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• Simple heart container script for 2D game (Unity)?

  - by N1ghtshade3

  I'm attempting to create a simple mobile game (C#) that involves a simple three-heart life system. After searching for hours online, many of the solutions use OnGUI (which is apparently horrible for performance) and the rest are too complicated for me to understand and add to my code. The other solutions involve using a single texture and just hiding part of it when damage is taken. In my game, however, the player should be able to go over three hearts (for example, every 100 points). Sebastian Lague's Zelda-Style Health is what I'm looking for, but even though it's a tutorial there is way too much going on that I don't need or can't customize to fit in mine. What I have so far is a script called HealthScript.cs which contains a variable lives. I have another script, PlayerPhysics.cs which calls HealthScript and subtracts a life when an enemy is hit. The part I don't get is actually drawing the hearts. I think I understand what needs to happen, I just am not experienced enough with Unity to know how. The Start function should draw three (or whatever lives is set to) hearts in the top right corner. Since the game should be resolution-independent to accommodate the various sizes of Android devices, I'd rather use scaling rather than PixelInset. When the player hits an enemy as detected by PlayerPhysics.cs, it should subtract from lives. I think that I have this working using this.GetComponent<HealthScript>().lives -= 1 but I'm not sure if it actually works. This should trigger a redraw of the hearts so that there are now two hearts. The same principle would apply for adding hearts when a score is reached, except when lives > maxHeartsPerRow, the new hearts should be drawn below the old ones. I realise I don't have much code to show but believe me; I've tried for quite some time to figure this out and have little to show for it. Any help at all would be welcome; it seems like it shouldn't take that much code to put an image on the screen for each life there is, but I haven't found anything yet. Thanks!

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• Programming and Ubiquitous Language (DDD) in a non-English domain

  - by Sandor Drieënhuizen

  I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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• Is inconsistent formatting a sign of a sloppy programmer?

  - by dreza

  I understand that everyone has their own style of programming and that you should be able to read other people's styles and accept it for what it is. However, would one be considered a sloppy programmer if one's style of coding was inconsistent across whatever standard they were working against? Some example of inconsistencies might be: Sometimes naming private variables with _ and sometimes not Sometimes having varying indentations within code blocks Not aligning braces up i.e. same column if using start using new line style Spacing not always consistent around operators i.e. p=p+1, p+=1 vs other times p =p+1 or p = p + 1 etc Is this even something that as a programmer I should be concerned with addressing? Or is it such a minor nit picking thing that at the end of the day I should just not worry about it and worry about what the end user sees and whether the code works rather than how it looks while working? Is it sloppy programming or just over obsessive nit picking? EDIT: After some excellent comments I realized I may have left out some information in my question. This question came about after reviewing another colleagues code check-in and noticing some of these things and then realizing that I've seen these kind of in-consistencies in previous check-ins. It then got me thinking about my code and whether I do the same things and noticed that I typically don't etc I'm not suggesting his technique is either bad or good in this question or whether his way of doing things is right or wrong. EDIT: To answer some queries to some more good feed back. The specific instance this review occurred in was using Visual Studio 2010 and programming in c# so I don't think the editor would cause any issues. In fact it should only help I would hope. Sorry if I left that piece of info out and it effects any current answers. I was trying to be a bit more generic in understanding if this would be considered sloppy etc. And to add an even more specific example of a code piece I saw during reading of the check-in: foreach(var block in Blocks) { // .. some other code in here foreach(var movement in movements) { movement.Moved.Zero(); } // the un-formatted brace } Such a minor thing I know, but many small things add up(???), and I did have to double glance at the code at the time to see where everything lined up I guess. Please note this code was formatted appropriately before this check-in. EDIT: After reading some great answers and varying thoughts, the summary I've taken from this was. It's not necessarily a sign of a sloppy programmer however as programmers we have a duty (to ourselves and other programmers) to make the code as readable as possible to assist in further ongoing development. However it can hint at inadequacies which is something that is only possible to review on a case by case (person by person) basis. There are many reasons why this might occur. They should be taken in context and worked through with the person/people involved if reasonable. We have a duty to try and help all programmers become better programmers! In the good old days when development was done using good old notepad (or other simple text editing tool) this occurred much more frequently. However we have the assistance of modern IDE's now so although we shouldn't necessarily become OTT about this, it should still probably be addressed to some degree. We as programmers vary in our standards, styles and approaches to solutions. However it seems that in general we all take PRIDE in our work and as a trait it is something that can stand programmers apart. Making something to the best of our abilities both internal (code) and external (end user result) goes along way to giving us that big fat pat on the back that we may not go looking for but swells our heart with pride. And finally to quote CrazyEddie from his post below. Don't sweat the small stuff

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• Automated Error Reporting = More Robust Software

  - by Laila

  I would like to tell you how to revolutionize your software development process </marketing hyperbole> On a more serious note, we (Red Gate's .NET Development team) recently rolled a new tool into our development process which has made our lives dramatically easier AND improved the quality of our software, and I (& one of our developers, Alex Davies) just wanted to take a quick moment to share the love. I work with a development team that takes pride in what they ship, so we take software testing rather seriously. For every development project we run, we allocate at least one software tester for every two developers, and we never ship software without first shipping early access releases and betas to get user feedback. And therein lies the challenge -encouraging users to provide consistent, useful feedback is a headache, but without that feedback, improving the software is. tricky. Until fairly recently, we used the standard (if long-winded) approach of receiving bug reports of variable quality via email or through our support forums. If that didn't give us enough information to reproduce the problem - which was most of the time - we had to enter into a time-consuming to-and-fro conversation with the end-user, to get scrape together the data we needed to work out where the problem lay. As I'm sure you're aware, this is painfully slow. To the delight of the team, we recently got to work with SmartAssembly, which lets us embed automated exception and error reporting into our software with very little pain, and we decided to do a little dogfooding. As a result, we've have made a really handy (if perhaps slightly obvious) discovery: As soon as we release a beta, or indeed any release of software, we now get tonnes of customer feedback through automated error reports. Making this process easier for our users has dramatically increased the amount (and quality) of feedback we get. From their point of view, they get an experience similar to Microsoft's error reporting, and process is essentially idiot-proof. From our side of things, we can now react much faster to the information we get, fixing the bugs and shipping a new-and-improved release, which our users rather appreciate. Smiles and hugs all round. Even more so because, as we're use SmartAssembly's Automated Error Reporting, we get to avoid having to spend weeks building an exception reporting mechanism. It takes just a few minutes to add reporting to a project, and we get a bunch of useful information back, like a stack trace and the values of all the local variables, which we can use to fix bugs. Happily, "Automated Error Reporting = More Robust Software" can actually be read two ways: we've found that we not only ship higher quality software, but we also release within a shorter time. We can ship stable software that our users are happy to upgrade to, and we then bask in the glory of lots of positive customer feedback. Once we'd starting working with SmartAssembly, we were curious to know how widespread error reporting was as a practice. Our product manager ran a survey in autumn last year, and found that 40% of software developers never really considered deploying error reporting. Considering how we've now got plenty of experience on the subject, one of our dev guys, Alex Davies, thought we should share what we've learnt, and he's kindly offered to host a webinar on delivering robust software with Automated Error Reporting. Drawing on our own in-house development experiences, he'll cover how to add error reporting to your program, how to actually use the error reports to fix bugs (don't snigger, not everyone's as bright as you), how to customize the error report dialog that your users see, and how to automatically get log files from your users' machine. The webinar will take place on Jan 25th (that's next week). It's free to attend, but you'll still need to register to hear Alex's dulcet tones.

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• Move a sphere along the swipe?

  - by gameOne

  I am trying to get a sphere curl based on the swipe. I know this has been asked many times, but still it's yearning to be answered. I have managed to add force on the direction of the swipe and it works near perfect. I also have all the swipe positions stored in a list. Now I would like to know how can the curl be achieved. I believe the the curve in the swipe can be calculated by the Vector dot product If theta is 0, then there is no need to add the swipe. If it is not, then add the curl. Maybe this condition is redundant if I managed to find how to curl the sphere along the swipe position The code that adds the force to sphere based on the swipe direction is as below: using UnityEngine; using System.Collections; using System.Collections.Generic; public class SwipeControl : MonoBehaviour { //First establish some variables private Vector3 fp; //First finger position private Vector3 lp; //Last finger position private Vector3 ip; //some intermediate finger position private float dragDistance; //Distance needed for a swipe to register public float power; private Vector3 footballPos; private bool canShoot = true; private float factor = 40f; private List<Vector3> touchPositions = new List<Vector3>(); void Start(){ dragDistance = Screen.height*20/100; Physics.gravity = new Vector3(0, -20, 0); footballPos = transform.position; } // Update is called once per frame void Update() { //Examine the touch inputs foreach (Touch touch in Input.touches) { /*if (touch.phase == TouchPhase.Began) { fp = touch.position; lp = touch.position; }*/ if (touch.phase == TouchPhase.Moved) { touchPositions.Add(touch.position); } if (touch.phase == TouchPhase.Ended) { fp = touchPositions[0]; lp = touchPositions[touchPositions.Count-1]; ip = touchPositions[touchPositions.Count/2]; //First check if it's actually a drag if (Mathf.Abs(lp.x - fp.x) > dragDistance || Mathf.Abs(lp.y - fp.y) > dragDistance) { //It's a drag //Now check what direction the drag was //First check which axis if (Mathf.Abs(lp.x - fp.x) > Mathf.Abs(lp.y - fp.y)) { //If the horizontal movement is greater than the vertical movement... if ((lp.x>fp.x) && canShoot) //If the movement was to the right) { //Right move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("right "+(lp.x-fp.x));//MOVE RIGHT CODE HERE canShoot = false; //rigidbody.AddForce((new Vector3((lp.x-fp.x)/30,10,16))*power); StartCoroutine(ReturnBall()); } else { //Left move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("left "+(lp.x-fp.x));//MOVE LEFT CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } } else { //the vertical movement is greater than the horizontal movement if (lp.y>fp.y) //If the movement was up { //Up move float y = (lp.y-fp.y)/Screen.height*factor; float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,y,16))*power); Debug.Log("up "+(lp.x-fp.x));//MOVE UP CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } else { //Down move Debug.Log("down "+lp+" "+fp);//MOVE DOWN CODE HERE } } } else { //It's a tap Debug.Log("none");//TAP CODE HERE } } } } IEnumerator ReturnBall() { yield return new WaitForSeconds(5.0f); rigidbody.velocity = Vector3.zero; rigidbody.angularVelocity = Vector3.zero; transform.position = footballPos; canShoot =true; isKicked = false; } }

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• OEG11gR2 integration with OES11gR2 Authorization with condition

  - by pgoutin

  Introduction This OES use-case has been defined originally by Subbu Devulapalli (http://accessmanagement.wordpress.com/).  Based on this OES museum use-case, I have developed the OEG11gR2 policy able to deal with the OES authorization with condition. From an OEG point of view, the way to deal with OES condition is to provide with the OES request some Environmental / Context Attributes.   Museum Use-Case  All painting in the museum have security sensors, an alarm goes off when a person comes too close a painting. The employee designated for maintenance needs to use their ID and disable the alarm before maintenance. You are the Security Administrator for the museum and you have been tasked with creating authorization policies to manage authorization for different paintings. Your first task is to understand how paintings are organized. Asking around, you are surprised to see that there isno formal process in place, so you need to start from scratch. the museum tracks the following attributes for each painting 1. Name of the work 2. Painter 3. Condition (good/poor) 4. Cost You compile the list of paintings  Name of Painting  Painter  Paint Condition  Cost  Mona Lisa  Leonardo da Vinci  Good  100  Magi  Leonardo da Vinci  Poor  40  Starry Night  Vincent Van Gogh  Poor  75  Still Life  Vincent Van Gogh  Good  25 Being a software geek who doesn’t (yet) understand art, you feel that price(or insurance price) of a painting is the most important criteria. So you feel that based on years-of-experience employees can be tasked with maintaining different paintings. You decide that paintings worth over 50 cost should be only handled by employees with over 20 years of experience and employees with less than 10 years of experience should not handle any painting. Lets us start with policy modeling. All paintings have a common set of attributes and actions, so it will be good to have them under a single Resource Type. Based on this resource type we will create the actual resources. So our high level model is: 1) Resource Type: Painting which has action manage and the following four attributes a) Name of the work b) Painter c) Condition (good/poor) d) Cost 2) To keep things simple lets use painting name for Resource name (in real world you will try to use some identifier which is unique, because in future we may end up with more than one painting which has the same name.) 3) Create Resources based on the previous table 4) Create an identity attribute Experience (Integer) 5) Create the following authorization policies a) Allow employees with over 20 years experience to access all paintings b) Allow employees with 10 – 20 years of experience to access painting which cost less than 50 c) Deny access to all paintings for employees with less than 10 year of experience OES Authorization Configuration We do need to create 2 authorization policies with specific conditions a) Allow employees with over 20 years experience to access all paintings b) Allow employees with 10 – 20 years of experience to access painting which cost less than 50 c) Deny access to all paintings for employees with less than 10 year of experience We don’t need an explicit policy for Deny access to all paintings for employees with less than 10 year of experience, because Oracle Entitlements Server will automatically deny if there is no matching policy. OEG Policy The OEG policy looks like the following The 11g Authorization filter configuration is similar to :  The ${PAINTING_NAME} and ${USER_EXPERIENCE} variables are initialized by the "Retrieve from the HTTP header" filters for testing purpose. That's to say, under Service Explorer, we need to provide 2 attributes "Experience" & "Painting" following the OES 11g Authorization filter described above.

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• Essential Links for the SharePoint Client Side Developer

  - by Mark Rackley

  Front End Developer? Client Side Developer? Middle Tier??? I’m covering all my bases.  Regardless, I’m sick and tired of Googling with Bing when I forget where information that I need often is located. I was getting ready to bookmark some of them when it hit me… “Hey Mark… (I don’t actually refer to myself in the third person), Why don’t you put the links in a blog so that it looks like you are being helpful!” I can’t tell you how many times I’ve had to go back to some of my old blogs to remember how I did something. Seriously people, you need to start a blog, it’s the best way to remember how the frick you got something to work… and it looks like you are being helpful when in reality you are just forgetful.  So… where was I? Oh yeah.. essential information that I’ve needed from time to time when I was not using Visual Studio. All of this info has come in handy from time to time. Know about these things and keep them in your tool belt, it’s amazing the stuff you can accomplish with just knowing where to look. What Why SPServices Widely used library written by Marc Anderson used to call SharePoint Web Services with jQuery jQuery For SPServices and other cool stuff Easy Tabs Essential tool for quick page enhancements. This widely used too from Christophe Humbert groups multiple web parts into one tabbed display. Very quick and easy way to get oohs and ahs from End Users. Convert Calculated Columns to HTML Also from Christophe, I use this script all the time to convert html in my calculated columns to actually display as html and not with the tags. Unlocking the Mysteries of Data View Web Part XSL Tags This blog series from Marc Anderson makes it very easy to understand what’s going on with all those weird xsl tags in your data view web parts. Essential to make those things do what you want them to do. Creating Parent / Child list relationships (2007) Creating Parent / Child list relationships (2010) By far my most viewed blog posts (tens and tens of thousands).  I have posts for both 2007 and 2010 that walk you through automatically setting the lookup id on a list to its “parent”. Set SharePoint Form fields using Query String Variables Also widely read, this one walks you through taking a variable from your Query String and set a form field to that value.   Hmmm… I KNOW there are more, but I’m tired and drawing a blank.  I’ll try to add them when I remember them (or need them again and think “Oh, I forgot to add that one”) But it’s a start, and please feel free to add your own in the comments… So, it’s YOUR turn to be helpful. What little tip or trick do you find yourself using ALL the time that you think everyone should know about??

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• HOWTO Turn off SPARC T4 or Intel AES-NI crypto acceleration.

  - by darrenm

  Since we released hardware crypto acceleration for SPARC T4 and Intel AES-NI support we have had a common question come up: 'How do I test without the hardware crypto acceleration?'. Initially this came up just for development use so developers can do unit testing on a machine that has hardware offload but still cover the code paths for a machine that doesn't (our integration and release testing would run on all supported types of hardware anyway).  I've also seen it asked in a customer context too so that we can show that there is a performance gain from the hardware crypto acceleration, (not just the fact that SPARC T4 much faster performing processor than T3) and measure what it is for their application. With SPARC T2/T3 we could easily disable the hardware crypto offload by running 'cryptoadm disable provider=n2cp/0'.  We can't do that with SPARC T4 or with Intel AES-NI because in both of those classes of processor the encryption doesn't require a device driver instead it is unprivileged user land callable instructions. Turns out there is away to do this by using features of the Solaris runtime loader (ld.so.1). First I need to expose a little bit of implementation detail about how the Solaris Cryptographic Framework is implemented in Solaris 11.  One of the new Solaris 11 features of the linker/loader is the ability to have a single ELF object that has multiple different implementations of the same functions that are selected at runtime based on the capabilities of the machine.  The alternate to this is having the application coded to call getisax() and make the choice itself.  We use this functionality of the linker/loader when we build the userland libraries for the Solaris Cryptographic Framework (specifically libmd.so, and the unfortunately misnamed due to historical reasons libsoftcrypto.so) The Solaris linker/loader allows control of a lot of its functionality via environment variables, we can use that to control the version of the cryptographic functions we run.  To do this we simply export the LD_HWCAP environment variable with values that tell ld.so.1 to not select the HWCAP section matching certain features even if isainfo says they are present.  For SPARC T4 that would be: export LD_HWCAP="-aes -des -md5 -sha256 -sha512 -mont -mpul" and for Intel systems with AES-NI support: export LD_HWCAP="-aes" This will work for consumers of the Solaris Cryptographic Framework that use the Solaris PKCS#11 libraries or use libmd.so interfaces directly.  It also works for the Oracle DB and Java JCE.  However does not work for the default enabled OpenSSL "t4" or "aes-ni" engines (unfortunately) because they do explicit calls to getisax() themselves rather than using multiple ELF cap sections. However we can still use OpenSSL to demonstrate this by explicitly selecting "pkcs11" engine  using only a single process and thread.  $ openssl speed -engine pkcs11 -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 54170.81k 187416.00k 489725.70k 805445.63k 1018880.00k $ LD_HWCAP="-aes" openssl speed -engine pkcs11 -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 29376.37k 58328.13k 79031.55k 86738.26k 89191.77k We can clearly see the difference this makes in the case where AES offload to the SPARC T4 was disabled. The "t4" engine is faster than the pkcs11 one because there is less overhead (again on a SPARC T4-1 using only a single process/thread - using -multi you will get even bigger numbers). $ openssl speed -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 85526.61k 89298.84k 91970.30k 92662.78k 92842.67k Yet another cool feature of the Solaris linker/loader, thanks Rod and Ali. Note these above openssl speed output is not intended to show the actual performance of any particular benchmark just that there is a significant improvement from using hardware acceleration on SPARC T4. For cryptographic performance benchmarks see the http://blogs.oracle.com/BestPerf/ postings.

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• perl comparing 2 data file as array 2D for finding match one to one [migrated]

  - by roman serpa

  I'm doing a program that uses combinations of variables ( combiData.txt 63 rows x different number of columns) for analysing a data table ( j1j2_1.csv, 1000filas x 19 columns ) , to choose how many times each combination is repeated in data table and which rows come from (for instance, tableData[row][4]). I have tried to compile it , however I get the following message : Use of uninitialized value $val in numeric eq (==) at rowInData.pl line 34. Use of reference "ARRAY(0x1a2eae4)" as array index at rowInData.pl line 56. Use of reference "ARRAY(0x1a1334c)" as array index at rowInData.pl line 56. Use of uninitialized value in subtraction (-) at rowInData.pl line 56. Modification of non-creatable array value attempted, subscript -1 at rowInData.pl line 56. nothing This is my code: #!/usr/bin/perl use strict; use warnings; my $line_match; my $countTrue; open (FILE1, "<combiData.txt") or die "can't open file text1.txt\n"; my @tableCombi; while(<FILE1>) { my @row = split(' ', $_); push(@tableCombi, \@row); } close FILE1 || die $!; open (FILE2, "<j1j2_1.csv") or die "can't open file text1.txt\n"; my @tableData; while(<FILE2>) { my @row2 = split(/\s*,\s*/, $_); push(@tableData, \@row2); } close FILE2 || die $!; #function transform combiData.txt variable (position ) to the real value that i have to find in the data table. sub trueVal($){ my ($val) = $_[0]; if($val == 7){ return ('nonsynonymous_SNV'); } elsif( $val == 14) { return '1'; } elsif( $val == 15) { return '1';} elsif( $val == 16) { return '1'; } elsif( $val == 17) { return '1'; } elsif( $val == 18) { return '1';} elsif( $val == 19) { return '1';} else { print 'nothing'; } } #function IntToStr ( ) , i'm not sure if it is necessary) that transforms $ to strings , to use the function <eq> in the third loop for the array of combinations compared with the data array . sub IntToStr { return "$_[0]"; } for my $combi (@tableCombi) { $line_match = 0; for my $sheetData (@tableData) { $countTrue=0; for my $cell ( @$combi) { #my $temp =\$tableCombi[$combi][$cell] ; #if ( trueVal($tableCombi[$combi][$cell] ) eq $tableData[$sheetData][ $tableCombi[$combi][$cell] - 1 ] ){ #if ( IntToStr(trueVal($$temp )) eq IntToStr( $tableData[$sheetData][ $$temp-1] ) ){ if ( IntToStr(trueVal($tableCombi[$combi][$cell]) ) eq IntToStr($tableData[$sheetData][ $tableCombi[$combi][$cell] -1]) ){ $countTrue++;} if ($countTrue==@$combi){ $line_match++; #if ($line_match < 50){ print $tableData[$sheetData][4]." "; #} } } } print $line_match." \n"; }

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• Time passage arithmetic explanation

  - by Cyber Axe

  I ported this from http://www.effectgames.com/effect/article.psp.html/joe/Old_School_Color_Cycling_with_HTML5 some time ago. However i'm now wanting to modify it for the purpose of changing it from floating point to fixed point maths for enhanced efficiency (for those who are going to talk about premature optimization and what not, i want to have my entire engine in fixed point both as a learning process for me and so i can port code more easily to systems in the future that dont have native floating points such as arm cpus) My initial conversion to fixed points just resulted in the cycling stuck on either the first or last frame of cycling. Plus it would be nice to understand better how it works so i can add more options and so forth in the future, my maths however sucks and the comments are limited so i don't really know how the maths work for determining the frame it shoud use (cycleAmount) I was also a beginner when i ported it as i had no idea between floating points and integers and what not. So in summary my question is, can anyone give an explination of the arithmatic used for determining the cycleAmount (which determings the "frame" of the cycle) This is the working floating point maths version of the code: public final void cycle(Colour[] sourceColours, double timeNow, double speedAdjust) { // Cycle all animated colour ranges in palette based on timestamp. sourceColours = sourceColours.clone(); int cycleSize; double cycleRate; double cycleAmount; Cycle cycle; for (int i = 0, len = cycles.length; i < len; ++i) { cycle = cycles[i]; cycleSize = (cycle.HIGH - cycle.LOW) + 1; cycleRate = cycle.RATE / (int) (CYCLE_SPEED / speedAdjust); cycleAmount = 0; if (cycle.REVERSE < 3) { // Standard Cycle cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); if (cycle.REVERSE < 1) { cycleAmount = cycleSize - cycleAmount; // If below 1 make sure its not reversed. } } else if (cycle.REVERSE == 3) { // Ping-Pong cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize << 1); if (cycleAmount >= cycleSize) { cycleAmount = (cycleSize * 2) - cycleAmount; } } else if (cycle.REVERSE < 6) { // Sine Wave cycleAmount = DFLOAT_MOD((timeNow / (1000 / cycleRate)), cycleSize); cycleAmount = Math.sin((cycleAmount * 3.1415926 * 2) / cycleSize) + 1; if (cycle.REVERSE == 4) { cycleAmount *= (cycleSize / 4); } else if (cycle.REVERSE == 5) { cycleAmount *= (cycleSize >> 1); } } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } if (USE_BLEND_SHIFT) { blendShiftColours(sourceColours, cycle, cycleAmount); } else { shiftColours(sourceColours, cycle, cycleAmount); } if (cycle.REVERSE == 2) { reverseColours(sourceColours, cycle); } } colours = sourceColours; } // This utility function allows for variable precision floating point modulus. private double DFLOAT_MOD(final double d, final double b) { return (Math.floor(d * PRECISION) % Math.floor(b * PRECISION)) / PRECISION; }

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• Are SQL Injection vulnerabilities in a PHP application acceptable if mod_security is enabled?

  - by Austin Smith

  I've been asked to audit a PHP application. No framework, no router, no model. Pure PHP. Few shared functions. HTML, CSS, and JS all mixed together. I've discovered numerous places where SQL injection would be easily possible. There are other problems with the application (XSS vulnerabilities, rampant inline CSS, code copy-pasted everywhere) but this is the biggest. Sometimes they escape inputs, not using a prepared query or even mysql_real_escape_string(), mind you, but using addslashes(). Often, though, their queries look exactly like this (pasted from their code but with columns and variable names changed): $user = mysql_query("select * from profile where profile_id='".$_REQUEST["profile_id"]."'"); The developers in question claimed that they were unable to hack their application. I tried, and found mod_security to be enabled, resulting in HTTP 406 for some obvious SQL injection attacks. I believe there to be sophisticated workarounds for mod_security, but I don't have time to chase them down. They claim that this is a "conceptual" matter and not a "practical" one since the application can't easily be hacked. Their internal auditor agreed that there were problems, but emphasized the conceptual nature of the issues. They also use this conceptual/practical argument to defend against inline CSS and JS, absence of code organization, XSS vulnerabilities, and massive amounts of repetition. My client (rightly so, perhaps) just wants this to go away so they can launch their product. The site works. You can log in, do what you need to do, and things are visibly functional, if slow. SQL Injection would indeed be hard to do, given mod_security. Further, their talk of "conceptual vs. practical" is rhetorically brilliant, considering that my client doesn't understand web application security. I worry that they've succeeded in making me sound like an angry puritan. In many ways, this is a problem of politics, not technology, but I am at a loss. As a developer, I want to tell them to toss the whole project and start over with a new team, but I face a strong defense from the team that built it and a client who really needs to ship their product. Is my position here too harsh? Even if they fix the SQL Injection and XSS problems can I ever endorse the release of an unmaintainable tangle of spaghetti code?

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• Eclipse no longer useful

  - by dgood1

  When I got my Eclipse from the Ubuntu Software Center, it was good and worked fine. I could work on Java projects fine. This week I was required to add ADT and tried the ADT-bundle, assuming it had everthing I needed, seeing that the SDK had more steps. So now, I can create Android apps using the ADT-bundle. I tried to work on my java projects again and I now discovered: I can't run my java projects: "The selection cannot be launched. And there are no recent launches." error. I also believe Eclipse doesn't know it's a java program because it all in black and white. Not the usual green/blue/red/black things when making comments, variables and Strings. I can't make new projects of ANYTHING unless I use the adt-bundle. New project only offers CVS (whatever that is) My perspectives seem limited. I remembered more choices and now I'm limited to [Java], Resource, CVS Repository, debug, Team Sync. I was told to be able to use perspectives to swap between Android and Java developing. Even after the ADT installation using "Install new Software",nothing. I can't uninstall/purge/remove Eclipse via the terminal. I tried removing it then reinstalling it via the Ubuntu Software Cetner. No results other than it's temporary removal. (Possibly unrelated) A large number of repositories are not found when updating Eclipse. (See Step 8 in Summary of what I did...) Although, on checking the versions and installation history, I confirmed Android and Java are installed. It probably just doesn't know it's there. Eclipse Indigo: Version: 3.7.2 Build id: I20110613-1736 Summary of what I did before and during the problem: Downloaded adt-bundle. Attempted instructions from teacher. (Install new Software) (Failed but other than an annoying "can't find repository" during each update, no damage to report) (Fixed) Ran "eclipse" executable from the adt-bundle. Updated Eclipse. (After restart, I noticed the problem) NOTE: other than window arrangement, I had no customizations. Played around with the Windowspreferences and Projectpropertied. Restored to default settings after no results. Tried "apt-get purge eclipse". Couldn't find Eclipse so, nothing happened. Used Software center. No results. Tried swapping workspaces. I tried different folder, deeper folder, renaming. All return the same problem. Deleted adt-bundle (browsed folders then delete). Got Adt-sdk only. Installed. Can't find any changes other than some disk space usage. Of course, I can't make Android apps until I unzip the bundle again. WindowsPreferencesInstall/UpdateAvailable Software Sites, Checked as many repositories as possible, then updated. Still nothing. I'm about to get a second try on uninstalling it, because I think my last action will just be taking up space. But I'll wait for tomorrow, in case the answer will help. Any thoughts?

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• Undefined fireball movement behavior

  - by optimisez

  Demonstration video I try to do after the player shoot 10 times of fireball, then delete all the fireball objects and recreate a 10 new set of fireball objects. I did it but there is a weird bug happens that sometimes the fireball will come out from top and move to the right after shooting a few times. All the 10 fireballs should follow the player all the time and all the fireball should come out from player even after a new set of fireballs is recreated. Any ideas to fix it? Variables typedef struct gameObject{ float X; float Y; int length; int height; bool action; }; // Fireball #define FIREBALL_NUM 10 LPDIRECT3DTEXTURE9 fireball = NULL; RECT fireballRect; gameObject *fireballDest = new gameObject[FIREBALL_NUM]; int iFireBallAnimation; int fireballCount = 0; Set up Fireball void setUpFireBall() { // Initialize destination rectangle, rectangle height and length for (int i = 0; i < FIREBALL_NUM; i++) { fireballDest[i].X = 0; fireballDest[i].Y = 0; fireballDest[i].length = fireballRect.right - fireballRect.left; fireballDest[i].height = fireballRect.bottom - fireballRect.top; } iFireBallAnimation = fireballRect.right - fireballRect.left; // Initialize boolean for (int i = 0; i < FIREBALL_NUM; i++) { fireballDest[i].action = false; } } Initialize fireball void initFireball() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "fireball.png", 512, 512, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 0), NULL, NULL, &fireball); // Initialize source rectangle fireballRect.left = 0; fireballRect.top = 256; fireballRect.right = 64; fireballRect.bottom = 320; setUpFireBall(); } Update fireball void update() { updateAnimation(); updateAI(); updatePhysics(); updateGameState(); } void updatePhysics() { motion(); collison(); } void motion() { playerMove(); playerJump(); playerGravity(); shootFireball(); fireballFollowPlayer(); } void shootFireball() { if (keyArr['Z']) fireballDest[fireballCount].action = true; if (fireballDest[fireballCount].action) { fireballDest[fireballCount].X += 10; if (fireballDest[fireballCount].X > 800) fireballCount++; } } void fireballFollowPlayer() { for (int i = 0; i < FIREBALL_NUM; i++) { if (fireballDest[i].action == false) { fireballDest[i].X = playerDest.X - 30; fireballDest[i].Y = playerDest.Y - 14; } } } void updateGameState() { // When no more fireball left, rearm fireball if (fireballCount == FIREBALL_NUM) { delete[] fireballDest; fireballDest = new gameObject[10]; fireballCount = 0; setUpFireBall(); } } Render fireball void renderFireball() { for (int i = 0; i < FIREBALL_NUM; i++) { if (fireballDest[i].action) sprite->Draw(fireball, &fireballRect, NULL, &D3DXVECTOR3(fireballDest[i].X, fireballDest[i].Y, 0), D3DCOLOR_XRGB(255,255, 255)); } }

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• Node.js Lockstep Multiplayer Architecture

  - by Wakaka

  Background I'm using the lockstep model for a multiplayer Node.js/Socket.IO game in a client-server architecture. User input (mouse or keypress) is parsed into commands like 'attack' and 'move' on the client, which are sent to the server and scheduled to be executed on a certain tick. This is in contrast to sending state data to clients, which I don't wish to use due to bandwidth issues. Each tick, the server will send the list of commands on that tick (possibly empty) to each client. The server and all clients will then process the commands and simulate that tick in exactly the same way. With Node.js this is actually quite simple due to possibility of code sharing between server and client. I'll just put the deterministic simulator in the /shared folder which can be run by both server and client. The server simulation is required so that there is an authoritative version of the simulation which clients cannot alter. Problem Now, the game has many entity classes, like Unit, Item, Tree etc. Entities are created in the simulator. However, for each class, it has some methods that are shared and some that are client-specific. For instance, the Unit class has addHp method which is shared. It also has methods like getSprite (gets the image of the entity), isVisible (checks if unit can be seen by the client), onDeathInClient (does a bunch of stuff when it dies only on the client like adding announcements) and isMyUnit (quick function to check if the client owns the unit). Up till now, I have been piling all the client functions into the shared Unit class, and adding a this.game.isServer() check when necessary. For instance, when the unit dies, it will call if (!this.game.isServer()) { this.onDeathInClient(); }. This approach has worked pretty fine so far, in terms of functionality. But as the codebase grew bigger, this style of coding seems a little strange. Firstly, the client code is clearly not shared, and yet is placed under the /shared folder. Secondly, client-specific variables for each entity are also instantiated on the server entity (like unit.sprite) and can run into problems when the server cannot instantiate the variable (it doesn't have Image class like on browsers). So my question is, is there a better way to organize the client code, or is this a common way of doing things for lockstep multiplayer games? I can think of a possible workaround, but it does have its own problems. Possible workaround (with problems) I could use Javascript mixins that are only added when in a browser. Thus, in the /shared/unit.js file in the /shared folder, I would have this code at the end: if (typeof exports !== 'undefined') module.exports = Unit; else mixin(Unit, LocalUnit); Then I would have /client/localunit.js store an object LocalUnit of client-side methods for Unit. Now, I already have a publish-subscribe system in place for events in the simulator. To remove the this.game.isServer() checks, I could publish entity-specific events whenever I want the client to do something. For instance, I would do this.publish('Death') in /shared/unit.js and do this.subscribe('Death', this.onDeathInClient) in /client/localunit.js. But this would make the simulator's event listeners list on the server and the client different. Now if I want to clear all subscribed events only from the shared simulator, I can't. Of course, it is possible to create two event subscription systems - one client-specific and one shared - but now the publish() method would have to do if (!this.game.isServer()) { this.publishOnClient(event); }. All in all, the workaround off the top of my head seems pretty complicated for something as simple as separating the client and shared code. Thus, I wonder if there is an established and simpler method for better code organization, hopefully specific to Node.js games.

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• Workflow versioning

  - by Nitra

  I believe I have a fundamental misunderstanding when it comes to workflow engines which I would appreciate if you could help me sort out. I'm not sure if my misunderstanding is specific to the workflow engine I'm using, or if it's a general misunderstanding. I happen to use Windows Workflow Foundation (WWF). TLDR-version WWF allows you to implement business processes in long-running workflows (think months or even years). When started, the workflows can't be changed. But what business process can't change at any time? And if a business process changes, wouldn't you want your software to reflect this change for already started 'instances' of the business process? What am I missing? Background In WWF you define a workflow by combining a set of activites. There are different types of activities - some of them are for flow control, such as the IfElseActivity and the WhileActivty while others allows you to perform actual tasks, such as the CodeActivity wich allows you to run .NET code and the InvokeWebServiceActivity which allows you to call web services. The activites are combined to a workflow using a visual designer. You pretty much drag-and-drop activities from a toolbox to a designer area and connect the activites to each other. The workflow and activities have input paramters, output parameters and variables. We have a single workflow which sometimes runs in a matter of a few days, but it may run for 5-6 months. WWF takes care of persisting the workflow state (what activity are we currently executing, what are the variable values and so on). So far I think WWF makes sense. Some people will prefer to implement a software representation of a business process using a visual designer over writing all of it in code. So what's the issue then? What I don't really get is the following: WWF is designed to take care of long-running workflows. But at the same time, WWF has no built-in functionality which allows you to modify the running workflows. So if you model a business process using a workflow and run that for 6 months, you better hope that the business process does not change. Because if it do, you'll have to have multiple versions of the workflow executing at the same time. This seems like a fundamental design mistake to me, but at the same time it seems more likely that I've misunderstood something. For us, this has had some real-world effects: We release new versions every month, but some workflows may run for a year. This means that we have several versions of the workflow running in parallell, in other words several versions of the business logics. This is the same as having many differnt versions of your code running in production in the same system at the same time, which becomes a bit hard to understand for users. (depending on on whether they clicked a 'Start' button 9 or 10 months ago, the software will behave differently) Our workflow refers to different types of entities and since WWF now has persisted and serialized these we can't really refactor the entities since then existing workflows can't be resumed (deserialization will fail We've received some suggestions on how to handle this When we create a new version of the workflow, cancel all running workflows and create new ones. But in our workflows there's a lot of manual work involved and if we start from scratch a lot of people has to re-do their work. Track what has been done in the workflow and when you create a new one skip activites which have already been executed. I feel that this alternative may work for simple workflows, but it becomes hairy to automatically figure out what activities to skip if there's major refactoring done to a workflow. When we create a new version of the workflow, upgrade old versions using the new WWF 4.5 functionality for upgrading workflows. But then we would have to skip using the visual designer and write code to inject activities in the right places in the workflow. According to MSDN, this upgrade functionality is only intended for minor bug fixes and not larger changes. What am I missing?

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• Card deck and sparse matrix interview questions

  - by MrDatabase

  I just had a technical phone screen w/ a start-up. Here's the technical questions I was asked ... and my answers. What do think of these answers? Feel free to post better answers :-) Question 1: how would you represent a standard 52 card deck in (basically any language)? How would you shuffle the deck? Answer: use an array containing a "Card" struct or class. Each instance of card has some unique identifier... either it's position in the array or a unique integer member variable in the range [0, 51]. Shuffle the cards by traversing the array once from index zero to index 51. Randomly swap ith card with "another card" (I didn't remember how this shuffle algorithm works exactly). Watch out for using the same probability for each card... that's a gotcha in this algorithm. I mentioned the algorithm is from Programming Pearls. Question 2: how to represent a large sparse matrix? the matrix can be very large... like 1000x1000... but only a relatively small number (~20) of the entries are non-zero. Answer: condense the array into a list of the non-zero entries. for a given entry (i,j) in the array... "map" (i,j) to a single integer k... then use k as a key into a dictionary or hashtable. For the 1000x1000 sparse array map (i,j) to k using something like f(i, j) = i + j * 1001. 1001 is just one plus the maximum of all i and j. I didn't recall exactly how this mapping worked... but the interviewer got the idea (I think). Are these good answers? I'm wondering because after I finished the second question the interviewer said the dreaded "well that's all the questions I have for now." Cheers!

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• Should UTF-16 be considered harmful?

  - by Artyom

  I'm going to ask what is probably quite a controversial question: "Should one of the most popular encodings, UTF-16, be considered harmful?" Why do I ask this question? How many programmers are aware of the fact that UTF-16 is actually a variable length encoding? By this I mean that there are code points that, represented as surrogate pairs, take more than one element. I know; lots of applications, frameworks and APIs use UTF-16, such as Java's String, C#'s String, Win32 APIs, Qt GUI libraries, the ICU Unicode library, etc. However, with all of that, there are lots of basic bugs in the processing of characters out of BMP (characters that should be encoded using two UTF-16 elements). For example, try to edit one of these characters: 𝄞 (U+1D11E) MUSICAL SYMBOL G CLEF 𝕥 (U+1D565) MATHEMATICAL DOUBLE-STRUCK SMALL T 𝟶 (U+1D7F6) MATHEMATICAL MONOSPACE DIGIT ZERO 𠂊 (U+2008A) Han Character You may miss some, depending on what fonts you have installed. These characters are all outside of the BMP (Basic Multilingual Plane). If you cannot see these characters, you can also try looking at them in the Unicode Character reference. For example, try to create file names in Windows that include these characters; try to delete these characters with a "backspace" to see how they behave in different applications that use UTF-16. I did some tests and the results are quite bad: Opera has problem with editing them (delete required 2 presses on backspace) Notepad can't deal with them correctly (delete required 2 presses on backspace) File names editing in Window dialogs in broken (delete required 2 presses on backspace) All QT3 applications can't deal with them - show two empty squares instead of one symbol. Python encodes such characters incorrectly when used directly u'X'!=unicode('X','utf-16') on some platforms when X in character outside of BMP. Python 2.5 unicodedata fails to get properties on such characters when python compiled with UTF-16 Unicode strings. StackOverflow seems to remove these characters from the text if edited directly in as Unicode characters (these characters are shown using HTML Unicode escapes). WinForms TextBox may generate invalid string when limited with MaxLength. It seems that such bugs are extremely easy to find in many applications that use UTF-16. So... Do you think that UTF-16 should be considered harmful?

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• The inevitable Hello World post!

  - by brendonpage

  Greetings to anyone reading this! This is my first of hopefully many posts. I would like to use this post to introduce myself and to let you know what to expect from this blog in future. Okay so a bit about myself. In case you missed the name of this blog, my name is Brendon Page! I am a Software Developer from South Africa and work for a small company who’s main focus is producing software for the kitchen cupboard industry, although from time to time we do produce custom solutions for other industries. I work in a small team of 3, including myself, and am fortunate enough to work from home! I have been involved in IT since 1996, which is when I got my first PC, and started working as a junior programmer in 2003. Outside of work I enjoy playing squash, PC Games and of course LANing with my friends. If I get any free time between all of that I will usually dedicate some of it to a personal project, these are mainly prototypes for an idea I have had or for something that could be useful at work. I was in 2 minds on whether to include a photo of myself. The reason for this was because while I was looking for a suitable photo to use, it dawned on me how much time I dedicate to pulling funny faces in photos! I also realized how little I shave, which I blame completely on working form home. So after much debate here I am, funny face, beard and all!   Now that you know a bit about me lets move onto what expect from this blog. I work predominantly with Microsoft technologies so most if not all of my posts will be related to something Microsoft. Since most of my job entails Software Development you can expect a lot of posts which will deal with the .NET Framework. I am currently working on a large Silverlight project, so my first few posts will be targeted at in that direction. I will be striving to make the content of my posts as useful as possible from both an explanation and code perspective, I aim to include a working solution for every post, which I will put up on my skydrive for download. Here is what I have planned for my next few posts: Where did my session variables go?  Here I will take you through the lessons I learnt the hard way about the ASP.NET session. I am not going to go into to much depth in this post, as there is already a lot of information available on it. I mainly want to cover it in an effort to keep the scope creep of my posts to a minimum, some the solutions I upload will use it and I would like to have a post that I can reference to explain why I am doing something a certain way. Uploading files through SIlverlight Again there is a lot of existing information on this topic, so I wont be going into to much depth, but I will be using the solution from this as a base for my next post. Generating and Displaying DeepZoom images dynamically in Silverlight Well the title pretty much speaks for it’s self on this one. As I mentioned I will be building off the solution that I create in my ‘Uploading files through Silverlight’ post. Securing DeepZoom images using a custom implementation of the MultiScaleTileSource In this post I will look at the privacy issue surrounding the default usage of DeepZoom images in Silverlight and how to overcome it. This makes the use of DeepZoom in privacy conscious applications more viable. Thanks to anyone who actually read this post! I look forward to producing more which will hopefully be helpful to you.

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• How the SPARC T4 Processor Optimizes Throughput Capacity: A Case Study

  - by Ruud

  This white paper demonstrates the architected latency hiding features of Oracle’s UltraSPARC T2+ and SPARC T4 processors That is the first sentence from this technical white paper, but what does it exactly mean? Let's consider a very simple example, the computation of a = b + c. This boils down to the following (pseudo-assembler) instructions that need to be executed: load @b, r1 load @c, r2 add r1,r2,r3 store r3, @a The first two instructions load variables b and c from an address in memory (here symbolized by @b and @c respectively). These values go into registers r1 and r2. The third instruction adds the values in r1 and r2. The result goes into register r3. The fourth instruction stores the contents of r3 into the memory address symbolized by @a. If we're lucky, both b and c are in a nearby cache and the load instructions only take a few processor cycles to execute. That is the good case, but what if b or c, or both, have to come from very far away? Perhaps both of them are in the main memory and then it easily takes hundreds of cycles for the values to arrive in the registers. Meanwhile the processor is doing nothing and simply waits for the data to arrive. Actually, it does something. It burns cycles while waiting. That is a waste of time and energy. Why not use these cycles to execute instructions from another application or thread in case of a parallel program? That is exactly what latency hiding on the SPARC T-Series processors does. It is a hardware feature totally transparent to the user and application. As soon as there is a delay in the execution, the hardware uses these otherwise idle cycles to execute instructions from another process. As a result, the throughput capacity of the system improves because idle cycles are no longer wasted and therefore more jobs can be run per unit of time. This feature has been in the SPARC T-series from the beginning, so why this paper? The difference with previous publications on this topic is in the amount of detail given. How this all works under the hood is fully explained using two example programs. Starting from the assembly language instructions, it is demonstrated in what way these programs execute. To really see what is happening we go down to the processor pipeline level, where the gaps in the execution are, and show in what way these idle cycles are filled by other copies of the same program running simultaneously. Both the SPARC T4 as well as the older UltraSPARC T2+ processor are covered. You may wonder why the UltraSPARC T2+ is included. The focus of this work is on the SPARC T4 processor, but to explain the basic concept of latency hiding at this very low level, we start with the UltraSPARC T2+ processor because it is architecturally a much simpler design. From the single issue, in-order pipelines of this processor we then shift gears and cover how this all works on the much more advanced dual issue, out-of-order architecture of the T4. The analysis and performance experiments have been conducted on both processors. The results depend on the processor, but in all cases the theoretical estimates are confirmed by the experiments. If you're interested to read a lot more about this and find out how things really work under the hood, you can download a copy of the paper here. A paper like this could not have been produced without the help of several other people. I want to thank the co-author of this paper, Jared Smolens, for his very valuable contributions and our highly inspiring discussions. I'm also indebted to Thomas Nau (Ulm University, Germany), Shane Sigler and Mark Woodyard (both at Oracle) for their feedback on earlier versions of this paper. Karen Perkins (Perkins Technical Writing and Editing) and Rick Ramsey at Oracle were very helpful in providing editorial and publishing assistance.

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• How can a solo programmer become a good team player?

  - by Nick

  I've been programming (obsessively) since I was 12. I am fairly knowledgeable across the spectrum of languages out there, from assembly, to C++, to Javascript, to Haskell, Lisp, and Qi. But all of my projects have been by myself. I got my degree in chemical engineering, not CS or computer engineering, but for the first time this fall I'll be working on a large programming project with other people, and I have no clue how to prepare. I've been using Windows all of my life, but this project is going to be very unix-y, so I purchased a Mac recently in the hopes of familiarizing myself with the environment. I was fortunate to participate in a hackathon with some friends this past year -- both CS majors -- and excitingly enough, we won. But I realized as I worked with them that their workflow was very different from mine. They used Git for version control. I had never used it at the time, but I've since learned all that I can about it. They also used a lot of frameworks and libraries. I had to learn what Rails was pretty much overnight for the hackathon (on the other hand, they didn't know what lexical scoping or closures were). All of our code worked well, but they didn't understand mine, and I didn't understand theirs. I hear references to things that real programmers do on a daily basis -- unit testing, code reviews, but I only have the vaguest sense of what these are. I normally don't have many bugs in my little projects, so I have never needed a bug tracking system or tests for them. And the last thing is that it takes me a long time to understand other people's code. Variable naming conventions (that vary with each new language) are difficult (__mzkwpSomRidicAbbrev), and I find the loose coupling difficult. That's not to say I don't loosely couple things -- I think I'm quite good at it for my own work, but when I download something like the Linux kernel or the Chromium source code to look at it, I spend hours trying to figure out how all of these oddly named directories and files connect. It's a programming sin to reinvent the wheel, but I often find it's just quicker to write up the functionality myself than to spend hours dissecting some library. Obviously, people who do this for a living don't have these problems, and I'll need to get to that point myself. Question: What are some steps that I can take to begin "integrating" with everyone else? Thanks!

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• Perl syntax error [closed]

  - by Linny

  I am a beginner taking a Perl programming course. We are trying to write a basic program for counting nucleotides in a DNA string. I'm getting syntax errors on the lines that have a single bracket on lines 28 & 70 and don't know why. It also reads that I have compilation errors. I have no idea where to start figuring that out. # The purpose of this program is to count the number of nucleotides in a strand. Each protein is counted separately # print "/n NOTE: Nucleotide counting /n"; # use strict; # enforce variable declarations use warnings; # enable compiler warnings # Display number of A,a,T,t,G,g,C,c, nucleotides in a word or sequence of letters. # my ($base) = ''; # an extracted letter from a string my ($nuceotide_count) = 0 ; # the current position within the word my ($position) = 0 ; # number of vowels in user-supplied word my ($word) = ''; # word to be processed my ($A_count) = 0 ; # of A nucleotides in the user-supplied sequence my ($a_count) = 0 ; # of A nucleotides in the user-supplied sequence my ($C_count) = 0 ; # of C nucleotides in the user-supplied sequence my ($c_count) = 0 ; # of C nucleotides in the user-supplied sequence my ($G_count) = 0 ; # of G nucleotides in the user-supplied sequence my ($g_count) = 0 ; # of G nucleotides in the user-supplied sequence my ($T_count) = 0 ; # of T nucleotides in the user-supplied sequence my ($t_count) = 0 ; # of T nucleotides in the user-supplied sequence word = (STDIN) for ($position = 0);($position if (($base eq 'a') or ($base eq 'A')) { ++$A_count; } # end if ++$position; if (($base eq 'T') or ($base eq 't')) { ++$T_count; } end if ++$position; if (($base eq 'G') or ($base eq 'g')) { ++$G_count; } # end if ++$position; if (($base eq 'C') or ($base eq 'c')) { ++$C_count; } # end if ++$position; } # end for # Display final results. # print " \n The number of A or a neucleotides is: $A_count"; print " \n The number of T or t neucleotides is: $T_count"; print " \n The number of G or g neucleotides is: $G_count"; print " \n The number of C or c neucleotides is: $C_count"; print " \n\n Program completed successfully. \n" ; exit ;

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• A strong component keeps everything together

  - by Justin Paul-Oracle

  Most of the times you implement a WebCenter Content based system, you require some sort of customization. Sometimes these customizations need a Java class or two, or libraries (for example, the JavaMail API), or Database Objects (like new tables, views, indexes, etc). I have seen that libraries and Database Objects are usually put in place using manual steps. This means that the library jar files are copied to one of the common classes directory (set in the Content CLASSPATH variable) and/or the database scripts are executed manually. I have also seen people place the custom Java classes in the common classes directory. While this may seem like an easy solution, think about a scenario where you need to disable or uninstall the component or if you have to upgrade or migrate the system. You have to keep these manual steps documented and execute them every time you encounter the above scenarios. It is very common that some of these manual steps are missed when you have multiple teams and people working on the system. Here are a few points to ponder upon: Place all your custom Java classes within your component. Create a new directory, say ${COMPONENT_DIR}/classes, and place your code there. You can choose to bundle all your classes into a jar or you can place the entire class directory structure. Add a path entry to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path and the Custom Class Path Load Order under the Advanced Build Settings. This will ensure that the system CLASSPATH is updated to add this new directory. Create a new component for any new library that you want to add. Add the appropriate path entries to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path, Custom Class Path Load Order and/or the Custom Library Path under the Advanced Build Settings. Enter a comma separated list of features that this component will provide. When you create other components that will use the features exposed by this component, make sure that you specify a dependency to this library component by specifying the comma separated list of features in the Advanced Build Settings. The component wizard allows you to create custom install/uninstall Java code. The wizard will create a install filter class when you check the “Has Install” checkbox on the “Install/Uninstall Settings” tab. Consider using this filter class to create database objects when you install the component and drop the objects when you uninstall the component. If you do a lot of custom component development, consider creating a install/uninstall Java class, which can execute queries defined within the component. To sum up, whenever you write a new custom component, make sure that you bundle everything within the component.

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• Memory read/write access efficiency

  - by wolfPack88

  I've heard conflicting information from different sources, and I'm not really sure which one to believe. As such, I'll post what I understand and ask for corrections. Let's say I want to use a 2D matrix. There are three ways that I can do this (at least that I know of). 1: int i; char **matrix; matrix = malloc(50 * sizeof(char *)); for(i = 0; i < 50; i++) matrix[i] = malloc(50); 2: int i; int rowSize = 50; int pointerSize = 50 * sizeof(char *); int dataSize = 50 * 50; char **matrix; matrix = malloc(dataSize + pointerSize); char *pData = matrix + pointerSize - rowSize; for(i = 0; i < 50; i++) { pData += rowSize; matrix[i] = pData; } 3: //instead of accessing matrix[i][j] here, we would access matrix[i * 50 + j] char *matrix = malloc(50 * 50); In terms of memory usage, my understanding is that 3 is the most efficient, 2 is next, and 1 is least efficient, for the reasons below: 3: There is only one pointer and one allocation, and therefore, minimal overhead. 2: Once again, there is only one allocation, but there are now 51 pointers. This means there is 50 * sizeof(char *) more overhead. 1: There are 51 allocations and 51 pointers, causing the most overhead of all options. In terms of performance, once again my understanding is that 3 is the most efficient, 2 is next, and 1 is least efficient. Reasons being: 3: Only one memory access is needed. We will have to do a multiplication and an addition as opposed to two additions (as in the case of a pointer to a pointer), but memory access is slow enough that this doesn't matter. 2: We need two memory accesses; once to get a char *, and then to the appropriate char. Only two additions are performed here (once to get to the correct char * pointer from the original memory location, and once to get to the correct char variable from wherever the char * points to), so multiplication (which is slower than addition) is not required. However, on modern CPUs, multiplication is faster than memory access, so this point is moot. 1: Same issues as 2, but now the memory isn't contiguous. This causes cache misses and extra page table lookups, making it the least efficient of the lot. First and foremost: Is this correct? Second: Is there an option 4 that I am missing that would be even more efficient?

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• Calculating for leap year [migrated]

  - by Bradley Bauer

  I've written this program using Java in Eclipse. I was able to utilize a formula I found that I explained in the commented out section. Using the for loop I can iterate through each month of the year, which I feel good about in that code, it seems clean and smooth to me. Maybe I could give the variables full names to make everything more readable but I'm just using the formula in its basic essence :) Well my problem is it doesn't calculate correctly for years like 2008... Leap Years. I know that if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) then we have a leap year. Maybe if the year is a leap year I need to subtract a certain amount of days from a certain month. Any solutions, or some direction would be great thanks :) package exercises; public class E28 { /* * Display the first days of each month * Enter the year * Enter first day of the year * * h = (q + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5j) % 7 * * h is the day of the week (0: Saturday, 1: Sunday ......) * q is the day of the month * m is the month (3: March 4: April.... January and Feburary are 13 and 14) * j is the century (year / 100) * k is the year of the century (year %100) * */ public static void main(String[] args) { java.util.Scanner input = new java.util.Scanner(System.in); System.out.print("Enter the year: "); int year = input.nextInt(); int j = year / 100; // Find century for formula int k = year % 100; // Find year of century for formula // Loop iterates 12 times. Guess why. for (int i = 1, m = i; i <= 12; i++) { // Make m = i. So loop processes formula once for each month if (m == 1 || m == 2) m += 12; // Formula requires that Jan and Feb are represented as 13 and 14 else m = i; // if not jan or feb, then set m to i int h = (1 + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5 * j) % 7; // Formula created by a really smart man somewhere // I let the control variable i steer the direction of the formual's m value String day; if (h == 0) day = "Saturday"; else if (h == 1) day = "Sunday"; else if (h == 2) day = "Monday"; else if (h == 3) day = "Tuesday"; else if (h == 4) day = "Wednesday"; else if (h == 5) day = "Thursday"; else day = "Friday"; switch (m) { case 13: System.out.println("January 1, " + year + " is " + day); break; case 14: System.out.println("Feburary 1, " + year + " is " + day); break; case 3: System.out.println("March 1, " + year + " is " + day); break; case 4: System.out.println("April 1, " + year + " is " + day); break; case 5: System.out.println("May 1, " + year + " is " + day); break; case 6: System.out.println("June 1, " + year + " is " + day); break; case 7: System.out.println("July 1, " + year + " is " + day); break; case 8: System.out.println("August 1, " + year + " is " + day); break; case 9: System.out.println("September 1, " + year + " is " + day); break; case 10: System.out.println("October 1, " + year + " is " + day); break; case 11: System.out.println("November 1, " + year + " is " + day); break; case 12: System.out.println("December 1, " + year + " is " + day); break; } } } }

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• Is there a pedagogical game engine?

  - by K.G.

  I'm looking for a book, website, or other resource that gives modern 3D game engines the same treatment as Operating Systems: Design and Implementation gave operating systems. I have read Jason Gregory's Game Engine Architecture, which I enjoyed. However, by intent the author treated components of the architecture as atomic units, whereas what I'm interested in is the plumbing between those units that makes a coherent whole out of ideally loosely coupled parts. In books such as these, one usually reads that "that's academic," but that's the point! I have also read Julian Gold's Object-oriented Game Development, which likewise was good, but I feel is beginning to show its age. Since even mobile platforms these days are multicore and have fast video memory, those kinds of things (concurrency, display item buffering) would ideally be covered. There are other resources, such as the Doom 3 source code, which is highly instructive for its being a shipped product. The problem with those is as follows: float Q_rsqrt( float number ) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; // evil floating point bit level hacking i = 0x5f3759df - ( i >> 1 ); // what the f***? y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration // y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed return y; } To wit, while brilliant, this kind of source requires more enlightenment than I can usually muster upon first read. In summary, here's my white whale: For an adult reader with experience in programming. I wish I could save all the trees killed by every. Single. Game Programming book ever devoting the first two chapters to "Now just what is a variable anyway?" In C or C++, very preferably C++. Languages that are more concise are fantastic for teaching, except for when what you want to learn is how to cope with a verbose language. There is also the benefit of the guardrails that C++ doesn't provide, such as garbage collection. Platform agnostic. I'm sincerely afraid that this book is out there and it's Visual C++/DirectX oriented. I'm a Linux guy, and I'd do what it takes, but I would very much like to be able to use OpenGL. Thanks for everything! Before anyone gets on my case about it, Fast inverse square root was from Quake III Arena, not Doom 3!

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