after a bit of reading I found the Modified Median Cut Quantization algorithm. I've been reading the code of the C implementation in Leptonica library and came across something I thought was a bit odd. Now I want to stress that I am far from an expert in this area, not am I a math-head, so I am predicting that this all comes down to me not understanding all of it and not that the implementation of the algorithm is wrong at all. The algorithm states that the vbox should be split along the lagest axis and that it should be split using the following logic The largest axis is divided by locating the bin with the median pixel (by population), selecting the longer side, and dividing in the center of that side. We could have simply put the bin with the median pixel in the shorter side, but in the early stages of subdivision, this tends to put low density clusters (that are not considered in the subdivision) in the same vbox as part of a high density cluster that will outvote it in median vbox color, even with future median-based subdivisions. The algorithm used here is particularly important in early subdivisions, and 3is useful for giving visible but low population color clusters their own vbox. This has little effect on the subdivision of high density clusters, which ultimately will have roughly equal population in their vboxes. For the sake of the argument, let's assume that we have a vbox that we are in the process of splitting and that the red axis is the largest. In the Leptonica algorithm, on line 01297, the code appears to do the following Iterate over all the possible green and blue variations of the red color For each iteration it adds to the total number of pixels (population) it's found along the red axis For each red color it sum up the population of the current red and the previous ones, thus storing an accumulated value, for each red note: when I say 'red' I mean each point along the axis that is covered by the iteration, the actual color may not be red but contains a certain amount of red So for the sake of illustration, assume we have 9 "bins" along the red axis and that they have the following populations 4 8 20 16 1 9 12 8 8 After the iteration of all red bins, the partialsum array will contain the following count for the bins mentioned above 4 12 32 48 49 58 70 78 86 And total would have a value of 86 Once that's done it's time to perform the actual median cut and for the red axis this is performed on line 01346 It iterates over bins and check they accumulated sum. And here's the part that throws me of from the description of the algorithm. It looks for the first bin that has a value that is greater than total/2 Wouldn't total/2 mean that it is looking for a bin that has a value that is greater than the average value and not the median ? The median for the above bins would be 49 The use of 43 or 49 could potentially have a huge impact on how the boxes are split, even though the algorithm then proceeds by moving to the center of the larger side of where the matched value was.. Another thing that puzzles me a bit is that the paper specified that the bin with the median value should be located, but does not mention how to proceed if there are an even number of bins.. the median would be the result of (a+b)/2 and it's not guaranteed that any of the bins contains that population count. So this is what makes me thing that there are some approximations going on that are negligible because of how the split actually takes part at the center of the larger side of the selected bin. Sorry if it got a bit long winded, but I wanted to be as thoroughas I could because it's been driving me nuts for a couple of days now ;)

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• W520 External monitor setup with Ubuntu 12.10

  - by user108372

  I just installed a fresh Ubuntu 12.10 64-Bit Desktop on my Lenovo W520. It looks like there are a lot of challenges around making it work with out of the box Nouveau drivers or propriety Nvidia drivers or Intel GPU. I looked at couple of notes on how to make it work with Bumblebee with Optimus Nvidia. None of them seems to work for 12.10. Anybody has a solid answer on this? It seems like a lot of people are suffering from this. Here is my xrandr output. Let me know if you need any additional information. Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 LVDS1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm 1920x1080 60.0*+ 59.9 50.0 1680x1050 60.0 59.9 1600x1024 60.2 1400x1050 60.0 1280x1024 60.0 1440x900 59.9 1280x960 60.0 1360x768 59.8 60.0 1152x864 60.0 1024x768 60.0 800x600 60.3 56.2 640x480 59.9 VGA1 disconnected (normal left inverted right x axis y axis) Thanks, Sef

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• Settings object with singleton pattern

  - by axis

  I need to build an object that will have only one instance because this Object is dedicated to the storage of vital settings for my application and I would like to avoid a misuse of this type or a conflict at run-time. The most popular solution for this, according to the internet, is the Singleton pattern. But I would like to know about other ideas or solutions for this; also I would like to know if other solutions can be much more easy to grasp for an user of this hypothetical library. Thanks.

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• Microsoft Excel not graphing

  - by SmartLemon

  Im not sure if this is a math question or a su question. The experiment was relating the period of one "bounce" when you hang a weight on a spring and let it bounce. I have this data here, one being mass and one being time. The time is an average of 5 trials, each one being and average of 20 bounces, to minimize human error. t 0.3049s 0.3982s 0.4838s 0.5572s 0.6219s 0.6804s 0.7362s 0.7811s 0.8328s 0.869s The mass is the mass that was used in each trial (they aren't going up in exact differences because each weight has a slight difference, nothing is perfect in the real world) m 50.59g 100.43g 150.25g 200.19g 250.89g 301.16g 351.28g 400.79g 450.43g 499.71g My problem is that I need to find the relationship between them, I know m = (k/4PI^2)*T^2 so I can work out k like that but we need to graph it. I can assume that the relationship is a sqrt relation, not sure on that one. But it appears to be the reverse of a square. Should it be 1/x^2 then? Either way my problem is still present, I have tried 1/x, 1/x^2, sqrt, x^2, none of them produce a straight line. The problem for SU is that when I go to graph the data on Excel I set the y axis data (which is the weights) and then when I go to set the x axis (which is the time) it just replaces the y axis with what I want to be the x axis, this is only happening when I have the sqrt of "m" as the y axis and I try to set the x axis as the time. The problem of math is that, am I even using the right thing? To get a straight line it would need to be x = y^1/2 right? I thought I was doing the right thing, it is what we were told to do. I'm just not getting anything that looks right.

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