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  • Handling early/late/dropped packets for interpolation in a 3D multiplayer game

    - by Ben Cracknell
    I'm working on a multiplayer game that for the purposes of this question, is most similar to Team Fortress. Each network data packet will contain the 3D position of the target moving object. (this object could be another player) The packets are sent on a fixed interval, and linear interpolation will be used to smooth the transition between packets. Under normal circumstances, interpolation will occur between the second-to-last packet, and the last packet received. The linear interpolation algorithm is the same as this post: Interpolating positions in a multiplayer game I have the same issue as in that post, but the answers don't seem like they will work in my situation. Consider the following scenario: Normal packet timing, everything is okay The next expected packet is late. That's okay, we'll just extrapolate based on previous positions The late packet eventually arrives with corrections to our extrapolation. Now what do we do with its information? The answers on the above post suggest we should just interpolate to this new packet's position, but that would not work at all. If we have already extrapolated past that point in time, moving back would cause rubber-banding. The issue is similar in the case of an early or dropped packet. So I believe what I am looking for is some way to smoothly deal with new information in an ongoing interpolation/extrapolation process. Since I might be moving on to quadratic or even cubic interpolation, it would be great if the same solutiuon could be applied to those as well.

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  • Beginners Guide to Client Application Services

    - by mbcrump
    What is it? Client application services make it easy for you to create Windows-based applications that use the ASP.NET AJAX login, roles, and profile application services included in the Microsoft ASP.NET 2.0 AJAX Extensions. These services enable multiple Web and Windows-based applications to share user information and user-management functionality from a single server.   What can you do with it? Authenticate a user. You can use the authentication service to verify a user's identity. Determine the role or roles of an authenticated user. You can use the roles service to change the user interface of your application depending on the user's role. For example, you can provide additional features for users who are in an administrator role. Store and access per-user application settings located on the server. You can use the Web settings service (also known as the profile service) to share settings across multiple applications and locations. Client application services take advantage of the Web services extensibility model through client service providers that you can specify in your application configuration files. These service providers include offline functionality that uses a local cache for authentication, roles, and settings data when a network connection is unavailable. Give me an example of where I would use this! Sharing login and user role information between a Windows Form application and a ASP.NET application. How do I configure it? Click Here

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  • Events Driven Library XNA C#

    - by SchautDollar
    Language: C# w/ XNA Framework Relevant and Hopefully Helpful Background Info: I am making a library using the XNA framework for games I make with XNA. The Library has a folder(Namespace) dedication to the GUI. The GUI Controls inherit a base class hooked with the appropriate Interfaces. After a control is made, the programmer can hook the control with a "Frame" or "Module" that will tell the controls when to update and draw with an event. To make a "Frame" or "Module", you would inherit a class with the details coded in. (Kind of how win forms does it.) My reason for doing this is to simplify the process of creating menus with intractable controls. The only way I could think of for making the events for all the controls to function without being class specific would be to typecast a control to an object and typecast it back. (As I have read, this can be terribly inefficient.) Problem: Unfortunately, after I have implemented interfaces into the base classes and changed public delegate void ClickedHandler(BaseControl cntrl); to public delegate void ClickedHandler(Object cntrl, EventArgs e); my game has decreased in performance. This performance could be how I am firing the events, as what happens is the one menu will start fine, but then slowly but surely will freeze up. Every other frame works just fine, I just think it has something to do with the events and... that is why I am asking about them. Question: Is there a better more industry way of dealing with GUI Libraries other then using and implementing Events? Goal: To create a reusable feature rich XNA Control Library implementing performance enhancing standards and so on. Thank-you very much for taking your time to read this. I also hope this will help others possibly facing what I am facing right now.

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  • ArchBeat Link-o-Rama for 101/10/2011

    - by Bob Rhubart
    All day, all architecture. Oracle Technology Network Architect Day - Phoenix, AZ - Dec 14. Free registration. Spend the day with your peers learning from Oracle experts in Cloud Computing, Engineered Systems, Oracle WebLogic, Oracle Coherence, Application-Driven Virtualization, and more. Registration is free, but seating is limited. Register now! Data Integration - Bad data is really the monster | Bikram Sinha "Bad data can cause huge operational failure and cost millions of dollars in terms of time and resources to clean up and validate data across multiple participating systems," says Bikram Sinha. Changing a navigation model on a page in WebCenter | Edwin Biemond Another illustrated how-to from Oracle ACE Edwin Biemond. Why do I need an Authenticator when I have an Identity Asserter? | Chris Johnson Chris Johnson responds to a user question. OOW: The Most Important Thing | Floyd Teter Oracle ACE Director Floyd Teter explains why he sees "the inclusion of Fusion Applications CRM and HCM in the Oracle Public Cloud" as the most important news to come out of Oracle OpenWorld 2011. Oracle Releases Oracle Solaris 11 | Gokhan Atil Atil offers an overview of some of the "key points" of the new Solaris 11 release. SOA Development Virtual Developer Day (On Demand) You won't get the hands-on experience available in the live event, but if you will learn learn how a SOA approach can be implemented, whether starting afresh with new services or reusing existing services. Webcast: Maximum Availability on Private Clouds - Nov 10 - 10am PT/ 1pm ET Featuring Margaret Hamburger (Director, Product Marketing, Oracle) and Joe Meeks (Director, Product Management, Oracle). Should Enterprise Architecture Teams Be More Focused on Innovation? | Richard Seroter Richard Seroter looks answers among opinions offered by Forrester analyst Brian Hopkins and Jude Umeh of CapGemini.

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  • How Service Component Architecture (SCA) Can Be Incorporated Into Existing Enterprise Systems

    After viewing Rob High’s presentation “The SOA Component Model” hosted on InfoQ.com, I can foresee how Service Component Architecture (SCA) can be incorporated in to an existing enterprise. According to IBM’s DeveloperWorks website, SCA is a set of conditions which outline a model for constructing applications/systems using a Service-Oriented Architecture (SOA). In addition, SCA builds on open standards such as Web services. In the future, I can easily see how some large IT shops could potently divide development teams or work groups up into Component/Data Object Groups, and Standard Development Groups. The Component/Data Object Group would only work on creating and maintaining components that are reused throughout the entire enterprise. The Standard Development Group would work on new and existing projects that incorporate the use of various components to accomplish various business tasks. In my opinion the incorporation of SCA in to any IT department will initially slow down the number of new features developed due to the time needed to create the new and loosely-coupled components. However once a company becomes more mature in its SCA process then the number of program features developed will greatly increase. I feel this is due to the fact that the loosely-coupled components needed in order to add the new features will already be built and ready to incorporate into any new development feature request. References: BEA Systems, Cape Clear Software, IBM, Interface21, IONA Technologies PLC, Oracle, Primeton Technologies Ltd, Progress Software, Red Hat Inc., Rogue Wave Software, SAP AG, Siebel Systems, Software AG, Sun Microsystems, Sybase, TIBCO Software Inc. (2006). Service Component Architecture. Retrieved 11 27, 2011, from DeveloperWorks: http://www.ibm.com/developerworks/library/specification/ws-sca/ High, R. (2007). The SOA Component Model. Retrieved 11 26, 2011, from InfoQ: http://www.infoq.com/presentations/rob-high-sca-sdo-soa-programming-model

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  • Having trouble with projection matrix, need help

    - by Mr.UNOwen
    I'm having trouble with what appears to be the projection matrix. Given a wide enough of a screen, when a cube is on the left and right most edge, the left or right wall will appear stretched to the point that the front face is 1/10 the width of the side. So I do update the screen ratio along with the projection matrix and view port on screen resize, am I safe to assume all the trouble is from the matrix class? Also the cube follows the mouse, but it's only vertically aligned and ahead of the mouse when going left or right from the center of the screen. Perspective function call: * setPerspective * * @param fov: angle in radians * @param aspect: screen ratio w/h * @param near: near distance * @param far: far distance **/ void APCamera::setPerspective(GMFloat_t fov, GMFloat_t aspect, GMFloat_t near, GMFloat_t far) { GMFloat_t difZ = near - far; GMFloat_t *data; mProjection->clear(); //set to identity matrix data = mProjection->getData(); GMFloat_t v = 1.0f / tan(fov / 2.0f); data[_AP_MAA] = v / aspect; data[_AP_MBB] = v; data[_AP_MCC] = (far + near) / difZ; data[_AP_MCD] = -1.0f; data[_AP_MDD] = 0.0f; data[_AP_MDC] = 2.0f * far * near/ difZ; mRatio = aspect; mInvProjOutdated = true; mIsPerspective = true; } and... #define _AP_MAA 0 #define _AP_MAB 1 #define _AP_MAC 2 #define _AP_MAD 3 #define _AP_MBA 4 #define _AP_MBB 5 #define _AP_MBC 6 #define _AP_MBD 7 #define _AP_MCA 8 #define _AP_MCB 9 #define _AP_MCC 10 #define _AP_MCD 11 #define _AP_MDA 12 #define _AP_MDB 13 #define _AP_MDC 14 #define _AP_MDD 15

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  • What's a good entity hierarchy for a 2D game?

    - by futlib
    I'm in the process of building a new 2D game out of some code I wrote a while ago. The object hierarchy for entities is like this: Scene (e.g. MainMenu): Contains multiple entities and delegates update()/draw() to each Entity: Base class for all things in a scene (e.g. MenuItem or Alien) Sprite: Base class for all entities that just draw a texture, i.e. don't have their own drawing logic Does it make sense to split up entities and sprites up like that? I think in a 2D game, the terms entity and sprite are somewhat synonymous, right? But I do believe that I need some base class for entities that just draw a texture, as opposed to drawing themselves, to avoid duplication. Most entities are like that. One weird case is my Text class: It derives from Sprite, which accepts either the path of an image or an already loaded texture in its constructor. Text loads a texture in its constructor and passes that to Sprite. Can you outline a design that makes more sense? Or point me to a good object-oriented reference code base for a 2D game? I could only find 3D engine code bases of decent code quality, e.g. Doom 3 and HPL1Engine.

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  • Initializing OpenFeint for Android outside the main Application

    - by Ef Es
    I am trying to create a generic C++ bridge to use OpenFeint with Cocos2d-x, which is supposed to be just "add and run" but I am finding problems. OpenFeint is very exquisite when initializing, it requires a Context parameter that MUST be the main Application, in the onCreate method, never the constructor. Also, the main Apps name must be edited into the manifest. I am trying to fix this. So far I have tried to create a new Application that calls my Application to test if just the type is needed, but you do really need the main Android application. I also tried using a handler for a static initialization but I found pretty much the same problem. Has anybody been able to do it? This is my working-but-not-as-intended code snippet public class DerpHurr extends Application{ @Override public void onCreate() { super.onCreate(); initializeOpenFeint("TestApp", "edthedthedthedth", "aeyaetyet", "65462"); } public void initializeOpenFeint(String appname, String key, String secret, String id){ Map<String, Object> options = new HashMap<String, Object>(); options.put(OpenFeintSettings.SettingCloudStorageCompressionStrategy, OpenFeintSettings.CloudStorageCompressionStrategyDefault); OpenFeintSettings settings = new OpenFeintSettings(appname, key, secret, id, options); //RIGHT HERE OpenFeint.initialize(***this***, settings, new OpenFeintDelegate() { }); System.out.println("OpenFeint Started"); } } Manifest <application android:debuggable="true" android:label="@string/app_name" android:name=".DerpHurr">

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  • How do I initialize a Scala map with more than 4 initial elements in Java?

    - by GlenPeterson
    For 4 or fewer elements, something like this works (or at least compiles): import scala.collection.immutable.Map; Map<String,String> HAI_MAP = new Map4<>("Hello", "World", "Happy", "Birthday", "Merry", "XMas", "Bye", "For Now"); For a 5th element I could do this: Map<String,String> b = HAI_MAP.$plus(new Tuple2<>("Later", "Aligator")); But I want to know how to initialize an immutable map with 5 or more elements and I'm flailing in Type-hell. Partial Solution I thought I'd figure this out quickly by compiling what I wanted in Scala, then decompiling the resultant class files. Here's the scala: object JavaMapTest { def main(args: Array[String]) = { val HAI_MAP = Map(("Hello", "World"), ("Happy", "Birthday"), ("Merry", "XMas"), ("Bye", "For Now"), ("Later", "Aligator")) println("My map is: " + HAI_MAP) } } But the decompiler gave me something that has two periods in a row and thus won't compile (I don't think this is valid Java): scala.collection.immutable.Map HAI_MAP = (scala.collection.immutable.Map) scala.Predef..MODULE$.Map().apply(scala.Predef..MODULE$.wrapRefArray( scala.Predef.wrapRefArray( (Object[])new Tuple2[] { new Tuple2("Hello", "World"), new Tuple2("Happy", "Birthday"), new Tuple2("Merry", "XMas"), new Tuple2("Bye", "For Now"), new Tuple2("Later", "Aligator") })); I'm really baffled by the two periods in this: scala.Predef..MODULE$ I asked about it on #java on Freenode and they said the .. looked like a decompiler bug. It doesn't seem to want to compile, so I think they are probably right. I'm running into it when I try to browse interfaces in IntelliJ and am just generally lost. Based on my experimentation, the following is valid: Tuple2[] x = new Tuple2[] { new Tuple2<String,String>("Hello", "World"), new Tuple2<String,String>("Happy", "Birthday"), new Tuple2<String,String>("Merry", "XMas"), new Tuple2<String,String>("Bye", "For Now"), new Tuple2<String,String>("Later", "Aligator") }; scala.collection.mutable.WrappedArray<Tuple2> y = scala.Predef.wrapRefArray(x); There is even a WrappedArray.toMap() method but the types of the signature are complicated and I'm running into the double-period problem there too when I try to research the interfaces from Java.

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  • Dividing up spritesheet in Javascript

    - by hustlerinc
    I would like to implement an object for my spritesheets in Javascript. I'm very new to this language and game-developement so I dont really know how to do it. My guess is I set spritesize to 16, use that to divide as many times as it fits on the spritesheet and store this value as "spritesheet". Then a for(i=0;i<spritesheet.length;i++) loop running over the coordinates. Then tile = new Image(); and tile.src = spritesheet[i] to store the individual sprites based on their coordinates on the spritesheet. My problem is how could I loop trough the spritesheet and make an array of that? The result should be similar to: var tile = Array( "img/ground.png", "img/crate.png" ); If possible this would be done with one single object that i only access once, and the tile array would be stored for later reference. I couldn't find anything similar searching for "javascript spritesheet". Edit: I made a small prototype of what I'm after: function Sprite(){ this.size = 16; this.spritesheet = new Image(); this.spritesheet.src = 'img/spritesheet.png'; this.countX = this.spritesheet.width / 16; this.countY = this.spritesheet.height / 16; this.spriteCount = this.countX * this.countY; this.divide = function(){ for(i=0;i<this.spriteCount;i++){ // define spritesheet coordinates and store as tile[i] } } } Am I on the right track?

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  • Vertex fog producing black artifacts

    - by Nick
    I originally posted this question on the XNA forums but got no replies, so maybe someone here can help: I am rendering a textured model using the XNA BasicEffect. When I enable fog, the model outline is still visible as many small black dots when it should be "in the fog". Why is this happening? Here's what it looks like for me -- http://tinypic.com/r/fnh440/6 Here is a minimal example showing my problem: (the ship model that this example uses is from the chase camera sample on this site -- http://xbox.create.msdn.com/en-US/education/catalog/sample/chasecamera -- in case anyone wants to try it out ;)) public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Model model; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // TODO: use this.Content to load your game content here model = Content.Load<Model>("ship"); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect be in mesh.Effects) { be.EnableDefaultLighting(); be.FogEnabled = true; be.FogColor = Color.CornflowerBlue.ToVector3(); be.FogStart = 10; be.FogEnd = 30; } } } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here model.Draw(Matrix.Identity * Matrix.CreateScale(0.01f) * Matrix.CreateRotationY(3 * MathHelper.PiOver4), Matrix.CreateLookAt(new Vector3(0, 0, 30), Vector3.Zero, Vector3.Up), Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, 16f/9f, 1, 100)); base.Draw(gameTime); } }

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  • Issue While uploading a image to share point 2010 picture library.

    - by Gino Abraham
    I was trying to upload a image to my picture library using sharepoint client object model. I Used the code from the below blog to upload a file to my picture library. http://blogs.msdn.com/b/sridhara/archive/2010/03/12/uploading-files-using-client-object-model-in-sharepoint-2010.aspx The image got uploaded sucessfully. But when we took the relative url to update in a different list, we were getting empty image symbol. After a lot of analysis we figured out that the issue was with the file we uploaded. An image file which is of jpeg quality was uploaded to an application with giff extension. Try this. Copy a JPG file from net and save it to your file system. Change the extension of the file from jpg to giff. When you change the file extension the image quality remains same but it will open in picture viewers. Upload the file to your picture library. Once uploaded you will get the file listed as thumbail in your picture library. Click on the thumbnail image it will open up a page showing a larger image with file details. Now click either on the image or the file name hyper link, it will open up an empty page with default no image symbol. I wasted a lot of time on this figuring out the issue, so thought of sharing here. Hope this helps some one.

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  • ASP.NET Session Management

    - by geekrutherford
    Great article (a little old but still relevant) about the inner workings of session management in ASP.NET: Underpinnings of the Session State Management Implementation in ASP.NET.   Using StateServer and the BinaryFormatter serialization occuring caused me quite the headache over the last few days. Curiously, it appears the w3wp.exe process actually consumes more memory when utilizing StateServer and storing somewhat large and complex data types in session.   Users began experiencing Out Of Memory exceptions in the production environment. Looking at the stack trace it related to serialization using the BinaryFormatter. Using remote debugging against our QA server I noted that the code in the application functioned without issue. The exception occured outside the context of the application itself when the request had completed and the web server was trying to serialize session state into the StateServer.   The short term solution is switching back to the InProc method. Thus far this has proven to consume considerably less memory and has caused no issues. Long term the complex object stored in session will be off-loaded into a web service used to access the information directly from the database outside the context of the object used to encapsulate it.

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  • Question about separating game core engine from game graphics engine...

    - by Conrad Clark
    Suppose I have a SquareObject class, which implements IDrawable, an interface which contains the method void Draw(). I want to separate drawing logic itself from the game core engine. My main idea is to create a static class which is responsible to dispatch actions to the graphic engine. public static class DrawDispatcher<T> { private static Action<T> DrawAction = new Action<T>((ObjectToDraw)=>{}); public static void SetDrawAction(Action<T> action) { DrawAction = action; } public static void Dispatch(this T Obj) { DrawAction(Obj); } } public static class Extensions { public static void DispatchDraw<T>(this object Obj) { DrawDispatcher<T>.DispatchDraw((T)Obj); } } Then, on the core side: public class SquareObject: GameObject, IDrawable { #region Interface public void Draw() { this.DispatchDraw<SquareObject>(); } #endregion } And on the graphics side: public static class SquareRender{ //stuff here public static void Initialize(){ DrawDispatcher<SquareObject>.SetDrawAction((Square)=>{//my square rendering logic}); } } Do this "pattern" follow best practices? And a plus, I could easily change the render scheme of each object by changing the DispatchDraw parameter, as in: public class SuperSquareObject: GameObject, IDrawable { #region Interface public void Draw() { this.DispatchDraw<SquareObject>(); } #endregion } public class RedSquareObject: GameObject, IDrawable { #region Interface public void Draw() { this.DispatchDraw<RedSquareObject>(); } #endregion } RedSquareObject would have its own render method, but SuperSquareObject would render as a normal SquareObject I'm just asking because i do not want to reinvent the wheel, and there may be a design pattern similar (and better) to this that I may be not acknowledged of. Thanks in advance!

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  • How can I save state from script in a multithreaded engine?

    - by Peter Ren
    We are building a multithreaded game engine and we've encountered some problems as described below. The engine have 3 threads in total: script, render, and audio. Each frame, we update these 3 threads simultaneously. As these threads updating themselves, they produce some tasks and put them into a public storage area. As all the threads finish their update, each thread go and copy the tasks for themselves one by one. After all the threads finish their task copying, we make the threads process those tasks and update these threads simultaneously as described before. So this is the general idea of the task schedule part of our engine. Ok, well, all the task schedule part work well, but here's the problem: For the simplest, I'll take Camera as an example: local oldPos = camera:getPosition() -- ( 0, 0, 0 ) camera:setPosition( 1, 1, 1 ) -- Won't work now, cuz the render thread will process the task at the beginning of the next frame local newPos = camera:getPosition() -- Still ( 0, 0, 0 ) So that's the problem: If you intend to change a property of an object in another thread, you have to wait until that thread process this property-changing message. As a result, what you get from the object is still the information in the last frame. So, is there a way to solve this problem? Or are we build the task schedule part in a wrong way? Thanks for your answers :)

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  • How to handle multiple effect files in XNA

    - by Adam 'Pi' Burch
    So I'm using ModelMesh and it's built in Effects parameter to draw a mesh with some shaders I'm playing with. I have a simple GUI that lets me change these parameters to my heart's desire. My question is, how do I handle shaders that have unique parameters? For example, I want a 'shiny' parameter that affects shaders with Phong-type specular components, but for an environment mapping shader such a parameter doesn't make a lot of sense. How I have it right now is that every time I call the ModelMesh's Draw() function, I set all the Effect parameters as so foreach (ModelMesh m in model.Meshes) { if (isDrawBunny == true)//Slightly change the way the world matrix is calculated if using the bunny object, since it is not quite centered in object space { world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position + bunnyPositionTransform); } else //If not rendering the bunny, draw normally { world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position); } foreach (Effect e in m.Effects) { Matrix ViewProjection = camera.ViewMatrix * camera.ProjectionMatrix; e.Parameters["ViewProjection"].SetValue(ViewProjection); e.Parameters["World"].SetValue(world); e.Parameters["diffuseLightPosition"].SetValue(lightPositionW); e.Parameters["CameraPosition"].SetValue(camera.Position); e.Parameters["LightColor"].SetValue(lightColor); e.Parameters["MaterialColor"].SetValue(materialColor); e.Parameters["shininess"].SetValue(shininess); //e.Parameters //e.Parameters["normal"] } m.Draw(); Note the prescience of the example! The solutions I've thought of involve preloading all the shaders, and updating the unique parameters as needed. So my question is, is there a best practice I'm missing here? Is there a way to pull the parameters a given Effect needs from that Effect? Thank you all for your time!

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  • Keep 3d model facing the camera at all angles

    - by Sparky41
    I'm trying to keep a 3d plane facing the camera at all angles but while i have some success with this: Vector3 gunToCam = cam.cameraPosition - getWorld.Translation; Vector3 beamRight = Vector3.Cross(torpDirection, gunToCam); beamRight.Normalize(); Vector3 beamUp = Vector3.Cross(beamRight, torpDirection); shipeffect.beamWorld = Matrix.Identity; shipeffect.beamWorld.Forward = (torpDirection) * 1f; shipeffect.beamWorld.Right = beamRight; shipeffect.beamWorld.Up = beamUp; shipeffect.beamWorld.Translation = shipeffect.beamPosition; *Note: Logic not wrote by me i just found this rather useful It seems to only face the camera at certain angles. For example if i place the camera behind the plane you can see it that only Roll's around the axis like this: http://i.imgur.com/FOKLx.png (imagine if you are looking from behind where you have fired from. Any idea what to what the problem is (angles are not my specialty) shipeffect is an object that holds this class variables: public Texture2D altBeam; public Model beam; public Matrix beamWorld; public Matrix[] gunTransforms; public Vector3 beamPosition;

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  • Would it be a good idea to work on letting people add arrays of numbers in javascript?

    - by OneThreeSeven
    I am a very mathematically oriented programmer, and I happen to be doing a lot of java script these days. I am really disappointed in the math aspects of javascript: the Math object is almost a joke because it has so few methods you can't use ^ for exponentiation the + operator is very limited, you cant add array's of numbers or do scalar multiplication on arrays Now I have written some pretty basic extensions to the Math object and have considered writing a library of advanced Math features, amazingly there doesn't seem to be any sort of standard library already out even for calculus, although there is one for vectors and matricies I was able find. The notation for working with vectors and matricies is really bad when you can't use the + operator on arrays, and you cant do scalar multiplication. For example, here is a hideous expression for subtracting two vectors, A - B: Math.vectorAddition(A,Math.scalarMultiplication(-1,B)); I have been looking for some kind of open-source project to contribute to for awhile, and even though my C++ is a bit rusty I would very much like to get into the code for V8 engine and extend the + operator to work on arrays, to get scalar multiplication to work, and possibly to get the ^ operator to work for exponentiation. These things would greatly enhance the utility of any mathematical javascript framework. I really don't know how to get involved in something like the V8 engine other than download the code and start working on it. Of course I'm afraid that since V8 is chrome specific, that without browser cross-compatibility a fundamental change of this type is likely to be rejected for V8. I was hoping someone could either tell me why this is a bad idea, or else give me some pointers about how to proceed at this point to get some kind of approval to add these features. Thanks!

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  • Vernon's book Implementing DDD and modeling of underlying concepts

    - by EdvRusj
    Following questions all refer to examples presented in Implementing DDD In article we can see from Figure 6 that both BankingAccount and PayeeAccount represent the same underlying concept of Banking Account BA 1. On page 64 author gives an example of a publishing organization, where the life-cycle of a book goes through several stages ( proposing a book, editorial process, translation of the book ... ) and at each of those stages this book has a different definition. Each stage of the book is defined in a different Bounded Context, but do all these different definitions still represent the same underlying concept of a Book, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA? 2. a) I understand why User shouldn't exist in Collaboration Context ( CC ), but instead should be defined within Identity and Access Context IAC ( page 65 ). But still, do User ( IAC ), Moderator ( CC ), Author ( CC ),Owner ( CC ) and Participant ( CC ) all represent different aspects of the same underlying concept? b) If yes, then this means that CC contains several model elements ( Moderator, Author, Owner and Participant ), each representing different aspect of the same underlying concept ( just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA ). But isn't this considered a duplication of concepts ( Evan's book, page 339 ), since several model elements in CC represent the same underlying concept? c) If Moderator, Author ... don't represent the same underlying concept, then what underlying concept does each represent? 3. In an e-commerce system, the term Customer has multiple meanings ( page 49 ): When user is browsing the Catalog, Customer has different meaning than when user is placing an Order. But do these two different definitions of a Customer represent the same underlying concept, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA? thanks

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  • What's so bad about pointers in C++?

    - by Martin Beckett
    To continue the discussion in Why are pointers not recommended when coding with C++ Suppose you have a class that encapsulates objects which need some initialisation to be valid - like a network socket. // Blah manages some data and transmits it over a socket class socket; // forward declaration, so nice weak linkage. class blah { ... stuff TcpSocket *socket; } ~blah { // TcpSocket dtor handles disconnect delete socket; // or better, wrap it in a smart pointer } The ctor ensures that socket is marked NULL, then later in the code when I have the information to initialise the object. // initialising blah if ( !socket ) { // I know socket hasn't been created/connected // create it in a known initialised state and handle any errors // RAII is a good thing ! socket = new TcpSocket(ip,port); } // and when i actually need to use it if (socket) { // if socket exists then it must be connected and valid } This seems better than having the socket on the stack, having it created in some 'pending' state at program start and then having to continually check some isOK() or isConnected() function before every use. Additionally if TcpSocket ctor throws an exception it's a lot easier to handle at the point a Tcp connection is made rather than at program start. Obviously the socket is just an example, but I'm having a hard time thinking of when an encapsulated object with any sort of internal state shouldn't be created and initialised with new.

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  • Example of persisting an inheritance relationship using ORM

    - by Schemer
    I have some experience with OOP and RDBs, but very little exposure to web programming. I am trying to understand what non-trivial types of problems are solved by ORM. Of course, I am familiar with the need for data persistence, but I have never encountered a need for persisting relationships between objects, a situation which is indicated in many online articles about ORM. I am not asking about the process of persisting a POJO to a database and restoring it later. Nor am I asking about why ORM frameworks are useful -- or a pain in the butt -- for doing so. I am particularly interested in how the need arises to persist and restore relationships between objects. In various documentation, I have seen many examples of persisting POJOs to a database, but the examples have all been for only very simple objects that are essentially nothing more than records anyway: a constructor, some private fields, and getter/setter methods. The motivation for persisting such an "object-record" seems obvious and trivial. This example: Hibernate ORM Tutorial offers such an example, but goes on to discuss mismatch issues of granularity, inheritance, identity, associations, and navigation that are not motivated by the example. If someone could offer a toy example of an instance where, say, the need arises to persist an inheritance relationship, I would be grateful. This might be blindingly obvious for anyone who has already encountered this situation but I have not and a great deal of searching and reading have not turned up any examples.

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  • What is the best type of c# timer to use with an Unity game that uses many timers simultaneously?

    - by Kyle Seidlitz
    I am developing a stand-alone 3d game in Unity that will have anywhere from 1 to 200 timers running simultaneously. For this game timer durations will range from 5 minutes to 4 days. There will not be any countdown displays or any UI for the timers. An object will be selected, a menu choice will then be selected, and the timer will start. Several events will occur at different intervals during the duration of the timer. The events will be confined to changing the material of the selected object, and calling a 1 second sound effect like a chime or a bell. If the user wants to save or end the game before all the timers are done, the start of the still running timers is to be saved to an XML file such that when the game is started again, any still running timers will have a calculation done to see if the timer is then done, where the game will change the materials appropriately. I am still trying to figure out what type of timer to use, and see also if there are any suggestions for saving and calculating times over several days. What class(es) of timers should I use? Are there any special issues I should look out for in terms of performance?

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  • Fastest way to parse big json android

    - by jem88
    I've a doubt that doesn't let me sleep! :D I'm currently working with big json files, with many levels. I parse these object using the 'default' android way, so I read the response with a ByteArrayOutputStream, get a string and create a JSONObject from the string. All fine here. Now, I've to parse the content of the json to get the objects of my interest, and I really can't find a better way that parse it manually, like this: String status = jsonObject.getString("status"); Boolean isLogged = jsonObject.getBoolean("is_logged"); ArrayList<Genre> genresList = new ArrayList<Genre>(); // Get jsonObject with genres JSONObject jObjGenres = jsonObject.getJSONObject("genres"); // Instantiate an iterator on jsonObject keys Iterator<?> keys = jObjGenres.keys(); // Iterate on keys while( keys.hasNext() ) { String key = (String) keys.next(); JSONObject jObjGenre = jObjGenres.getJSONObject(key); // Create genre object Genre genre = new Genre( jObjGenre.getInt("id_genre"), jObjGenre.getString("string"), jObjGenre.getString("icon") ); genresList.add(genre); } // Get languages list JSONObject jObjLanguages = jsonObject.getJSONObject("languages"); Iterator jLangKey = jObjLanguages.keys(); List<Language> langList = new ArrayList<Language>(); while (jLangKey.hasNext()) { // Iterate on jlangKey obj String key = (String) jLangKey.next(); JSONObject jCurrentLang = (JSONObject) jObjLanguages.get(key); Language lang = new Language( jCurrentLang.getString("id_lang"), jCurrentLang.getString("name"), jCurrentLang.getString("code"), jCurrentLang.getString("active").equals("1") ); langList.add(lang); } I think this is really ugly, frustrating, timewaster, and fragile. I've seen parser like json-smart and Gson... but seems difficult to parse a json with many levels, and get the objects! But I guess that must be a better way... Any idea? Every suggestion will be really appreciated. Thanks in advance!

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  • Windows Azure Training Kit (November 2010 Release Update)&ndash;Fantastic Azure training resource

    - by Jim Duffy
    At PDC 2010 in October Microsoft announced a number of new enhancements/features for Windows Azure. In case you missed it, these new enhancements/features have been released in the new Windows Azure Tools for Visual Studio November release (v1.3). The Windows Azure team blog is an excellent resource for information about the new release. Along with the new release the Azure team has also updated the Windows Azure Platform Training Kit. What is the Windows Azure Platform Training Kit you ask? It is a comprehensive set of hands-on training labs and videos designed to help you quickly get up to speed with Windows Azure, SQL Azure, and the Windows Azure AppFabric. The training kit contains updated labs including a couple I would suggest you hit first. Introduction to Windows Azure - updated to use the new Windows Azure platform Portal Introduction to SQL Azure - updated to use the new Windows Azure platform Portal The training kit contains a number of new labs as well including: Advanced Web and Worker Role – shows how to use admin mode and startup tasks Connecting Apps With Windows Azure Connect – shows how to use Project Sydney Virtual Machine Role – shows how to get started with VM Role by creating and deploying a VHD Windows Azure CDN – simple introduction to the CDN Introduction to the Windows Azure AppFabric Service Bus Futures – shows how to use the new Service Bus features in the AppFabric labs environment Building Windows Azure Apps with Caching Service – shows how to use the new Windows Azure AppFabric Caching service Introduction to the AppFabric Access Control Service V2 – shows how to build a simple web application that supports multiple identity providers Ok, that’s enough reading, go start learning! Have a day.

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  • Problem with Ogre::Camera lookAt function when target is directly below.

    - by PigBen
    I am trying to make a class which controls a camera. It's pretty basic right now, it looks like this: class HoveringCameraController { public: void init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height); void update(Ogre::Real time_delta); private: Ogre::Camera * camera_; AnimatedBody * target_; Ogre::Real height_; }; HoveringCameraController.cpp void HoveringCameraController::init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height) { camera_ = &camera; target_ = &target; height_ = height; update(0.0); } void HoveringCameraController::update(Ogre::Real time_delta) { auto position = target_->getPosition(); position.y += height_; camera_->setPosition(position); camera_->lookAt(target_->getPosition()); } AnimatedBody is just a class that encapsulates an entity, it's animations and a scene node. The getPosition function is simply forwarded to it's scene node. What I want(for now) is for the camera to simply follow the AnimatedBody overhead at the distance given(the height parameter), and look down at it. It follows the object around, but it doesn't look straight down, it's tilted quite a bit in the positive Z direction. Does anybody have any idea why it would do that? If I change this line: position.y += height_; to this: position.x += height_; or this: position.z += height_; it does exactly what I would expect. It follows the object from the side or front, and looks directly at it.

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