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  • ANTS CLR and Memory Profiler In Depth Review (Part 1 of 2 &ndash; CLR Profiler)

    - by ToStringTheory
    One of the things that people might not know about me, is my obsession to make my code as efficient as possible.  Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind…  In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve.  One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well.  In this review, I am going to cover some of the features of the ANTS profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program.  I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction The ANTS Profiler pack provided by Red Gate was something that I had not heard of before receiving an email regarding an offer to review it for a license.  Since I look to make my code efficient, it was a no brainer for me to try it out!  One thing that I have to say took me by surprise is that upon downloading the program and installing it you fill out a form for your usual contact information.  Sure enough within 2 hours, I received an email from a sales representative at Red Gate asking if she could help me to achieve the most out of my trial time so it wouldn’t go to waste.  After replying to her and explaining that I was looking to review its feature set, she put me in contact with someone that setup a demo session to give me a quick rundown of its features via an online meeting.  After having dealt with a massive ordeal with one of my utility companies and their complete lack of customer service, Red Gates friendly and helpful representatives were a breath of fresh air, and something I was thankful for. ANTS CLR Profiler The ANTS CLR profiler is the thing I want to focus on the most in this post, so I am going to dive right in now. Install was simple and took no time at all.  It installed both the profiler for the CLR and Memory, but also visual studio extensions to facilitate the usage of the profilers (click any images for full size images): The Visual Studio menu options (under ANTS menu) Starting the CLR Performance Profiler from the start menu yields this window If you follow the instructions after launching the program from the start menu (Click File > New Profiling Session to start a new project), you are given a dialog with plenty of options for profiling: The New Session dialog.  Lots of options.  One thing I noticed is that the buttons in the lower right were half-covered by the panel of the application.  If I had to guess, I would imagine that this is caused by my DPI settings being set to 125%.  This is a problem I have seen in other applications as well that don’t scale well to different dpi scales. The profiler options give you the ability to profile: .NET Executable ASP.NET web application (hosted in IIS) ASP.NET web application (hosted in IIS express) ASP.NET web application (hosted in Cassini Web Development Server) SharePoint web application (hosted in IIS) Silverlight 4+ application Windows Service COM+ server XBAP (local XAML browser application) Attach to an already running .NET 4 process Choosing each option provides a varying set of other variables/options that one can set including options such as application arguments, operating path, record I/O performance performance counters to record (43 counters in all!), etc…  All in all, they give you the ability to profile many different .Net project types, and make it simple to do so.  In most cases of my using this application, I would be using the built in Visual Studio extensions, as they automatically start a new profiling project in ANTS with the options setup, and start your program, however RedGate has made it easy enough to profile outside of Visual Studio as well. On the flip side of this, as someone who lives most of their work life in Visual Studio, one thing I do wish is that instead of opening an entirely separate application/gui to perform profiling after launching, that instead they would provide a Visual Studio panel with the information, and integrate more of the profiling project information into Visual Studio.  So, now that we have an idea of what options that the profiler gives us, its time to test its abilities and features. Horrendous Example Code – Prime Number Generator One of my interests besides development, is Physics and Math – what I went to college for.  I have especially always been interested in prime numbers, as they are something of a mystery…  So, I decided that I would go ahead and to test the abilities of the profiler, I would write a small program, website, and library to generate prime numbers in the quantity that you ask for.  I am going to start off with some terrible code, and show how I would see the profiler being used as a development tool. First off, the IPrimes interface (all code is downloadable at the end of the post): interface IPrimes { IEnumerable<int> GetPrimes(int retrieve); } Simple enough, right?  Anything that implements the interface will (hopefully) provide an IEnumerable of int, with the quantity specified in the parameter argument.  Next, I am going to implement this interface in the most basic way: public class DumbPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _analyzing = 4; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; //start dividing at 2 //divide until number is reached, or determined not prime for (int i = 2; i < _analyzing && isPrime; i++) { //if (i) goes into _analyzing without a remainder, //_analyzing is NOT prime if (_analyzing % i == 0) isPrime = false; } //if it is prime, add to found list if (isPrime) _foundPrimes.Add(_analyzing); //increment number to analyze next _analyzing++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } This is the simplest way to get primes in my opinion.  Checking each number by the straight definition of a prime – is it divisible by anything besides 1 and itself. I have included this code in a base class library for my solution, as I am going to use it to demonstrate a couple of features of ANTS.  This class library is consumed by a simple non-MVVM WPF application, and a simple MVC4 website.  I will not post the WPF code here inline, as it is simply an ObservableCollection<int>, a label, two textbox’s, and a button. Starting a new Profiling Session So, in Visual Studio, I have just completed my first stint developing the GUI and DumbPrimes IPrimes class, so now I want to check my codes efficiency by profiling it.  All I have to do is build the solution (surprised initiating a profiling session doesn’t do this, but I suppose I can understand it), and then click the ANTS menu, followed by Profile Performance.  I am then greeted by the profiler starting up and already monitoring my program live: You are provided with a realtime graph at the top, and a pane at the bottom giving you information on how to proceed.  I am going to start by asking my program to show me the first 15000 primes: After the program finally began responding again (I did all the work on the main UI thread – how bad!), I stopped the profiler, which did kill the process of my program too.  One important thing to note, is that the profiler by default wants to give you a lot of detail about the operation – line hit counts, time per line, percent time per line, etc…  The important thing to remember is that this itself takes a lot of time.  When running my program without the profiler attached, it can generate the 15000 primes in 5.18 seconds, compared to 74.5 seconds – almost a 1500 percent increase.  While this may seem like a lot, remember that there is a trade off.  It may be WAY more inefficient, however, I am able to drill down and make improvements to specific problem areas, and then decrease execution time all around. Analyzing the Profiling Session After clicking ‘Stop Profiling’, the process running my application stopped, and the entire execution time was automatically selected by ANTS, and the results shown below: Now there are a number of interesting things going on here, I am going to cover each in a section of its own: Real Time Performance Counter Bar (top of screen) At the top of the screen, is the real time performance bar.  As your application is running, this will constantly update with the currently selected performance counters status.  A couple of cool things to note are the fact that you can drag a selection around specific time periods to drill down the detail views in the lower 2 panels to information pertaining to only that period. After selecting a time period, you can bookmark a section and name it, so that it is easy to find later, or after reloaded at a later time.  You can also zoom in, out, or fit the graph to the space provided – useful for drilling down. It may be hard to see, but at the top of the processor time graph below the time ticks, but above the red usage graph, there is a green bar. This bar shows at what times a method that is selected in the ‘Call tree’ panel is called. Very cool to be able to click on a method and see at what times it made an impact. As I said before, ANTS provides 43 different performance counters you can hook into.  Click the arrow next to the Performance tab at the top will allow you to change between different counters if you have them selected: Method Call Tree, ADO.Net Database Calls, File IO – Detail Panel Red Gate really hit the mark here I think. When you select a section of the run with the graph, the call tree populates to fill a hierarchical tree of method calls, with information regarding each of the methods.   By default, methods are hidden where the source is not provided (framework type code), however, Red Gate has integrated Reflector into ANTS, so even if you don’t have source for something, you can select a method and get the source if you want.  Methods are also hidden where the impact is seen as insignificant – methods that are only executed for 1% of the time of the overall calling methods time; in other words, working on making them better is not where your efforts should be focused. – Smart! Source Panel – Detail Panel The source panel is where you can see line level information on your code, showing the code for the currently selected method from the Method Call Tree.  If the code is not available, Reflector takes care of it and shows the code anyways! As you can notice, there does seem to be a problem with how ANTS determines what line is the actual line that a call is completed on.  I have suspicions that this may be due to some of the inline code optimizations that the CLR applies upon compilation of the assembly.  In a method with comments, the problem is much more severe: As you can see here, apparently the most offending code in my base library was a comment – *gasp*!  Removing the comments does help quite a bit, however I hope that Red Gate works on their counter algorithm soon to improve the logic on positioning for statistics: I did a small test just to demonstrate the lines are correct without comments. For me, it isn’t a deal breaker, as I can usually determine the correct placements by looking at the application code in the region and determining what makes sense, but it is something that would probably build up some irritation with time. Feature – Suggest Method for Optimization A neat feature to really help those in need of a pointer, is the menu option under tools to automatically suggest methods to optimize/improve: Nice feature – clicking it filters the call tree and stars methods that it thinks are good candidates for optimization.  I do wish that they would have made it more visible for those of use who aren’t great on sight: Process Integration I do think that this could have a place in my process.  After experimenting with the profiler, I do think it would be a great benefit to do some development, testing, and then after all the bugs are worked out, use the profiler to check on things to make sure nothing seems like it is hogging more than its fair share.  For example, with this program, I would have developed it, ran it, tested it – it works, but slowly. After looking at the profiler, and seeing the massive amount of time spent in 1 method, I might go ahead and try to re-implement IPrimes (I actually would probably rewrite the offending code, but so that I can distribute both sets of code easily, I’m just going to make another implementation of IPrimes).  Using two pieces of knowledge about prime numbers can make this method MUCH more efficient – prime numbers fall into two buckets 6k+/-1 , and a number is prime if it is not divisible by any other primes before it: public class SmartPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _k = 1; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; int potentialPrime; //analyze 6k-1 //assign the value to potential potentialPrime = 6 * _k - 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); if (_foundPrimes.Count() == retrieve) break; //analyze 6k+1 //assign the value to potential potentialPrime = 6 * _k + 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); //increment k to analyze next _k++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } Now there are definitely more things I can do to help make this more efficient, but for the scope of this example, I think this is fine (but still hideous)! Profiling this now yields a happy surprise 27 seconds to generate the 15000 primes with the profiler attached, and only 1.43 seconds without.  One important thing I wanted to call out though was the performance graph now: Notice anything odd?  The %Processor time is above 100%.  This is because there is now more than 1 core in the operation.  A better label for the chart in my mind would have been %Core time, but to each their own. Another odd thing I noticed was that the profiler seemed to be spot on this time in my DumbPrimes class with line details in source, even with comments..  Odd. Profiling Web Applications The last thing that I wanted to cover, that means a lot to me as a web developer, is the great amount of work that Red Gate put into the profiler when profiling web applications.  In my solution, I have a simple MVC4 application setup with 1 page, a single input form, that will output prime values as my WPF app did.  Launching the profiler from Visual Studio as before, nothing is really different in the profiler window, however I did receive a UAC prompt for a Red Gate helper app to integrate with the web server without notification. After requesting 500, 1000, 2000, and 5000 primes, and looking at the profiler session, things are slightly different from before: As you can see, there are 4 spikes of activity in the processor time graph, but there is also something new in the call tree: That’s right – ANTS will actually group method calls by get/post operations, so it is easier to find out what action/page is giving the largest problems…  Pretty cool in my mind! Overview Overall, I think that Red Gate ANTS CLR Profiler has a lot to offer, however I think it also has a long ways to go.  3 Biggest Pros: Ability to easily drill down from time graph, to method calls, to source code Wide variety of counters to choose from when profiling your application Excellent integration/grouping of methods being called from web applications by request – BRILLIANT! 3 Biggest Cons: Issue regarding line details in source view Nit pick – Processor time vs. Core time Nit pick – Lack of full integration with Visual Studio Ratings Ease of Use (7/10) – I marked down here because of the problems with the line level details and the extra work that that entails, and the lack of better integration with Visual Studio. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Especially with its large variety of performance counters, a definite plus! Features (9/10) – Besides the real time performance monitoring, and the drill downs that I’ve shown here, ANTS also has great integration with ADO.Net, with the ability to show database queries run by your application in the profiler.  This, with the line level details, the web request grouping, reflector integration, and various options to customize your profiling session I think create a great set of features! Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (8/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (8/10) – Overall, I am happy with the Performance Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  I WOULD recommend you trying the application and seeing if it would fit into your process, BUT, remember there are still some kinks in it to hopefully be worked out. My next post will definitely be shorter (hopefully), but thank you for reading up to here, or skipping ahead!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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  • How to test a 3D rendering engine?

    - by YoYo
    Me and some friends developing simple 3D rendering engine as practice for the university. We used Ogre 3d as prototype and now we are developing it from base The engine is wrapped up in simple game that asks the user to select shape (circle, triangle, square...), color and dimensions and renders the image to the screen. It also enables to move and rotate the shape on screen using mouse. We would like to test automate the view rendering. I could not find any test framework for this issue and I would like to know how 3D test is done in non manual matter

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  • Using TPL and PLINQ to raise performance of feed aggregator

    - by DigiMortal
    In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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  • Using Stub Objects

    - by user9154181
    Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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  • 3D collision detection with meshes using only raycasting?

    - by Nick
    I'm building a game using WebGL and Three.js, and so far I have a terrain with a guy walking on it. I simply cast a ray downwards to know the terrain height. How can I do this for other 3D objects, like the inside of a house? Is this possible by casting many rays in every direction of the player? If not, I would like to know how I can achieve the simplest collision detection possible for other meshes. Do you have to cast a ray to every triangle in every mesh nearby?

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  • Cannot install shell-themes using gnome-tweak-tool

    - by Chris
    How do I fix this? I will attempt to upload a screenshot of the problem. Notice there is an error like triangle near the shell themes and nothing is select-able. Also there are no shell extensions under the shell extensions tab. I have come across many postings on how to fix this but none worked for me. I currently have 12.04 LTS. I have a custom Phenom quad core machine with Radeon HD 5770 graphics if that helps.

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  • Calculating adjacent quads on a quad sphere

    - by Caius Eugene
    I've been experimenting with generating a quad sphere. This sphere subdivides into a quadtree structure. Eventually I'm going to be applying some simplex noise to the vertices of each face to create a terrain like surface. To solve the issue of cracks I want to be able to apply a geomitmap technique of triangle fanning on the edges of each quad, but in order to know the subdivision level of the adjacent quads I need to identify which quads are adjacent to each other. Does anyone know any approaches to computing and storing these adjacent quads for quick lookup? Also It's important that I know which direction they are in so I can easily adjust the correct edge.

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  • Network Manager Applet menu freezes and does not respond

    - by pst007x
    Since the latest update in Ubuntu 10.10, the nm-applet has started doing some strange things. I boot up the PC, all is fine, internet works, etc... but after a period of time, approx and hour, the nm-applet menu in the Gnome panel fails to respond. when I click on the icon, the menu appears, all looks well, but when I select any option, eg DISCONNECT, nothing happens. Even the VPN sub menu disappears (no triangle to select the menu.) However I do not lose the network connection... If I Run this script: killall nm-applet /etc/init.d/NetworkManager restart nm-applet all returns as normal, for a while... weird? i tried uninstall/reinstall... I even reinstalled Ubuntu, but once the latest updates are applied this issues arises... Any help?

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  • Transparency in XNA-4 primitives

    - by Shashwat
    I'm using XNA 4 with Visual Studio 2010. I'm trying to create a simple 3D world with walls and doors in which the user to free to roam around. A wall is just a rectangle which is currently being rendered with four vertices using triangle strips. But to create a door, I'd have to split it into three rectangles as shown in the figure. Four quadrilaterals if I want to have the following door-style It will become more complex to have multiple doors on the same wall or if I have windows. Is there any shorter way to handle this? I am looking for something that will just make the wall transparent wherever I want. I found a solution but facing a problem here

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  • Where can I find Cinema4D for game development tutorials ?

    - by George Profenza
    Hi, I started to learn Cinema 4D. I've noticed it's really easy to use for motion graphics, but I want to use it for modeling for games/realtime 3d engines. Before I used 3dsmax and it was easy to estimate how a model would look/behave in a 3d engine. The two main things I did was displaying Polygon triangles and displaying the Polygon Count. I've found the Total Polygons tick in HUD settings in Cinema 4D, but I can't find any display mode that will show triangles. Is there there a way to display triangle faces/not quads in Cinema4D ? If so how ? There is a Triangulate function, but I'd rather not Triangulate/Untriangulate all the time, especially since it's converting back and forth between the two doesn't always produce the same result. I imagine I'm asking for old school techniques, but I plan to use these to make low poly models for web(canvas/webGL) and mobile.

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  • Radiosity using a hemisphere

    - by P. Avery
    I'm working on a radiosity processor. I'm projecting scene geometry onto a hemisphere at a high order of tessellation during a visibility pass onto a 1024x1024 render target. The problem is that the edges of certain triangles are not being rendered to the item buffer( render target )...so when I test certain edges( or pixels during pixel shader ) for visibility during a reconstruction pass, visible edges are not identified and as a result the pixel for that edge is discarded. One solution was to increase the resolution of the item buffer( up to 4096x4096 )...this helped and more edges were visible, however, this was not fullproof. How do I increase visibility? Here is a screenshot of a scene after radiosity is applied: the seams are edges along a triangle face that were not visible due to the resolution of the item buffer... fixed the problem by sampling the item buffer w/8 points:

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  • Multiple Vertex Buffers per Mesh

    - by Daniel
    I've run into the situation where the size of my mesh with all its vertices and indices, is larger than the (optimal) vertex buffer object upper limit (~8MB). I was wondering if I can sub-divide the mesh across multiple vertex buffers, and somehow retain validity of the indices. Ie a triangle with a indice at the first vertex, and an indice at the last (ie in seperate VBOs). All the while maintaining this within Vertex Array Objects. My thoughts are, save myself the hassle, and for meshes (messes :P) such as this, just use the necessary size ( 8MB); which is what I do at the moment. But ideally my buffer manager (wip) at the moment is using optimal sizes; I may just have to make a special case then... Any ideas? If necessary, a simple C++ code example is appreciated. Note: I have also cross-posted this on stackoverflow, as I was not sure as to which it would be more suitable (its partly a design question).

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  • Annoying flickering of vertices and edges (possible z-fighting)

    - by Belgin
    I'm trying to make a software z-buffer implementation, however, after I generate the z-buffer and proceed with the vertex culling, I get pretty severe discrepancies between the vertex depth and the depth of the buffer at their projected coordinates on the screen (i.e. zbuffer[v.xp][v.yp] != v.z, where xp and yp are the projected x and y coordinates of the vertex v), sometimes by a small fraction of a unit and sometimes by 2 or 3 units. Here's what I think is happening: Each triangle's data structure holds the plane's (that is defined by the triangle) coefficients (a, b, c, d) computed from its three vertices from their normal: void computeNormal(Vertex *v1, Vertex *v2, Vertex *v3, double *a, double *b, double *c) { double a1 = v1 -> x - v2 -> x; double a2 = v1 -> y - v2 -> y; double a3 = v1 -> z - v2 -> z; double b1 = v3 -> x - v2 -> x; double b2 = v3 -> y - v2 -> y; double b3 = v3 -> z - v2 -> z; *a = a2*b3 - a3*b2; *b = -(a1*b3 - a3*b1); *c = a1*b2 - a2*b1; } void computePlane(Poly *p) { double x = p -> verts[0] -> x; double y = p -> verts[0] -> y; double z = p -> verts[0] -> z; computeNormal(p -> verts[0], p -> verts[1], p -> verts[2], &p -> a, &p -> b, &p -> c); p -> d = p -> a * x + p -> b * y + p -> c * z; } The z-buffer just holds the smallest depth at the respective xy coordinate by somewhat casting rays to the polygon (I haven't quite got interpolation right yet so I'm using this slower method until I do) and determining the z coordinate from the reversed perspective projection formulas (which I got from here: double z = -(b*Ez*y + a*Ez*x - d*Ez)/(b*y + a*x + c*Ez - b*Ey - a*Ex); Where x and y are the pixel's coordinates on the screen; a, b, c, and d are the planes coefficients; Ex, Ey, and Ez are the eye's (camera's) coordinates. This last formula does not accurately give the exact vertices' z coordinate at their projected x and y coordinates on the screen, probably because of some floating point inaccuracy (i.e. I've seen it return something like 3.001 when the vertex's z-coordinate was actually 2.998). Here is the portion of code that hides the vertices that shouldn't be visible: for(i = 0; i < shape.nverts; ++i) { double dist = shape.verts[i].z; if(z_buffer[shape.verts[i].yp][shape.verts[i].xp].z < dist) shape.verts[i].visible = 0; else shape.verts[i].visible = 1; } How do I solve this issue? EDIT I've implemented the near and far planes of the frustum, with 24 bit accuracy, and now I have some questions: Is this what I have to do this in order to resolve the flickering? When I compare the z value of the vertex with the z value in the buffer, do I have to convert the z value of the vertex to z' using the formula, or do I convert the value in the buffer back to the original z, and how do I do that? What are some decent values for near and far? Thanks in advance.

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  • how to generate number pattern in triangular form

    - by Vignesh Vicky
    I want to print this pattern like right angled triangle 0 909 89098 7890987 678909876 56789098765 4567890987654 345678909876543 23456789098765432 1234567890987654321 I wrote following code # include<stdio.h> # include<conio.h> void main() { clrscr(); int i,j,x,z,k,f=1; for ( i=10;i>=1;i--,f++) { for(j=1;j<=f;j++,k--) { k=i; if(k!=10) { printf("%d",k); } if(k==10) { printf("0"); } } for(x=1;x<f;x++,z--) { z=9; printf("%d",z); } printf("%d/n"); } getch(); } what is wrong with this code? when i check manually it seems correct but when compiled gives different pattern

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  • Can I animate render targets or the swap chain?

    - by Eric F.
    I want to animate some synthetic video bits to fullscreen w/o tearing. Can I set up D3D 9/10/11 in exclusive mode, and have it present a series of buffers that I'm writing to? I know how to copy system memory bits into a texture, then draw that texture as a fullscreen quad, but it seems like overkill. Why should I use the triangle rasterizer when I want to do something so simple? All I want to do is set up a long (4-8 buffer) swapchain and set the bits of the back buffer that is about to be displayed. Or, I want to allocate 4-8 RenderTargets, and on each frame, copy the bits from system memory to the RenderTarget, then set it as the next thing to display. I've never seen or heard about anybody doing this, but it seems so dead simple!

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  • Calculating vertex normals on the GPU

    - by Etan
    I have some height-map sampled on a regular grid stored in an array. Now, I want to use the normals on the sampled vertices for some smoothing algorithm. The way I'm currently doing it is as follows: For each vertex, generate triangles to all it's neighbours. This results in eight neighbours when using the 1-neighbourhood for all vertices except at the borders. +---+---+ ¦ \ ¦ / ¦ +---o---+ ¦ / ¦ \ ¦ +---+---+ For each adjacent triangle, calculate it's normal by taking the cross product between the two distances. As the triangles all have the same size when projected on the xy-plane, I simply average over all eight normals then and store it for this vertex. However, as my data grows larger, this approach takes too much time and I would prefer doing it on the GPU in a shader code. Is there an easy method, maybe if I could store my height-map as a texture?

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  • Where is Nautilus icon file located and how is it chosen?

    - by Steve
    When I plug my Garmin Nuvi 265 GPS device into my computer via a USB cable, it mounts as a drive with a blue triangle icon instead of the default gray hard drive icon. HOW does Nautilus know how to do this? After much laborious searching, I found that the icon info is stored in ~/.gconf/apps/nautilus/desktop-metadata/GARMIN@46@volume/gconf.xml -- but only when a custom icon is selected. So Where is this blue icon file? Why does Nautilus use it instead of the plain drive icon? Is there a way to have give each of my drives a custom icon -- so that when I stick in my various flash drives, they have a distinctive icon (i.e. a 'favicon.ico' file on root or such?) Using Gnome 2.30.2 on Ubuntu 10.04.

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  • How do I pass vertex and color positions to OpenGL shaders?

    - by smoth190
    I've been trying to get this to work for the past two days, telling myself I wouldn't ask for help. I think you can see where that got me... I thought I'd try my hand at a little OpenGL, because DirectX is complex and depressing. I picked OpenGL 3.x, because even with my OpenGL 4 graphics card, all my friends don't have that, and I like to let them use my programs. There aren't really any great tutorials for OpenGL 3, most are just "type this and this will happen--the end". I'm trying to just draw a simple triangle, and so far, all I have is a blank screen with my clear color (when I set the draw type to GL_POINTS I just get a black dot). I have no idea what the problem is, so I'll just slap down the code: Here is the function that creates the triangle: void CEntityRenderable::CreateBuffers() { m_vertices = new Vertex3D[3]; m_vertexCount = 3; m_vertices[0].x = -1.0f; m_vertices[0].y = -1.0f; m_vertices[0].z = -5.0f; m_vertices[0].r = 1.0f; m_vertices[0].g = 0.0f; m_vertices[0].b = 0.0f; m_vertices[0].a = 1.0f; m_vertices[1].x = 1.0f; m_vertices[1].y = -1.0f; m_vertices[1].z = -5.0f; m_vertices[1].r = 1.0f; m_vertices[1].g = 0.0f; m_vertices[1].b = 0.0f; m_vertices[1].a = 1.0f; m_vertices[2].x = 0.0f; m_vertices[2].y = 1.0f; m_vertices[2].z = -5.0f; m_vertices[2].r = 1.0f; m_vertices[2].g = 0.0f; m_vertices[2].b = 0.0f; m_vertices[2].a = 1.0f; //Create the VAO glGenVertexArrays(1, &m_vaoID); //Bind the VAO glBindVertexArray(m_vaoID); //Create a vertex buffer glGenBuffers(1, &m_vboID); //Bind the buffer glBindBuffer(GL_ARRAY_BUFFER, m_vboID); //Set the buffers data glBufferData(GL_ARRAY_BUFFER, sizeof(m_vertices), m_vertices, GL_STATIC_DRAW); //Set its usage glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex3D), 0); glVertexAttribPointer(1, 4, GL_FLOAT, GL_TRUE, sizeof(Vertex3D), (void*)(3*sizeof(float))); //Enable glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); //Check for errors if(glGetError() != GL_NO_ERROR) { Error("Failed to create VBO: %s", gluErrorString(glGetError())); } //Unbind... glBindVertexArray(0); } The Vertex3D struct is as such... struct Vertex3D { Vertex3D() : x(0), y(0), z(0), r(0), g(0), b(0), a(1) {} float x, y, z; float r, g, b, a; }; And finally the render function: void CEntityRenderable::RenderEntity() { //Render... glBindVertexArray(m_vaoID); //Use our attribs glDrawArrays(GL_POINTS, 0, m_vertexCount); glBindVertexArray(0); //unbind OnRender(); } (And yes, I am binding and unbinding the shader. That is just in a different place) I think my problem is that I haven't fully wrapped my mind around this whole VertexAttribArray thing (the only thing I like better in DirectX was input layouts D:). This is my vertex shader: #version 330 //Matrices uniform mat4 projectionMatrix; uniform mat4 viewMatrix; uniform mat4 modelMatrix; //In values layout(location = 0) in vec3 position; layout(location = 1) in vec3 color; //Out values out vec3 frag_color; //Main shader void main(void) { //Position in world gl_Position = vec4(position, 1.0); //gl_Position = projectionMatrix * viewMatrix * modelMatrix * vec4(in_Position, 1.0); //No color changes frag_color = color; } As you can see, I've disable the matrices, because that just makes debugging this thing so much harder. I tried to debug using glslDevil, but my program just crashes right before the shaders are created... so I gave up with that. This is my first shot at OpenGL since the good old days of LWJGL, but that was when I didn't even know what a shader was. Thanks for your help :)

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  • Gnome 3 Shell extensions not working on Ubuntu 12.4 [closed]

    - by user63960
    Possible Duplicate: Gnome Shell Extension Empty I just upgraded to Ubuntu 12.4 running on a Win 7 box via VBox and switched the user interface to Gnome 3 but have a problem. In Advanced Settings (gnome tweak), the Shell Extensions window has no listings and the Theme window shows a "caution" triangle next to the Shell theme drop box. I have re-installed the default extensions using the Noobs Lab posted instructions: sudo apt-get install shell-extensions3.4 sudo apt-get install gnome-shell-extensions The commands appear to complete without error. Symptoms are: Gnome 2 visual appearance and no window borders or controls. To close a window, I have to click the window indicator in the sys tray and select the close menu item. Any ideas?

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  • Per fragment lighting with OpenGL 4.x tessellated model

    - by Finlaybob
    I'm experienced with OpenGL 3+. I'm dabbling with tessellation shaders and have now got to a point where I have a nicely tessellated teapot/plane demo (quick look here) As can be seen from the screenshots, the lighting is broken (though admittedly doesn't look too bad in the image) I've tried to add a normal map to the equation but it still doesn't come out right, I can calculate the normals, tangents and binormals per triangle in the geometry shader but still looks wrong. I think the question would be; How do I add per fragment lighting to a tessellated model? The teapot is 32 16-point patches, the plane is one single 16 point patch. The shaders are here, but they are a complete mess, so I don't blame anyone who cant make sense of them. But peruse at your leisure if you like. Also, if this question is more suited to be somewhere else i.e. Stack Overflow or the Programming stack please let me know.

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  • Is it only possible to display 64k vertices on the monitor with 16bit?

    - by Aufziehvogel
    I did the first 3D tutorial over at riemers.net and stumbled upon that my graphic card only supports Shader 2.0 (Reach profile in XNA) which means I can only use Int16 to store the indices (triangle to vertex). This means that I can only store 2^16 = 65536 vertices. Also I read on the internet that you should prefer 16-bit over 32-bit because not all hardware (like mine) does support 32-bit. Yet, I am wondering: Do really all game scenes get along with only so little vertices? I though already faces of people used a lot of polygons (which are made up of vertices?). It’s not relevant for me yet, but I am interested: Do game scenes use only 65536 vertices? Do you use some trade-off to display more (e.g. 64k in GPU buffer rest on RAM) Is there some method to get more into the GPU buffer? I already read on some other posts that there seems to be a limit of 64k per mesh too, so maybe you can compact stuff to meshes?

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  • Vertex data split into separate buffers or one one structure?

    - by kiba2
    Is it better to have all vertex data in one structure like this: class MyVertex { int x,y,z; int u,v; int normalx, normaly, normalz; } Or to have each component (location, normal, texture coordinates) in separate arrays/buffers? To me it always seemed logical to keep the data grouped together in one structure because they'd always be the same for each instance of a shared vertex and that seems to be true for things like character models (ex: the normal should be an average of adjacent normals for smooth lighting). One instance where this doesn't seem to work is other kinds of meshes like say a cube where the texture coordinates for each may be the same but that causes them to be different where the vertices are shared. Does everybody normally keep them separate? Won't this make them less space efficient if there needs to be an instance of texture coordinates and normals for each triangle vertex (They won't be indexed)? Can OpenGL even handle this mixing of indexed (for location) vs non-indexed buffers in the same VBO?

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  • Update information outdated, "Failed to fetch cdrom"

    - by user285603
    I have a warning triangle on the top of my screen. When I click on it, it says that my update information is outdated. When I type sudo apt-get update && sudo apt-get upgrade into a terminal, I get this message: W: Failed to fetch cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Release i386 (20140417)/dists/trusty/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs W: Failed to fetch cdrom://Ubuntu 14.04 LTS _Trusty Tahr_ - Release i386 (20140417)/dists/trusty/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs E: Some index files failed to download. They have been ignored, or old ones used instead. Any ideas?

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  • How to move a rectangle properly?

    - by bodycountPP
    I recently started to learn OpenGL. Right now I finished the first chapter of the "OpenGL SuperBible". There were two examples. The first had the complete code and showed how to draw a simple triangle. The second example is supposed to show how to move a rectangle using SpecialKeys. The only code provided for this example was the SpecialKeys method. I still tried to implement it but I had two problems. In the previous example I declared and instaciated vVerts in the SetupRC() method. Now as it is also used in the SpecialKeys() method, I moved the declaration and instantiation to the top of the code. Is this proper c++ practice? I copied the part where vertex positions are recalculated from the book, but I had to pick the vertices for the rectangle on my own. So now every time I press a key for the first time the rectangle's upper left vertex is moved to (-0,5:-0.5). This ok because of GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y But I also think that this is the reason why my rectangle is shifted in the beginning. After the first time a key was pressed everything works just fine. Here is my complete code I hope you can help me on those two points. GLBatch squareBatch; GLShaderManager shaderManager; //Load up a triangle GLfloat vVerts[] = {-0.5f,0.5f,0.0f, 0.5f,0.5f,0.0f, 0.5f,-0.5f,0.0f, -0.5f,-0.5f,0.0f}; //Window has changed size, or has just been created. //We need to use the window dimensions to set the viewport and the projection matrix. void ChangeSize(int w, int h) { glViewport(0,0,w,h); } //Called to draw the scene. void RenderScene(void) { //Clear the window with the current clearing color glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT); GLfloat vRed[] = {1.0f,0.0f,0.0f,1.0f}; shaderManager.UseStockShader(GLT_SHADER_IDENTITY,vRed); squareBatch.Draw(); //perform the buffer swap to display the back buffer glutSwapBuffers(); } //This function does any needed initialization on the rendering context. //This is the first opportunity to do any OpenGL related Tasks. void SetupRC() { //Blue Background glClearColor(0.0f,0.0f,1.0f,1.0f); shaderManager.InitializeStockShaders(); squareBatch.Begin(GL_QUADS,4); squareBatch.CopyVertexData3f(vVerts); squareBatch.End(); } //Respond to arrow keys by moving the camera frame of reference void SpecialKeys(int key,int x,int y) { GLfloat stepSize = 0.025f; GLfloat blockSize = 0.5f; GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y if(key == GLUT_KEY_UP) { blockY += stepSize; } if(key == GLUT_KEY_DOWN){blockY -= stepSize;} if(key == GLUT_KEY_LEFT){blockX -= stepSize;} if(key == GLUT_KEY_RIGHT){blockX += stepSize;} //Recalculate vertex positions vVerts[0] = blockX; vVerts[1] = blockY - blockSize*2; vVerts[3] = blockX + blockSize * 2; vVerts[4] = blockY - blockSize *2; vVerts[6] = blockX+blockSize*2; vVerts[7] = blockY; vVerts[9] = blockX; vVerts[10] = blockY; squareBatch.CopyVertexData3f(vVerts); glutPostRedisplay(); } //Main entry point for GLUT based programs int main(int argc, char** argv) { //Sets the working directory. Not really needed gltSetWorkingDirectory(argv[0]); //Passes along the command-line parameters and initializes the GLUT library. glutInit(&argc,argv); //Tells the GLUT library what type of display mode to use, when creating the window. //Double buffered window, RGBA-Color mode,depth-buffer as part of our display, stencil buffer also available glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH|GLUT_STENCIL); //Window size glutInitWindowSize(800,600); glutCreateWindow("MoveRect"); glutReshapeFunc(ChangeSize); glutDisplayFunc(RenderScene); glutSpecialFunc(SpecialKeys); //initialize GLEW library GLenum err = glewInit(); //Check that nothing goes wrong with the driver initialization before we try and do any rendering. if(GLEW_OK != err) { fprintf(stderr,"Glew Error: %s\n",glewGetErrorString); return 1; } SetupRC(); glutMainLoop(); return 0; }

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  • Can I make Launcher icons dark/dim unless app is running (then in color)?

    - by Greg
    To improve visibility of what Launcher-Applications I have running (instead of relying solely on that small right-facing triangle), is it possible to make Launcher-icons default to a black&white/dark/dim state? And then when a launcher-icon is clicked (or the super+# shortcut used) that icon would gain color and backlight signifying the app is running? If the Launcher icon's app is not running, it is dimmed out. If the icon's app is running, it is showing in color and backlit. I'd prefer an "inhouse" solution as opposed to having to install additional software, but I'm interested in hearing all options for if this is possible.

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