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  • Efficient mapping layout in 2D side-scroller, and collisions between character and the world

    - by Jack
    I haven't touched Visual Studio for a couple months now, but I was playing a game from the '90s toady and had an epiphany: I was looking for something what i didn't need, and I wasn't using what I knew correctly. One of those realizations was collision, so let me tell you a bit about my project that I was working on. The project's graphics looks like Mario or Dangerous Dave, etc., you get the idea - old-school pixels. So anyway I remember trying to think of something else than AABB for character form, but I couldn't think of anything. Perhaps I could get a suggestion for this? Another thing is the world - I don't want it to be just linear world, I want mountains, etc.. My idea is to use triangles, and no idea yet what to do if I want just part of the cube, say 3/4 or 2/4 or whatever. Hard-coding such things seems inefficient. P.S. I am not looking at the precision level offered by Box2D. Actually I remember trying to implement it at first, but I failed as my understanding of C++ wasn't advanced enough, as it'll be mentioned below. P.P.S. I am programming in C++, and I haven't done it for a couple months now. I have no means of testing it either, as my PC is broken down, and this one can barely run games from late '90s, not to speak about a compiler or a program with inefficient resource management... I am also not an expert (obviously), I don't even know if I can consider myself an average programmer. In short, I am simply curious about my thoughts and my past experience when programming the game. I may come back to it when my PC is fixed, I'm already filling a note about these things.

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  • What's a good Game development platform for a platformer game with these characteristics?

    - by Joe
    Yes, I know, the best way to make an indie game is to learn to code. I've got some scripting experience, but I want to do worldbuilding with already-existing tools (and communities surrounding those tools), and I've been really impressed with games like An Untitled Story that were made with pre-packaged toolsets at their core, like Game Maker. :) So I'm planning to make my game using either Game Maker or something like it. The basic parameters of my planned game: -2D platformer. -Physics/speed akin to Sonic the Hedgehog. -Large, non-linear world, flowing as seamlessly as possible -- think Super Metroid, but without the forced screen transitions. The first two points have me leaning toward Game Maker -- Plenty of 2D platformers have been made with it, and there are serviceable, openly available Sonic-the-Hedgehog-style physics engines for it that could be adapted to my needs with minimal muss and fuss. But the third makes me antsy -- from what limited information I hear, Game Maker has problems with large levels/boards/screens/whateveryoucallthem, thus necessitating transitions between screens. I want to avoid that if at all possible -- it would, I believe, fundamentally alter the flow of the game. I understand that generally speaking, the more you have loaded into memory the more things are going to chug (especially for a one-size-fits-all game development platform that isn't a model of efficient coding), but I'm hoping there are systems that can un-load objects that are sufficiently far offscreen and thus better produce seamlessness. Any thoughts, people? :) The sooner I can get a basic pre-fab physics engine and world-building program up and running, the sooner I can start prototyping areas and generally tooling around. Should I be looking at Game Maker, or elsewhere? (My current plan is to more-or-less build the game prototype-style, then worry about art and sound at the very end once the damn thing is playable.)

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  • How do I draw a point sprite using OpenGL ES on Android?

    - by nbolton
    Edit: I'm using the GL enum, which is incorrect since it's not part of OpenGL ES (see my answer). I should have used GL10, GL11 or GL20 instead. Here's a few snippets of what I have so far... void create() { renderer = new ImmediateModeRenderer(); tiles = Gdx.graphics.newTexture( Gdx.files.getFileHandle("res/tiles2.png", FileType.Internal), TextureFilter.MipMap, TextureFilter.Linear, TextureWrap.ClampToEdge, TextureWrap.ClampToEdge); } void render() { Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); Gdx.gl.glClearColor(0.6f, 0.7f, 0.9f, 1); } void renderSprite() { int handle = tiles.getTextureObjectHandle(); Gdx.gl.glBindTexture(GL.GL_TEXTURE_2D, handle); Gdx.gl.glEnable(GL.GL_POINT_SPRITE); Gdx.gl11.glTexEnvi(GL.GL_POINT_SPRITE, GL.GL_COORD_REPLACE, GL.GL_TRUE); renderer.begin(GL.GL_POINTS); renderer.vertex(pos.x, pos.y, pos.z); renderer.end(); } create() is called once when the program starts, and renderSprites() is called for each sprite (so, pos is unique to each sprite) where the sprites are arranged in a sort-of 3D cube. Unfortunately though, this just renders a few white dots... I suppose that the texture isn't being bound which is why I'm getting white dots. Also, when I draw my sprites on anything other than 0 z-axis, they do not appear -- I read that I need to crease my zfar and znear, but I have no idea how to do this using libgdx (perhaps it's because I'm using ortho projection? What do I use instead?). I know that the texture is usable, since I was able to render it using a SpriteBatch, but I guess I'm not using it properly with OpenGL.

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  • Vector with Constant-Time Remove - still a Vector?

    - by Darrel Hoffman
    One of the drawbacks of most common implementations of the Vector class (or ArrayList, etc. Basically any array-backed expandable list class) is that their remove() operation generally operates in linear time - if you remove an element, you must shift all elements after it one space back to keep the data contiguous. But what if you're using a Vector just to be a list-of-things, where the order of the things is irrelevant? In this case removal can be accomplished in a few simple steps: Swap element to be removed with the last element in the array Reduce size field by 1. (No need to re-allocate the array, as the deleted item is now beyond the size field and thus not "in" the list any more. The next add() will just overwrite it.) (optional) Delete last element to free up its memory. (Not needed in garbage-collected languages.) This is clearly now a constant-time operation, since only performs a single swap regardless of size. The downside is of course that it changes the order of the data, but if you don't care about the order, that's not a problem. Could this still be called a Vector? Or is it something different? It has some things in common with "Set" classes in that the order is irrelevant, but unlike a Set it can store duplicate values. (Also most Set classes I know of are backed by a tree or hash map rather than an array.) It also bears some similarity to Heap classes, although without the log(N) percolate steps since we don't care about the order.

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  • Duplication of code (backend and javascript - knockout)

    - by Michal B.
    We have a new developer in our team. He seems a smart guy (he just came in so I cannot really judge). He started with implementing some small enhancements in the project (MVC3 web application using javascript - jquery and knockout). Let's say we have two values: A - quite complex calculation C - constant B = A + C On the screen there is value B and user can change it (normal texbox). When B changes, A changes as well because C is constant. So there is linear dependency between A and B. Now, all the calculations are done in the backend, but we need to recalculate A as user changes B (in js, I would use knockout). I thought about storing old A and B and when B changes by 10 then we know that new A will be old A + 10. He says this is dirty, because it's duplication of code (we make use of the fact that they are dependent and according to him that should be only in one place in our app). I understand it's not ideal, but making AJAX request after every key press seems a bit too much. It's a really small thing and I would not post if we haven't had long discussion about it. How do you deal with such problems? Also I can imagine that using knockout implies lots of calculations on the client side, which very often leads to duplication of the same calculations from the backend. Does anyone have links to some articles/thoughts on this topic?

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  • CodePlex Daily Summary for Friday, August 31, 2012

    CodePlex Daily Summary for Friday, August 31, 2012Popular ReleasesStartComp: Beta Release 1.0.0: Beta Release 1 Featured Content Bing-Search has been removed Window anchor implemented The listview can now be configured to be shown in details view or tile view through the context menu The listview now allows sorting through the context menu The view, sort order and sort column are now saved for each repository The listview now shows the background image in the lower right The listview now shows a background image for the user defined repositories Added a "Tell-A-Friend" bu...SharePoint Column & View Permission: SharePoint Column and View Permission v1.2: Version 1.2 of this project. If you will find any bugs please let me know at enti@zoznam.sk or post your findings in Issue TrackerDotNetNuke® Form and List: 06.00.04: DotNetNuke Form and List 06.00.04 Don't forget to backup your installation before upgrade. Changes in 06.00.04 Fix: Sql Scripts for 6.003 missed object qualifiers within stored procedures Fix: added missing resource "cmdCancel.Text" in form.ascx.resx Changes in 06.00.03 Fix: MakeThumbnail was broken if the application pool was configured to .Net 4 Change: Data is now stored in nvarchar(max) instead of ntext Changes in 06.00.02 The scripts are now compatible with SQL Azure, tested in a ne...DotNetNuke Translator: 01.00.00 Beta: First release of the project.Audio Pitch & Shift: Audio Pitch And Shift 5.1.0.2: fixed several issues with streaming modeUrlPager: UrlPager 1.2: Fixed bug in which url parameters will lost after paging; ????????url???bug;EntLib.com????????: EntLib.com???????? v3.0: EntLib eCommerce Solution ???Microsoft .Net Framework?????????????????????。Coevery - Free CRM: Coevery 1.0.0.24: Add a sample database, and installation instructions.NicAudio: NicAudio 2.0.6: ac3,dts Solved some initialization issues with no-linear decode.ExpressProfiler: Initial release of ExpressProfiler v1.2: This is initial release of ExpressProfilerNabu Library: 2012-08-29, 14: .Net Framework 4.0, .Net Framework 4.5 Debug and Release builds.Math.NET Numerics: Math.NET Numerics v2.2.1: Major linear algebra rework since v2.1, now available on Codeplex as well (previous versions were only available via NuGet). Since v2.2.0: Student-T density more robust for very large degrees of freedom Sparse Kronecker product much more efficient (now leverages sparsity) Direct access to raw matrix storage implementations for advanced extensibility Now also separate package for signed core library with a strong name (we dropped strong names in v2.2.0) Also available as NuGet packages...Microsoft SQL Server Product Samples: Database: AdventureWorks Databases – 2012, 2008R2 and 2008: About this release This release consolidates AdventureWorks databases for SQL Server 2012, 2008R2 and 2008 versions to one page. Each zip file contains an mdf database file and ldf log file. This should make it easier to find and download AdventureWorks databases since all OLTP versions are on one page. There are no database schema changes. For each release of the product, there is a light-weight and full version of the AdventureWorks sample database. The light-weight version is denoted by ...DotNetNuke® Blog: 05.00.00: Version 5.0.0 - Final This version of the module requires DotNetNuke Core 6.2 or greater. FYI: Developers should be aware that the module uses Visual Studio 2010 only. Release Highlights: Corrected blog comment sorting problem. 20228 - Integrated with the core Journal API. 20789, 21988 - wired in fix submitted by J Sheely around blank author names. 20210 - Updated manifest to 5.0 format (from 3.0). Automated packaging and made project structure more inline with other DotNetNuke m...Christoc's DotNetNuke Module Development Template: DotNetNuke Project Templates V1.1 for VS2012: This release is specifically for Visual Studio 2012 Support, distributed through the Visual Studio Extensions gallery at http://visualstudiogallery.msdn.microsoft.com/ After you build in Release mode the installable packages (source/install) can be found in the INSTALL folder now, within your module's folder, not the packages folder anymore Check out the blog post for all of the details about this release. http://www.dotnetnuke.com/Resources/Blogs/EntryId/3471/New-Visual-Studio-2012-Projec...Home Access Plus+: v8.0: v8.0828.1800 RELEASE CHANGED TO BETA Any issues, please log them on http://www.edugeek.net/forums/home-access-plus/ This is full release, NO upgrade ZIP will be provided as most files require replacing. To upgrade from a previous version, delete everything but your AppData folder, extract all but the AppData folder and run your HAP+ install Documentation is supplied in the Web Zip The Quota Services require executing a script to register the service, this can be found in there install di...Phalanger - The PHP Language Compiler for the .NET Framework: 3.0.0.3406 (September 2012): New features: Extended ReflectionClass libxml error handling, constants DateTime::modify(), DateTime::getOffset() TreatWarningsAsErrors MSBuild option OnlyPrecompiledCode configuration option; allows to use only compiled code Fixes: ArgsAware exception fix accessing .NET properties bug fix ASP.NET session handler fix for OutOfProc mode DateTime methods (WordPress posting fix) Phalanger Tools for Visual Studio: Visual Studio 2010 & 2012 New debugger engine, PHP-like debugging ...MabiCommerce: MabiCommerce 1.0.1: What's NewSetup now creates shortcuts Fix spelling errors Minor enhancement to the Map window.ScintillaNET: ScintillaNET 2.5.2: This release has been built from the 2.5 branch. Version 2.5.2 is functionally identical to the 2.5.1 release but also includes the XML documentation comments file generated by Visual Studio. It is not 100% comprehensive but it will give you Visual Studio IntelliSense for a large part of the API. Just make sure the ScintillaNET.xml file is in the same folder as the ScintillaNET.dll reference you're using in your projects. (The XML file does not need to be distributed with your application)....BlackJumboDog: Ver5.7.1: 2012.08.25 Ver5.7.1 (1)?????·?????LING?????????????? (2)SMTP???(????)????、?????\?????????????????????New ProjectsAbcLibrary: A Library of methods and class types used for ABCAprendendo Windows 8: Não foi feito nada ainda...Auto fill template generator (word): This program was designed to help the automate generation of files using keywords.ClarkTestCodePlex2: clark test Code Razor: This tools translates Razor files to code. This allows the Razor views to be compiled and shared across projects.Contrib.Mod.ChangePassword: It is an evil module that abuses users rights and lets you change anyone's password.CurrentConsumption: CurrentConsumptionDbSettings - An API to store settings in a database: This stores settings in an OleDb/Sql database using an API similar to ApplicationSettingsBase. Settings vary by app, version, user.JCI prototipos: summaryMemberAdminService: This is a test projectMeteor Rendering Engine: The Meteor rendering engine is developed in C# with XNA 4.0, and provides various rendering outputs for 3D scenes.Mod.Colorbox: Orchard module for Mod.ColorboxMogulTestProject1: papaMogulTestTRY: papaosmm: this is a sample test projectServer Survey: Server Survey ScriptShops' Cloud: This project is a Cloud Platform for Mini Shops' Daily Management.Simple Grocery 5: This is a very simple application to help me (or you) out setting up a grocery list and use it on the food market using ALL smart phones or tablets.Tikun Korim: Community site to help people learn to read in Sefer Torah. This project is going to use ASP.NET MVC 4 and as much as open source project as we can. TreeCreeper: TreeCreeper programs (Spatial and NonSpatial) support the taxonomic analysis of species assemblagesVisual Studio Icon Patcher: Visual Studio Icon Patcher allows you to update Visual Studio 2012 with the Solution Explorer icons from Visual Studio 2010.WPT Generator: WPT Generator HTML5 , Google API 3.0, Javascript and CSS 3.0 Web Application for generating a WPT file (Ozi Explorer Format).

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  • How to go from Mainframe to the Cloud?

    - by Ruma Sanyal
    Running applications on IBM mainframes is expensive, complex, and hinders IT responsiveness. The high costs from frequent forced upgrades, long integration cycles, and complex operations infrastructures can only be alleviated by migrating away from a mainframe environment.  Further, data centers are planning for cloud enablement pinned on principles of operating at significantly lower cost, very low upfront investment, operating on commodity hardware and open, standards based systems, and decoupling of hardware, infrastructure software, and business applications. These operating principles are in direct contrast with the principles of operating businesses on mainframes. By utilizing technologies such as Oracle Tuxedo, Oracle Coherence, and Oracle GoldenGate, businesses are able to quickly and safely migrate away from their IBM mainframe environments. Further, running Oracle Tuxedo and Oracle Coherence on Oracle Exalogic, the first and only integrated cloud machine on the market, Oracle customers can not only run their applications on standards-based open systems, significantly cutting their time to market and costs, they can start their journey of cloud enabling their mainframe applications. Oracle Tuxedo re-hosting tools and techniques can provide automated migration coverage for more than 95% of mainframe application assets, at a fraction of the cost Oracle GoldenGate can migrate data from mainframe systems to open systems, eliminating risks associated with the data migration Oracle Coherence hosts transactional data in memory providing mainframe-like data performance and linear scalability Running Oracle software on top of Oracle Exalogic empowers customers to start their journey of cloud enabling their mainframe applications Join us in a series of events across the globe where you you'll learn how you can build your enterprise cloud and add tremendous value to your business. In addition, meet with Oracle experts and your peers to discuss best practices and see how successful organizations are lowering total cost of ownership and achieving rapid returns by moving to the cloud. Register for the Oracle Fusion Middleware Forum event in a city new you!

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  • Acer Aspire One 725 - missing graphic card driver for Radeon HD 7290?

    - by Melon
    Recently I bought an Acer Aspire One 725 Netbook and installed Ubuntu 12.10 on it. I bought it, because it can run HD movies and has Full HD on external VGA port. However, movies from youtube have a really slow framerate. If you open three tabs in Opera (for example g-mail, youtube and askubuntu) it gets really laggy. My suspicion is that the driver for graphic card is missing. When I check the System->Details->Graphics the driver is unknown. After running lspci | grep VGA I get this output: 00:01.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Device 980a From what I see, I have a AMD C70 processor integrated with AMD Radeon HD 7290. Has anyone had the same problem? Do you know which drivers need to be installed for the graphics to work properly? On official Acer page there are only drivers for Win7 and Win8... Update: OK. Another attempt. I have a fresh Ubuntu 12.10. All updates done. downloaded Catalyst 12.11 beta drivers and decided to create a package. After installing package, I have this error from /var/log/Xorg.0.log: [ 13.394] (**) fglrx(0): NoAccel = NO [ 13.394] (**) fglrx(0): AMD 2D Acceleration Architecture enabled [ 13.394] (--) fglrx(0): Chipset: "AMD Radeon HD 7290 Graphics" (Chipset = 0x980a) [ 13.394] (--) fglrx(0): (PciSubVendor = 0x1025, PciSubDevice = 0x0740) [ 13.394] (==) fglrx(0): board vendor info: third party graphics adapter - NOT original AMD [ 13.394] (--) fglrx(0): Linear framebuffer (phys) at 0xe0000000 [ 13.394] (--) fglrx(0): MMIO registers at 0xf0200000 [ 13.394] (--) fglrx(0): I/O port at 0x00003000 [ 13.394] (==) fglrx(0): ROM-BIOS at 0x000c0000 [ 13.484] (II) fglrx(0): ATIF platform detected [ 13.564] (II) fglrx(0): AC Adapter is used [ 13.565] (EE) fglrx(0): V_BIOS address 0xd00 out of range [ 13.565] (EE) fglrx(0): Failed to obtain VBIOS from Kernel! [ 13.565] (EE) fglrx(0): VBIOS read from Kernel, Invalid signature! [ 13.565] (EE) fglrx(0): GetBIOSParameter failed [ 13.565] (EE) fglrx(0): PreInitAdapter failed [ 13.565] (EE) fglrx(0): PreInit failed [ 13.565] (II) fglrx(0): === [xdl_xs113_atiddxPreInit] === end

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  • What's the proper way to merge two projects in source control software

    - by Mallow
    I'm using Fossil-SCM to maintain my projects. Since I don't work in a team I usually have just a very linear branch of development: 1.0 - 1.1 - 1.2 I'm wondering what the procedure is when you have one project who's task is about to be given to a related project. And thereby rendering the first project obsolete. Although I tend to rewrite most of my code if I don't remember having already written it, I still would like to keep the code archived. And I'ld rather not have a fossil repo that just is dead. Can I merge it? Is that the proper way of handling this? For example the code was extracting data from an excel file in order to format an HTML page. Now, I've convinced my employer to move their excel spreadsheet into a database to decrease redundancy, increase efficiency and yaddy yadda. Since I can now make logical queries that don't have to jump hoops to preform using the database I won't need the extra vbs files that originally manipulated the excel file. Technically I would be porting part of the existing code into the current new project. Since it already has it's own trunk, would it be advisable to combine the trunk of a different project to this one, and how would I do that exactly?? SO I guess my tree would look like this, and I haven't seen examples of software branching that resemble this inverted tree before so I'm wondering what the norm for a situation like this?

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  • How can I make an infinite cave using stage3d?

    - by ifree
    I want to make an infinite cave in my 3d game using flash stage3d. But I got no idea about how to build that cave. Can anyone can give me some solution or hint? update: I've tried agal fragment shader like squeae tunnel in shader toy code: var fragmentProgramCode:String = AGALUtils.build() .mov("ft0","v0") .div("ft1","ft0.xy","fc3.xy") .mul("ft2","fc6.x","ft1") .sub("ft3","ft2","fc5.x")//vec2 p = -1.0 + 2.0 * gl_FragCoord.xy / resolution.xy; .mul("ft1","ft3.x","ft3.x") .mul("ft2","ft3.y","ft3.y") .pow("ft4","ft1","fc6.z")//float r = pow( pow(p.x*p.x,16.0) + pow(p.y*p.y,16.0), 1.0/32.0 ); .pow("ft5","ft2","fc6.z") .add("ft1","ft4","ft5") .pow("ft4","ft1","fc6.w") .mov("ft5","fc5")//uv .sub("ft1","fc7.x","ft4") .add("ft5.x","fc7.x","ft1")//uv.x = .5*time + 0.5/r; .mov("ft6","fc0")//for atan .atan2("ft5.y","ft3.y","ft3.x",new <String>["fc7.y","fc5.x","fc7.z","fc7.w","fc8.x","fc8.y","fc8.z","fc8.w","fc9.x","fc9.y"],"ft6") .tex("ft0","ft5","fs0","repeat","linear","nomip")//tex .mul("ft1","ft4","ft4") .mul("ft2","ft1","ft4")//r*r*r .mul("ft1","ft0.xyz","ft2") .mov("ft0.w","fc5.x") .mov("oc","ft1").toString() it can only apply one material,but my project requires different types of material (like floor,ceilling). so ,I create a 3d model Is there anyway to make that 3d model render like "infinity cave"? use agal to make each side of cave's texture move? thanks for your help

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  • How do I render only part of a texture to a point sprite in OpenGL ES for Android?

    - by nbolton
    Using the libgdx framework, I've figured out how to render a texture to a point sprite. The problem is, it renders the entire texture to the point sprite, where I only want a small part of it (since it's an isometric tile image). Here's a snippet from some demo code I wrote... create() { renderer = new ImmediateModeRenderer(); tiles = Gdx.graphics.newTexture( Gdx.files.internal("data/tiles2.png"), TextureFilter.MipMap, TextureFilter.Linear, TextureWrap.ClampToEdge, TextureWrap.ClampToEdge); Gdx.gl.glClearColor(0.6f, 0.7f, 0.9f, 1); Gdx.gl.glEnable(GL10.GL_TEXTURE_2D); Gdx.gl.glEnable(GL11.GL_POINT_SPRITE_OES); Gdx.gl11.glTexEnvi( GL11.GL_POINT_SPRITE_OES, GL11.GL_COORD_REPLACE_OES, GL11.GL_TRUE); Gdx.gl10.glPointSize(s); tiles.bind(); } render() { Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); renderer.begin(GL10.GL_POINTS); // render 3 point sprites at various 3d points renderer.vertex(-.1f, 0, -.1f); renderer.vertex(0, 0, 0); renderer.vertex(.1f, 0, .1f); // ... more vertices here if needed (one for each sprite) ... renderer.end(); }

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  • Physics not synchronizing correctly over the network when using Bullet

    - by Lucas
    I'm trying to implement a client/server physics system using Bullet however I'm having problems getting things to sync up. I've implemented a custom motion state which reads and write the transform from my game objects and it works locally but I've tried two different approaches for networked games: Dynamic objects on the client that are also on the server (eg not random debris and other unimportant stuff) are made kinematic. This works correctly but the objects don't move very smoothly Objects are dynamic on both but after each message from the server that the object has moved I set the linear and angular velocity to the values from the server and call btRigidBody::proceedToTransform with the transform on the server. I also call btCollisionObject::activate(true); to force the object to update. My intent with method 2 was to basically do method 1 but hijacking Bullet to do a poor-man's prediction instead of doing my own to smooth out method 1, but this doesn't seem to work (for reasons that are not 100% clear to me even stepping through Bullet) and the objects sometimes end up in different places. Am I heading in the right direction? Bullet seems to have it's own interpolation code built-in. Can that help me make method 1 work better? Or is my method 2 code not working because I am accidentally stomping that?

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  • Applications: Some more marble fun!

    - by TechTwaddle
    Well, yesterday night I was watching a tutorial on XNA when I came across this neat little trick. It was a simple XNA application with a Windows Phone logo in it and whenever the user clicked on the device the logo would move towards the click point, and I couldn't resist experimenting with the marble (; The code is written in C# using CF3.5. Here is a video of the demo,   You probably noticed that the motion of the marble towards the click point (destination) is not linear. The marble starts off with a high velocity and slows down as it reaches its destination. This is achieved by making the speed of the marble a function of the distance between marble's current position and the destination, so as the marble approaches the destination point, the distance between them reduces and so does the speed, until it becomes zero. More on the code and the logic behind it in the next post. What I'd like to do next is, instead of making the marble stop at the click point, it should continue to move beyond it, bounce around the screen a few times and eventually come to a stop after a while. Let's see how that goes.

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  • Happy Tau Day! (Or: How Some Mathematicians Think We Should Retire Pi) [Video]

    - by Jason Fitzpatrick
    When you were in school you learned all about Pi and its relationship to circles and turn-based geometry. Some mathematicians are rallying for a new lesson, on about Tau. Michael Hartl is a mathematician on a mission, a mission to get people away from using Pi and to start using Tau. His manifesto opens: Welcome to The Tau Manifesto. This manifesto is dedicated to one of the most important numbers in mathematics, perhaps the most important: the circle constant relating the circumference of a circle to its linear dimension. For millennia, the circle has been considered the most perfect of shapes, and the circle constant captures the geometry of the circle in a single number. Of course, the traditional choice of circle constant is p—but, as mathematician Bob Palais notes in his delightful article “p Is Wrong!”,1 p is wrong. It’s time to set things right. Why is Pi wrong? Among the arguments is that Tau is the ration of a circumference to the radius of a circle and defining circles by their radius is more natural and that Pi is a 2-factor number but with Tau everything is based of a single unit–three quarters of a turn around a Tau-defined circle is simply three quarters of a Tau radian. Watch the video above to see the Tau sequence (which begins 6.2831853071…) turned into a musical composition. For more information about Tau hit up the link below to read the manifesto. The Tau Manifesto [TauDay] HTG Explains: Photography with Film-Based CamerasHow to Clean Your Dirty Smartphone (Without Breaking Something)What is a Histogram, and How Can I Use it to Improve My Photos?

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  • Logarithmic spacing of FFT subbands

    - by Mykel Stone
    I'm trying to do the examples within the GameDev.net Beat Detection article ( http://archive.gamedev.net/archive/reference/programming/features/beatdetection/index.html ) I have no issue with performing a FFT and getting the frequency data and doing most of the article. I'm running into trouble though in the section 2.B, Enhancements and beat decision factors. in this section the author gives 3 equations numbered R10-R12 to be used to determine how many bins go into each subband: R10 - Linear increase of the width of the subband with its index R11 - We can choose for example the width of the first subband R12 - The sum of all the widths must not exceed 1024 He says the following in the article: "Once you have equations (R11) and (R12) it is fairly easy to extract 'a' and 'b', and thus to find the law of the 'wi'. This calculus of 'a' and 'b' must be made manually and 'a' and 'b' defined as constants in the source; indeed they do not vary during the song." However, I cannot seem to understand how these values are calculated...I'm probably missing something simple, but learning fourier analysis in a couple of weeks has left me Decimated-in-Mind and I cannot seem to see it.

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  • Thematic map contd.

    - by jsharma
    The previous post (creating a thematic map) described the use of an advanced style (color ranged-bucket style). The bucket style definition object has an attribute ('classification') which specifies the data classification scheme to use. It's values can be one of {'equal', 'quantile', 'logarithmic', 'custom'}. We use logarithmic in the previous example. Here we'll describe how to use a custom algorithm for classification. Specifically the Jenks Natural Breaks algorithm. We'll use the Javascript implementation in geostats.js The sample code above needs a few changes which are listed below. Include the geostats.js file after or before including oraclemapsv2.js <script src="geostats.js"></script> Modify the bucket style definition to use custom classification Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}    bucketStyleDef = {       numClasses : colorSeries[colorName].classes,       classification: 'custom', //'logarithmic',  // use a logarithmic scale       algorithm: jenksFromGeostats,       styles: theStyles,       gradient:  useGradient? 'linear' : 'off'     }; The function, which implements the custom classification scheme, is specified as the algorithm attribute value. It must accept two input parameters, an array of OM.feature and the name of the feature attribute (e.g. TOTPOP) to use in the classification, and must return an array of buckets (i.e. an array of or OM.style.Bucket  or OM.style.RangedBucket in this case). However the algorithm also needs to know the number of classes (i.e. the number of buckets to create). So we use a global to pass that info in. (Note: This bug/oversight will be fixed and the custom algorithm will be passed 3 parameters: the features array, attribute name, and number of classes). So createBucketColorStyle() has the following changes Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} var numClasses ; function createBucketColorStyle( colorName, colorSeries, rangeName, useGradient) {    var theBucketStyle;    var bucketStyleDef;    var theStyles = [];    //var numClasses ; numClasses = colorSeries[colorName].classes; ... and the function jenksFromGeostats is defined as Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} function jenksFromGeostats(featureArray, columnName) {    var items = [] ; // array of attribute values to be classified    $.each(featureArray, function(i, feature) {         items.push(parseFloat(feature.getAttributeValue(columnName)));    });    // create the geostats object    var theSeries = new geostats(items);    // call getJenks which returns an array of bounds    var theClasses = theSeries.getJenks(numClasses);    if(theClasses)    {     theClasses[theClasses.length-1]=parseFloat(theClasses[theClasses.length-1])+1;    }    else    {     alert(' empty result from getJenks');    }    var theBuckets = [], aBucket=null ;    for(var k=0; k<numClasses; k++)    {             aBucket = new OM.style.RangedBucket(             {low:parseFloat(theClasses[k]),               high:parseFloat(theClasses[k+1])             });             theBuckets.push(aBucket);     }     return theBuckets; } A screenshot of the resulting map with 5 classes is shown below. It is also possible to simply create the buckets and supply them when defining the Bucket style instead of specifying the function (algorithm). In that case the bucket style definition object would be    bucketStyleDef = {      numClasses : colorSeries[colorName].classes,      classification: 'custom',        buckets: theBuckets, //since we are supplying all the buckets      styles: theStyles,      gradient:  useGradient? 'linear' : 'off'    };

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  • How to re-add RAID-10 dropped drive?

    - by thiesdiggity
    I have a problem that I can't seem to solve. We have a Ubuntu server setup with RAID-10 and two of the drives dropped out of the array. When I try to re-add them using the following command: mdadm --manage --re-add /dev/md2 /dev/sdc1 I get the following error message: mdadm: Cannot open /dev/sdc1: Device or resource busy When I do a "cat /proc/mdstat" I get the following: Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [r$ md2 : active raid10 sdb1[0] sdd1[3] 1953519872 blocks 64K chunks 2 near-copies [4/2] [U__U] md1 : active raid1 sda2[0] sdc2[1] 468853696 blocks [2/2] [UU] md0 : active raid1 sda1[0] sdc1[1] 19530688 blocks [2/2] [UU] unused devices: <none> When I run "/sbin/mdadm --detail /dev/md2" I get the following: /dev/md2: Version : 00.90 Creation Time : Mon Sep 5 23:41:13 2011 Raid Level : raid10 Array Size : 1953519872 (1863.02 GiB 2000.40 GB) Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) Raid Devices : 4 Total Devices : 2 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Thu Oct 25 09:25:08 2012 State : active, degraded Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Layout : near=2, far=1 Chunk Size : 64K UUID : c6d87d27:aeefcb2e:d4453e2e:0b7266cb Events : 0.6688691 Number Major Minor RaidDevice State 0 8 17 0 active sync /dev/sdb1 1 0 0 1 removed 2 0 0 2 removed 3 8 49 3 active sync /dev/sdd1 Output of df -h is: Filesystem Size Used Avail Use% Mounted on /dev/md1 441G 2.0G 416G 1% / none 32G 236K 32G 1% /dev tmpfs 32G 0 32G 0% /dev/shm none 32G 112K 32G 1% /var/run none 32G 0 32G 0% /var/lock none 32G 0 32G 0% /lib/init/rw tmpfs 64G 215M 63G 1% /mnt/vmware none 441G 2.0G 416G 1% /var/lib/ureadahead/debugfs /dev/mapper/RAID10VG-RAID10LV 1.8T 139G 1.6T 8% /mnt/RAID10 When I do a "fdisk -l" I can see all the drives needed for the RAID-10. The RAID-10 is part of the /dev/mapper, could that be the reason why the device is coming back as busy? Anyone have any suggestions on what I can try to get the drives back into the array? Any help would be greatly appreciated. Thanks!

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  • Alternative to NV Occlusion Query - getting the number of fragments which passed the depth test

    - by Etan
    In "modern" environments, the "NV Occlusion Query" extension provide a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension is not available. What is the most performant approach to implement a similar behaviour in the fragment shader? Some of my ideas: Render the object completely in white, then count all the colors together using a two-pass shader where first a vertical line is rendered and for each fragment the shader computes the sum over the whole row. Then, a single vertex is rendered whose fragment sums all the partial sums of the first pass. Doesn't seem to be very efficient. Render the object completely in white over a black background. Downsample recursively, abusing the hardware linear interpolation between textures until being at a reasonably small resolution. This leads to fragments which have a greyscale level depending on the number of white pixels where in their corresponding region. Is this even accurate enough? ... ?

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  • Could someone explain why my world reconstructed from depth position is incorrect?

    - by yuumei
    I am attempting to reconstruct the world position in the fragment shader from a depth texture. I pass in the 8 frustum points in world space and interpolate them across fragments and then interpolate from near to far by the depth: highp float depth = (2.0 * CameraPlanes.x) / (CameraPlanes.y + CameraPlanes.x - texture( depthTexture, textureCoord ).x * (CameraPlanes.y - CameraPlanes.x)); // Reconstruct the world position from the linear depth highp vec3 world = mix( nearWorldPos, farWorldPos, depth ); CameraPlanes.x is the near plane CameraPlanes.y is the far. Assuming that my frustum positions are correct, and my depth looks correct, why is my world position wrong? (My depth texture is of format GL_DEPTH_COMPONENT32F if that matters) Thanks! :D Update: Screenshot of world position http://imgur.com/sSlHd So you can see it looks nearly correct. However as the camera moves, the colours (positions) change, which they shouldnt. I can get this to work, if I do the following: Write this into the depth attachment in the previous pass: gl_FragDepth = gl_FragCoord.z / gl_FragCoord.w / CameraPlanes.y; and then read the depth texture like so: depth = texture( depthTexture, textureCoord ).x However this will kill the hardware z buffer optimizations.

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  • What is logical cohesion, and why is it bad or undesirable?

    - by Matt Fenwick
    From the c2wiki page on coupling & cohesion: Cohesion (interdependency within module) strength/level names : (from worse to better, high cohesion is good) Coincidental Cohesion : (Worst) Module elements are unrelated Logical Cohesion : Elements perform similar activities as selected from outside module, i.e. by a flag that selects operation to perform (see also CommandObject). i.e. body of function is one huge if-else/switch on operation flag Temporal Cohesion : operations related only by general time performed (i.e. initialization() or FatalErrorShutdown?()) Procedural Cohesion : Elements involved in different but sequential activities, each on different data (usually could be trivially split into multiple modules along linear sequence boundaries) Communicational Cohesion : unrelated operations except need same data or input Sequential Cohesion : operations on same data in significant order; output from one function is input to next (pipeline) Informational Cohesion: a module performs a number of actions, each with its own entry point, with independent code for each action, all performed on the same data structure. Essentially an implementation of an abstract data type. i.e. define structure of sales_region_table and its operators: init_table(), update_table(), print_table() Functional Cohesion : all elements contribute to a single, well-defined task, i.e. a function that performs exactly one operation get_engine_temperature(), add_sales_tax() (emphasis mine). I don't fully understand the definition of logical cohesion. My questions are: what is logical cohesion? Why does it get such a bad rap (2nd worst kind of cohesion)?

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  • Are there design patterns or generalised approaches for particle simulations?

    - by romeovs
    I'm working on a project (for college) in C++. The goal is to write a program that can more or less simulate a beam of particles flying trough the LHC synchrotron. Not wanting to rush into things, me and my team are thinking about how to implement this and I was wondering if there are general design patterns that are used to solve this kind of problem. The general approach we came up with so far is the following: there is a World that holds all objects you can add objects to this world such as Particle, Dipole and Quadrupole time is cut up into discrete steps, and at each point in time, for each Particle the magnetic and electric forces that each object in the World generates are calculated and summed up (luckily electro-magnetism is linear). each Particle moves accordingly (using a simple estimation approach to solve the differential movement equations) save the Particle positions repeat This seems a good approach but, for instance, it is hard to take into account symmetries that might be present (such as the magnetic field of each Quadrupole) and is this thus suboptimal. To take into account such symmetries as that of the Quadrupole field, it would be much easier to (also) make space discrete and somehow store form of the Quadrupole field somewhere. (Since 2532 or so Quadrupoles are stored this should lead to a massive gain of performance, not having to recalculate each Quadrupole field) So, are there any design patterns? Is the World-approach feasible or is it old-fashioned, bad programming? What about symmetry, how is that generally taken into acount?

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  • What is the R Language?

    - by TATWORTH
    I encountered the R Language recently with O'Reilly books and while from the context I knew it was a language for dealing with statistics, doing a web search for the support web site was futile. However I have now located the web site and it is at http://www.r-project.org/R is a free language available for a number of platforms including windows. CRAN mirrors are available at a number of locations worldwide.Here is the official description:"R is a language and environment for statistical computing and graphics. It is a GNU project which is similar to the S language and environment which was developed at Bell Laboratories (formerly AT&T, now Lucent Technologies) by John Chambers and colleagues. R can be considered as a different implementation of S. There are some important differences, but much code written for S runs unaltered under R. R provides a wide variety of statistical (linear and nonlinear modelling, classical statistical tests, time-series analysis, classification, clustering, ...) and graphical techniques, and is highly extensible. The S language is often the vehicle of choice for research in statistical methodology, and R provides an Open Source route to participation in that activity. One of R's strengths is the ease with which well-designed publication-quality plots can be produced, including mathematical symbols and formulae where needed. Great care has been taken over the defaults for the minor design choices in graphics, but the user retains full control. R is available as Free Software under the terms of the Free Software Foundation's GNU General Public License in source code form. It compiles and runs on a wide variety of UNIX platforms and similar systems (including FreeBSD and Linux), Windows and MacOS."

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  • Effective and simple matching for 2 unequal small-scale point sets

    - by Pavlo Dyban
    I need to match two sets of 3D points, however the number of points in each set can be different. It seems that most algorithms are designed to align images and trimmed to work with hundreds of thousands of points. My case are 50 to 150 points in each of the two sets. So far I have acquainted myself with Iterative Closest Point and Procrustes Matching algorithms. Implementing Procrustes algorithms seems like a total overkill for this small quantity. ICP has many implementations, but I haven't found any readily implemented version accounting for the so-called "outliers" - points without a matching pair. Besides the implementation expense, algorithms like Fractional and Sparse ICP use some statistics information to cancel points that are considered outliers. For series with 50 to 150 points statistic measures are often biased or statistic significance criteria are not met. I know of Assignment Problem in linear optimization, but it is not suitable for cases with unequal sets of points. Are there other, small-scale algorithms that solve the problem of matching 2 point sets? I am looking for algorithm names, scientific papers or C++ implementations. I need some hints to know where to start my search.

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  • Tail-recursive implementation of take-while

    - by Giorgio
    I am trying to write a tail-recursive implementation of the function take-while in Scheme (but this exercise can be done in another language as well). My first attempt was (define (take-while p xs) (if (or (null? xs) (not (p (car xs)))) '() (cons (car xs) (take-while p (cdr xs))))) which works correctly but is not tail-recursive. My next attempt was (define (take-while-tr p xs) (let loop ((acc '()) (ys xs)) (if (or (null? ys) (not (p (car ys)))) (reverse acc) (loop (cons (car ys) acc) (cdr ys))))) which is tail recursive but needs a call to reverse as a last step in order to return the result list in the proper order. I cannot come up with a solution that is tail-recursive, does not use reverse, only uses lists as data structure (using a functional data structure like a Haskell's sequence which allows to append elements is not an option), has complexity linear in the size of the prefix, or at least does not have quadratic complexity (thanks to delnan for pointing this out). Is there an alternative solution satisfying all the properties above? My intuition tells me that it is impossible to accumulate the prefix of a list in a tail-recursive fashion while maintaining the original order between the elements (i.e. without the need of using reverse to adjust the result) but I am not able to prove this. Note The solution using reverse satisfies conditions 1, 3, 4.

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  • FP for simulation and modelling

    - by heaptobesquare
    I'm about to start a simulation/modelling project. I already know that OOP is used for this kind of projects. However, studying Haskell made me consider using the FP paradigm for modelling a system of components. Let me elaborate: Let's say I have a component of type A, characterised by a set of data (a parameter like temperature or pressure,a PDE and some boundary conditions,etc.) and a component of type B, characterised by a different set of data(different or same parameter, different PDE and boundary conditions). Let's also assume that the functions/methods that are going to be applied on each component are the same (a Galerkin method for example). If I were to use an OOP approach, I would create two objects that would encapsulate each type's data, the methods for solving the PDE(inheritance would be used here for code reuse) and the solution to the PDE. On the other hand, if I were to use an FP approach, each component would be broken down to data parts and the functions that would act upon the data in order to get the solution for the PDE. This approach seems simpler to me assuming that linear operations on data would be trivial and that the parameters are constant. What if the parameters are not constant(for example, temperature increases suddenly and therefore cannot be immutable)? In OOP, the object's (mutable) state can be used. I know that Haskell has Monads for that. To conclude, would implementing the FP approach be actually simpler,less time consuming and easier to manage (add a different type of component or new method to solve the pde) compared to the OOP one? I come from a C++/Fortran background, plus I'm not a professional programmer, so correct me on anything that I've got wrong.

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