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  • Google I/O 2010 - Data pipelines with Google App Engine

    Google I/O 2010 - Data pipelines with Google App Engine Google I/O 2010 - Building high-throughput data pipelines with Google App Engine App Engine 301 Brett Slatkin This session will cover how to build, test, and maintain large-scale data pipelines on Google App Engine. It will cover maximizing efficiency, productionization, and how to deal with changing requirements. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 5 0 ratings Time: 01:01:52 More in Science & Technology

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  • ASSIMP in my program is much slower to import than ASSIMP view program

    - by Marco
    The problem is really simple: if I try to load with the function aiImportFileExWithProperties a big model in my software (around 200.000 vertices), it takes more than one minute. If I try to load the very same model with ASSIMP view, it takes 2 seconds. For this comparison, both my software and Assimp view are using the dll version of the library at 64 bit, compiled by myself (Assimp64.dll). This is the relevant piece of code in my software // default pp steps unsigned int ppsteps = aiProcess_CalcTangentSpace | // calculate tangents and bitangents if possible aiProcess_JoinIdenticalVertices | // join identical vertices/ optimize indexing aiProcess_ValidateDataStructure | // perform a full validation of the loader's output aiProcess_ImproveCacheLocality | // improve the cache locality of the output vertices aiProcess_RemoveRedundantMaterials | // remove redundant materials aiProcess_FindDegenerates | // remove degenerated polygons from the import aiProcess_FindInvalidData | // detect invalid model data, such as invalid normal vectors aiProcess_GenUVCoords | // convert spherical, cylindrical, box and planar mapping to proper UVs aiProcess_TransformUVCoords | // preprocess UV transformations (scaling, translation ...) aiProcess_FindInstances | // search for instanced meshes and remove them by references to one master aiProcess_LimitBoneWeights | // limit bone weights to 4 per vertex aiProcess_OptimizeMeshes | // join small meshes, if possible; aiProcess_SplitByBoneCount | // split meshes with too many bones. Necessary for our (limited) hardware skinning shader 0; cout << "Loading " << pFile << "... "; aiPropertyStore* props = aiCreatePropertyStore(); aiSetImportPropertyInteger(props,AI_CONFIG_IMPORT_TER_MAKE_UVS,1); aiSetImportPropertyFloat(props,AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE,80.f); aiSetImportPropertyInteger(props,AI_CONFIG_PP_SBP_REMOVE, aiPrimitiveType_LINE | aiPrimitiveType_POINT); aiSetImportPropertyInteger(props,AI_CONFIG_GLOB_MEASURE_TIME,1); //aiSetImportPropertyInteger(props,AI_CONFIG_PP_PTV_KEEP_HIERARCHY,1); // Call ASSIMPs C-API to load the file scene = (aiScene*)aiImportFileExWithProperties(pFile.c_str(), ppsteps | /* default pp steps */ aiProcess_GenSmoothNormals | // generate smooth normal vectors if not existing aiProcess_SplitLargeMeshes | // split large, unrenderable meshes into submeshes aiProcess_Triangulate | // triangulate polygons with more than 3 edges //aiProcess_ConvertToLeftHanded | // convert everything to D3D left handed space aiProcess_SortByPType | // make 'clean' meshes which consist of a single typ of primitives 0, NULL, props); aiReleasePropertyStore(props); if(!scene){ cout << aiGetErrorString() << endl; return 0; } this is the relevant piece of code in assimp view code // default pp steps unsigned int ppsteps = aiProcess_CalcTangentSpace | // calculate tangents and bitangents if possible aiProcess_JoinIdenticalVertices | // join identical vertices/ optimize indexing aiProcess_ValidateDataStructure | // perform a full validation of the loader's output aiProcess_ImproveCacheLocality | // improve the cache locality of the output vertices aiProcess_RemoveRedundantMaterials | // remove redundant materials aiProcess_FindDegenerates | // remove degenerated polygons from the import aiProcess_FindInvalidData | // detect invalid model data, such as invalid normal vectors aiProcess_GenUVCoords | // convert spherical, cylindrical, box and planar mapping to proper UVs aiProcess_TransformUVCoords | // preprocess UV transformations (scaling, translation ...) aiProcess_FindInstances | // search for instanced meshes and remove them by references to one master aiProcess_LimitBoneWeights | // limit bone weights to 4 per vertex aiProcess_OptimizeMeshes | // join small meshes, if possible; aiProcess_SplitByBoneCount | // split meshes with too many bones. Necessary for our (limited) hardware skinning shader 0; aiPropertyStore* props = aiCreatePropertyStore(); aiSetImportPropertyInteger(props,AI_CONFIG_IMPORT_TER_MAKE_UVS,1); aiSetImportPropertyFloat(props,AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE,g_smoothAngle); aiSetImportPropertyInteger(props,AI_CONFIG_PP_SBP_REMOVE,nopointslines ? aiPrimitiveType_LINE | aiPrimitiveType_POINT : 0 ); aiSetImportPropertyInteger(props,AI_CONFIG_GLOB_MEASURE_TIME,1); //aiSetImportPropertyInteger(props,AI_CONFIG_PP_PTV_KEEP_HIERARCHY,1); // Call ASSIMPs C-API to load the file g_pcAsset->pcScene = (aiScene*)aiImportFileExWithProperties(g_szFileName, ppsteps | /* configurable pp steps */ aiProcess_GenSmoothNormals | // generate smooth normal vectors if not existing aiProcess_SplitLargeMeshes | // split large, unrenderable meshes into submeshes aiProcess_Triangulate | // triangulate polygons with more than 3 edges aiProcess_ConvertToLeftHanded | // convert everything to D3D left handed space aiProcess_SortByPType | // make 'clean' meshes which consist of a single typ of primitives 0, NULL, props); aiReleasePropertyStore(props); As you can see the code is nearly identical because I copied from assimp view. What could be the reason for such a difference in performance? The two software are using the same dll Assimp64.dll (compiled in my computer with vc++ 2010 express) and the same function aiImportFileExWithProperties to load the model, so I assume that the actual code employed is the same. How is it possible that the function aiImportFileExWithProperties is 100 times slower when called by my sotware than when called by assimp view? What am I missing? I am not good with dll, dynamic and static libraries so I might be missing something obvious. ------------------------------ UPDATE I found out the reason why the code is going slower. Basically I was running my software with "Start debugging" in VC++ 2010 Express. If I run the code outside VC++ 2010 I get same performance of assimp view. However now I have a new question. Why does the dll perform slower in VC++ debugging? I compiled it in release mode without debugging information. Is there any way to have the dll go fast in debugmode i.e. not debugging the dll? Because I am interested in debugging only my own code, not the dll that I assume is already working fine. I do not want to wait 2 minutes every time I want to load my software to debug. Does this request make sense?

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  • Manager keeps changing requirement specification after every demo.

    - by Jungle Hunter
    Background of my working environment My manager has no background or understanding of computers or software whatsoever. It is highly likely he hasn't seen code in any form (not even from a physical distance of 10 feet or less) in his life. There is no one who understands the complexity of what I am asked to implement. To the point that if I semi-hardcode no one would know. On Joel's test we score an unbelievable score 0. The problems The manager and at times other "senior" keep changing the requirement specification. Changes which, if good engineering be done and not patchy "fixes", require change in the underlying design. There is absolutely no one who looks at code (probably because no one knows how to, or even if it should be done) which means no one will ever be able to: Appreciate the complexity of the problem or the elegance of the solution. Suggest improvement to the approach. Appreciate the quality of the code. Point out where the code can be improved. A lot of jargon is used which makes sense grammatically but fails to make any sense any other way. Doesn't feel, behave or work like a software company. The question What should be done? Especially regarding there being no one who would point out improvements in my code. Update To answer HLGEM's (and possibly others) question about what I've done to try and fix it. I offered to set up Redmine and introduce source control to everyone. I said I would recommend distributed (git or mercurial) but will also talk about centralized ones and let the team decide. Response was that things are being done and will be done within weeks. Haven't seen that nor am I aware if other parts of the company use it.

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  • Google Python Class Day 1 Part 3

    Google Python Class Day 1 Part 3 Google Python Class Day 1 Part 3: Dicts and Files. By Nick Parlante. Support materials and exercises: code.google.com From: GoogleDevelopers Views: 7 0 ratings Time: 28:59 More in Science & Technology

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  • Is there a way to use scala with html5?

    - by Maik Klein
    I want to create a very simple 2d multiplayer browsergame in html5. Something like Scalatron I mainly want to do this to improve my scala skills, the problem is I would have to code the clientside code in javascript and the serverside code in scala. This would result in duplicated code. Another option would be to ignore the html5 part and write it in opengl. But I would still prefer to have a html5 game. I could do this is in javascript, but then it would destroy the whole purpose of learning scala. Is there a way to use scala with html5? Or what would you recommend me to do?

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  • Does Open Source lead to bad coding?

    - by David Conde
    I have a thought that I tried asking at SO, but didnt seem like the appropriate place. I think that source sites like Google Code, GitHub, SourceForge... have played a major role in the history of programming. However, I found that there is another bad thing to these kind of sites and that is you may just "copy" code from almost anyone, not knowing if it is good(tested) source or not. This line of thought has taken me to believe that source code websites tend to lead many developers (most likely unexperienced) to copy/paste massive amounts of code, which I find just wrong. I really dont know how to focus the question well, but basic thought would be: Is this ok? Is Open Source contributing to that or I'm just seeing ghosts... Hope people get interested because I think this is an important theme.

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  • Oracle Partner Store: Neuer Registrierungsprozess für Partner-Deals

    - by A&C Redaktion
    Vor kurzem wurden Sie per Email über die Neuerungen bei der Registrierung von Partner-Deals und -Opportunities informiert. Der Oracle Partner Store (OPS) soll nicht nur den Prozess vereinfachen und transparenter machen, sondern ein allumfassendes Tool für Sie werden: Von der Registrierung eines Deals (mit gleichzeitigem Projektschutz) über die tägliche Status-Anzeige bis zur abschließenden Bestellung können Sie ab 17. November 2012 alles im OPS verwalten. Nutzen Sie einfach eines der deutschen OPS-Trainings von Oracle University:  7. November 2012  10:00 CET Tel.: 069/22 22 16 106Conference Code: 4244390#Security Code: 008800# Webkonferenz-LinkPasswort: Partner1  14. November 2012  11:00 CET Tel.: 069/22 22 16 106Conference Code: 4244390#Security Code: 008800# Webkonferenz-LinkPasswort: Partner1  20. November 2012 10:00 CET Aufgezeichnetes Training von Oracle University Request ID: 10952(Link wird nachgereicht) Weitere Termine und Sprachen finden Sie hier.

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  • Oracle Partner Store: Neuer Registrierungsprozess für Partner-Deals

    - by A&C Redaktion
    Vor kurzem wurden Sie per Email über die Neuerungen bei der Registrierung von Partner-Deals und -Opportunities informiert. Der Oracle Partner Store (OPS) soll nicht nur den Prozess vereinfachen und transparenter machen, sondern ein allumfassendes Tool für Sie werden: Von der Registrierung eines Deals (mit gleichzeitigem Projektschutz) über die tägliche Status-Anzeige bis zur abschließenden Bestellung können Sie ab 17. November 2012 alles im OPS verwalten. Nutzen Sie einfach eines der deutschen OPS-Trainings von Oracle University:  7. November 2012  10:00 CET Tel.: 069/22 22 16 106Conference Code: 4244390#Security Code: 008800# Webkonferenz-LinkPasswort: Partner1  14. November 2012  11:00 CET Tel.: 069/22 22 16 106Conference Code: 4244390#Security Code: 008800# Webkonferenz-LinkPasswort: Partner1  20. November 2012 10:00 CET Aufgezeichnetes Training von Oracle University Request ID: 10952(Link wird nachgereicht) Weitere Termine und Sprachen finden Sie hier.

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  • How to enable services Discovery API in GoogleCL?

    - by Marcos
    There are bits and pieces of information all over the place but I'm trying to put it all together so that GoogleCL finally accesses more than the initial 7 services. Does anyone know of a step-by-step? Right now any attempt outside these result in the error message: google tasks list Did you specify the service correctly? Must be one of 'picasa', 'blogger', 'youtube', 'docs', 'contacts', 'calendar', 'finance' I installed GoogleCL from the Ubuntu repos, authenticated a few bundled services like contacts, docs etc. and those work great, giving me access to do certain operations like upload from the command line. I would really like to get it going to support tasks and all the other elegible Google services shown at https://code.google.com/apis/explorer/#_s=tasks Here are some guides/partial steps I've found: http://code.google.com/p/googlecl/wiki/DiscoveryManual (indicates needing to check it out updated GoogleCL from the subversion repository.) http://code.google.com/p/google-api-python-client/wiki/Installation easy_install --upgrade google-api-python-client http://code.google.com/p/googlecl/wiki/Install http://code.google.com/p/googlecl/source/checkout sudo -i cd /usr/local/src/ svn checkout http://googlecl.googlecode.com/svn/trunk/ googlecl-read-only cat googlecl-read-only/INSTALL.txt cd /usr/local/src/googlecl-read-only/ python setup.py install Result: $ google discovery list Traceback (most recent call last): File "/usr/bin/google", line 488, in run_interactive run_once(options, args) File "/usr/bin/google", line 540, in run_once options.config) File "/usr/bin/google", line 364, in import_service force_gdata_v1 = config.lazy_get(package.SECTION_HEADER, AttributeError: 'module' object has no attribute 'SECTION_HEADER'

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  • Using ASP.NET C# and Javascript

    - by ctck
    I'm looking for the most efficient / standardized way of passing data between client javascript code and C# code behind in an ASP.NET application. Currently ive been using the following methods to achieve this but they all feel a bit like a fudge. The way i pass data from javascript to the C# code behind is by setting hidden asp variables and triggering a postback <asp:HiddenField ID="RandomList" runat="server" /> function SetDataField(data) { document.getElementById('<%=RandomList.ClientID%>').value = data; } Then in C# code i collect the list protected void GetData(object sender, EventArgs e) { var _list = RandomList.value; } Going back the other way i often use either scriptmanager to register a function and pass it data during Page_Load: ScriptManager.RegisterStartupScript(this.GetType(), "Set","get("Test();",true); or i add attributes to controls before a post back or during Initialization / pre rendering stages: Btn.Attributes.Add("onclick", "DisplayMessage("Hello");"); These methods have served me well and do the job. However they just dont feel complete. Is there a more standardized way of passing data between client side markup / javascript and backend code. Ive seen some posts like this one: Injecting JavaScrip : StackOverflow that describe HtmlElement class. Is this something is should look into? Thanks everyone for your time.

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  • Google Chrome Extensions Developer Snapshots - Aviary

    Google Chrome Extensions Developer Snapshots - Aviary Avi Muchnik, CEO and Co-founder of Aviary (www.aviary.com) discusses his company's experience with the Google Chrome extensions platform. To learn more on creating Google Chrome Extensions please visit code.google.com/chrome/extensions or chek out the gallery at chrome.google.com/extensions. From: GoogleDevelopers Views: 7 0 ratings Time: 04:33 More in Science & Technology

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  • .NET Reflector Pro to the rescue

    Almost all applications have to interface with components or modules written by somebody else, for which you don't have the source code. This is fine until things go wrong, but when you need to refactor your code and you keep getting strange exceptions, you'll start to wish you could place breakpoints in someone else's code and step through it. Now, of course, you can, as Geoffrey Braaf discovered.

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  • Notes for a NetBeans IDE 7.4 HTML5 Screencast

    - by Geertjan
    I'm making a screencast that intends to thoroughly introduce NetBeans IDE 7.4 as a tool for HTML, JavaScript, and CSS developers. Here's the current outline, additions and other suggestions are welcome. Getting Started Downloading NetBeans IDE for HTML5 and PHP Examining the NetBeans installation directory, especially netbeans.conf Examining the NetBeans user directory Command line options for starting NetBeans IDE Exploring NetBeans IDE Menus and toolbars Versioning tools Options Window Go through whole Options window Change look and feels Adding themes Syntax coloring Code templates Plugin Manager and Plugin Portal Dark Look and Feel Themes Toggle line wrap Emmet HTML Tidy NetBeans Cheat Sheets Creating HTML5 projects From scratch From online template, e.g., Twitter Bootstrap From ZIP file From folder on disk From sample Editing Useful shortcuts Alt-Enter: see the current hints Alt-Shift-DOT/COMMA: expand selection (CTRL instead of Alt on Mac) Ctrl-Shift-Up/Down: copy up/down Alt-Shift-Up/Down: move up/down Alt-Insert: generate code (Lorum Ipsum) View menu | Show Non-printable Characters Source menu Show keyboard shortcut card Useful hints Surround with Tag Remove Surrounding Tag Useful code completion Link tag for CSS, show completion Script tag for JavaScript, show completion Create code templates in Options window Useful HTML Palette items Unordered List Link Useful code navigation Navigator Navigate menu Useful project settings Project-level deployment settings CSS Preprocessors (SASS/LESS) Cordova support Useful window management Dragging, minimizing, undocking Ctrl-Shift-Enter: distraction-free mode Alt-Shift Enter: maximization Debugging JavaScript debugger Deploying Embedded browser Responsive design Inspect in NetBeans mode Chrome browser with NetBeans plugin Android and iOS browsers Cordova makes native packages On device debugging On device styling Documentation PHP and HTML5 Learning Trail: https://netbeans.org/kb/trails/php.html Contributing Social Media: Twitter, Facebook, blogs Plugin Portal Planning to complete the above screencast this week, will continue editing this page as more useful features arise in my mind or hopefully in the comments in this blog entry!

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  • Google Chrome Extensions Developer Snapshots - Glue

    Google Chrome Extensions Developer Snapshots - Glue Karen Teng, VP Engineering of Adaptive Blue (www.getglue.com), discusses her company's experience with the Google Chrome extensions platform. To learn more on creating Google Chrome Extensions please visit code.google.com/chrome/extensions or chek out the gallery at chrome.google.com/extensions. From: GoogleDevelopers Views: 4 0 ratings Time: 05:34 More in Science & Technology

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  • URL Routing in ASP.NET 4.0

    In the .NET Framework 3.5 SP1, Microsoft introduced ASP.NET Routing, which decouples the URL of a resource from the physical file on the web server. With ASP.NET Routing you, the developer, define routing rules map route patterns to a class that generates the content. For example, you might indicate that the URL <code>Categories/<i>CategoryName</i></code> maps to a class that takes the <i>CategoryName</i> and generates HTML that lists that category's products in a grid. With such a mapping, users could view products for the Beverages category by visiting <code>www.yoursite.com/Categories/Beverages</code>.In .NET 3.5 SP1, ASP.NET Routing was primarily designed for <a href="http://www.asp.net/mvc/">ASP.NET MVC</a>

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  • Linking Libraries in iOS?

    - by Joey Green
    This is probably a totally noob question but I have missing links in my mind when thinking about linking libraries in iOS. I usually just add a new library that's been cross compiled and set the build and linker paths without really know what I'm doing. I'm hoping someone can help me fill in some gaps. Let's take the OpenCV library for instance. I have this totally working btw because of a really well written tutorial( http://niw.at/articles/2009/03/14/using-opencv-on-iphone/en ), but I'm just wanting to know what is exactly going on. What I'm thinking is happening is that when I build OpenCV for iOS is that your creating object code that gets placed in the .a files. This object code is just the implementation files( .m ) compiled. One reason you would want to do this is to make it hard to see the source code and so that you don't have to compile that source code every time. The .h files won't be put in the library ( .a ). You include the .h in your source files and these header files communicate with the object code library ( .a ) in some way. You also have to include the header files for your library in the Build Path and the Library itself in the Linker Path. So, is the way I view linking libraries correct? If , not can someone correct me on this ?

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  • Google I/O 2010 - Google Buzz, location, and social gaming

    Google I/O 2010 - Google Buzz, location, and social gaming Google I/O 2010 - Surf the stream: Google Buzz, location, and social gaming Social Web 201 Bob Aman, Timothy Jordan Google Buzz has a feature-rich API that allows you to do all kinds of interesting things with conversations and location. In this session we'll build a Buzz-tastic mobile game using App Engine, HTML5, and the Buzz API for social awesomeness. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 2 0 ratings Time: 31:18 More in Science & Technology

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  • How can I convince cowboy programmers to use source control?

    - by P.Brian.Mackey
    UPDATE I work on a small team of devs, 4 guys. They have all used source control. Most of them can't stand source control and instead choose not to use it. I strongly believe source control is a necessary part of professional development. Several issues make it very difficult to convince them to use source control: The team is not used to using TFS. I've had 2 training sessions, but was only allotted 1 hour which is insufficient. Team members directly modify code on the server. This keeps code out of sync. Requiring comparison just to be sure you are working with the latest code. And complex merge problems arise Time estimates offered by developers exclude time required to fix any of these problems. So, if I say nono it will take 10x longer...I have to constantly explain these issues and risk myself because now management may perceive me as "slow". The physical files on the server differ in unknown ways over ~100 files. Merging requires knowledge of the project at hand and, therefore, developer cooperation which I am not able to obtain. Other projects are falling out of sync. Developers continue to have a distrust of source control and therefore compound the issue by not using source control. Developers argue that using source control is wasteful because merging is error prone and difficult. This is a difficult point to argue, because when source control is being so badly mis-used and source control continually bypassed, it is error prone indeed. Therefore, the evidence "speaks for itself" in their view. Developers argue that directly modifying server code, bypassing TFS saves time. This is also difficult to argue. Because the merge required to synchronize the code to start with is time consuming. Multiply this by the 10+ projects we manage. Permanent files are often stored in the same directory as the web project. So publishing (full publish) erases these files that are not in source control. This also drives distrust for source control. Because "publishing breaks the project". Fixing this (moving stored files out of the solution subfolders) takes a great deal of time and debugging as these locations are not set in web.config and often exist across multiple code points. So, the culture persists itself. Bad practice begets more bad practice. Bad solutions drive new hacks to "fix" much deeper, much more time consuming problems. Servers, hard drive space are extremely difficult to come by. Yet, user expectations are rising. What can be done in this situation?

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  • Google I/O 2010: Google TV Keynote - Developer And Partner Timeline

    Google I/O 2010: Google TV Keynote - Developer And Partner Timeline Due to licensing and permissions issues, we are unable to show the full Google TV demonstration from the Day 2 keynote at Google I/O. Until we are able to get these permissions, please check out these clips. For Google I/O session videos, presentations, developer interviews and more, go to: code.google.com/io From: GoogleDevelopers Views: 1 0 ratings Time: 04:47 More in Science & Technology

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  • Google Developer Day 2010 - Highlights

    Google Developer Day 2010 - Highlights Highlights from Google Developer Day 2010 in Tokyo, Sao Paulo, Munich, Moscow and Prague. www.google.com All photos & videos at www.google.com Follow us on the Code blog and Twitter to stay updated on developer news: googlecode.blogspot.com http Hashtags: #gdd2010jp #gddbr #gddde #gddru #gddcz From: GoogleDevelopers Views: 2524 48 ratings Time: 02:53 More in Science & Technology

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  • Geometry Shader: distortions

    - by Christophe Lionet
    This is a cross-question from Stack Overflow, I thought it would be more appropriate here. There is a lot of code I could be posting. To avoid overloading the page with code, I will post any part of the code if requested. I am working from the ParticleGS DirectX10 sample, to build a geometry shader based particle system in DirectX 11. Using the sample code, and changing it to my liking, I am able to draw a single quad (which is essentially one particle constantly recreating itself). However, I noticed a problem which was similar to one I once had: the rendered shape is distorted. Here is a video showcasing what is happening. http://youtu.be/6NY_hxjMfwY Now, I used to have this issue when using several effects together, when I realised that I needed to explicitely set the geometry shader to null for the other effects. I solved this problem, as you can see in the video, as the rest of the scene is drawing properly. Note that some sides are being culled somehow, although I turned off culling in my main render state. The texturing is fine too, the texture draws with appropriate proportions relative to the quad. I really don't see what I could be doing wrong here... what would cause the geometry shader to behave in such a way? Again, I will post any piece code you will request.

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  • .NET 4: &ldquo;Slim&rdquo;-style performance boost!

    - by Vitus
    RTM version of .NET 4 and Visual Studio 2010 is available, and now we can do some test with it. Parallel Extensions is one of the most valuable part of .NET 4.0. It’s a set of good tools for easily consuming multicore hardware power. And it also contains some “upgraded” sync primitives – Slim-version. For example, it include updated variant of widely known ManualResetEvent. For people, who don’t know about it: you can sync concurrency execution of some pieces of code with this sync primitive. Instance of ManualResetEvent can be in 2 states: signaled and non-signaled. Transition between it possible by Set() and Reset() methods call. Some shortly explanation: Thread 1 Thread 2 Time mre.Reset(); mre.WaitOne(); //code execution 0 //wating //code execution 1 //wating //code execution 2 //wating //code execution 3 //wating mre.Set(); 4 //code execution //… 5 Upgraded version of this primitive is ManualResetEventSlim. The idea in decreasing performance cost in case, when only 1 thread use it. Main concept in the “hybrid sync schema”, which can be done as following:   internal sealed class SimpleHybridLock : IDisposable { private Int32 m_waiters = 0; private AutoResetEvent m_waiterLock = new AutoResetEvent(false);   public void Enter() { if (Interlocked.Increment(ref m_waiters) == 1) return; m_waiterLock.WaitOne(); }   public void Leave() { if (Interlocked.Decrement(ref m_waiters) == 0) return; m_waiterLock.Set(); }   public void Dispose() { m_waiterLock.Dispose(); } } It’s a sample from Jeffry Richter’s book “CLR via C#”, 3rd edition. Primitive SimpleHybridLock have two public methods: Enter() and Leave(). You can put your concurrency-critical code between calls of these methods, and it would executed in only one thread at the moment. Code is really simple: first thread, called Enter(), increase counter. Second thread also increase counter, and suspend while m_waiterLock is not signaled. So, if we don’t have concurrent access to our lock, “heavy” methods WaitOne() and Set() will not called. It’s can give some performance bonus. ManualResetEvent use the similar idea. Of course, it have more “smart” technics inside, like a checking of recursive calls, and so on. I want to know a real difference between classic ManualResetEvent realization, and new –Slim. I wrote a simple “benchmark”: class Program { static void Main(string[] args) { ManualResetEventSlim mres = new ManualResetEventSlim(false); ManualResetEventSlim mres2 = new ManualResetEventSlim(false);   ManualResetEvent mre = new ManualResetEvent(false);   long total = 0; int COUNT = 50;   for (int i = 0; i < COUNT; i++) { mres2.Reset(); Stopwatch sw = Stopwatch.StartNew();   ThreadPool.QueueUserWorkItem((obj) => { //Method(mres, true); Method2(mre, true); mres2.Set(); }); //Method(mres, false); Method2(mre, false);   mres2.Wait(); sw.Stop();   Console.WriteLine("Pass {0}: {1} ms", i, sw.ElapsedMilliseconds); total += sw.ElapsedMilliseconds; }   Console.WriteLine(); Console.WriteLine("==============================="); Console.WriteLine("Done in average=" + total / (double)COUNT); Console.ReadLine(); }   private static void Method(ManualResetEventSlim mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } }   private static void Method2(ManualResetEvent mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } } } I use 2 concurrent thread (the main thread and one from thread pool) for setting and resetting ManualResetEvents, and try to run test COUNT times, and calculate average execution time. Here is the results (I get it on my dual core notebook with T7250 CPU and Windows 7 x64): ManualResetEvent ManualResetEventSlim Difference is obvious and serious – in 10 times! So, I think preferable way is using ManualResetEventSlim, because not always on calling Set() and Reset() will be called “heavy” methods for working with Windows kernel-mode objects. It’s a small and nice improvement! ;)

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  • Google Python Class Day 2 Part 2

    Google Python Class Day 2 Part 2 Google Python Class Day 2 Part 2: Utilities: OS and Commands. By Nick Parlante. Support materials and exercises: code.google.com From: GoogleDevelopers Views: 11 1 ratings Time: 20:20 More in Science & Technology

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