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  • Algorithm for optimal control on space ship using accelerometer input data

    - by mm24
    Does someone have a good algorithm for controlling a space ship in a vertical shooter game using acceleration data? I have done a simple algorithm, but works very badly. I save an initial acceleration value (used to calibrate the movement according to the user's initial position) and I do subtract it from the current acceleration so I get a "calibrated" value. The problem is that basing the movement solely on relative acceleration has an effect of loss of sensitivity: certain movements are independent from the initial position. Would anyone be able to share a a better solution? I am wondering if I should use/integrate also inputs from gyroscope hardware. Here is my sample of code for a Cocos2d iOS game: - (void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { if (calibrationLayer.visible){ [self evaluateCalibration:acceleration]; initialAccelleration=acceleration; return; } if([self evaluatePause]){ return; } ShooterScene * shooterScene = (ShooterScene *) [self parent]; ShipEntity *playerSprite = [shooterScene playerShip]; float accellerationtSensitivity = 0.5f; UIAccelerationValue xAccelleration = acceleration.x - initialAccelleration.x; UIAccelerationValue yAccelleration = acceleration.y - initialAccelleration.y; if(xAccelleration > 0.05 || xAccelleration < -0.05) { [playerSprite setPosition:CGPointMake(playerSprite.position.x + xAccelleration * 80, playerSprite.position.y + yAccelleration * 80)]; } else if(yAccelleration > 0.05 || yAccelleration < -0.05) { [playerSprite setPosition:CGPointMake(playerSprite.position.x + xAccelleration * 80, playerSprite.position.y + yAccelleration * 80)]; } }

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  • Usage of repository between EF model and code consumer

    - by jim
    I have binary data in my database that I'll have to convert to bitmap at some point. I was thinking whether or not it's appropriate to use a repository and do it there. My consumer, which is a presentation layer, will use this repository. For example: // This is a class I created for modeling the item as is. public class RealItem { public string Name { get; set; } public Bitmap Image { get; set; } } public abstract class BaseRepository { //using Unity (http://unity.codeplex.com) to inject the dependancy of entity context. [Dependency] public Context { get; set; } } public calss ItemRepository : BaseRepository { public List<Items> Select() { IEnumerable<Items> items = from item in Context.Items select item; List<RealItem> lst = new List<RealItem>(); foreach(itm in items) { MemoryStream stream = new MemoryStream(itm.Image); Bitmap image = (Bitmap)Image.FromStream(stream); RealItem ritem = new RealItem{ Name=item.Name, Image=image }; lst.Add(ritem); } return lst; } } Is this a correct way to use the repository pattern? I'm learning this pattern and I've seen a lot of examples online that are using a repository but when I looked at their source code... for example: public IQueryable<object> Select { return from q in base.Context select q; } as you can see no behavior is added to the system by their approach, so I was confused that maybe repository is something else and I got it all wrong. At the end there should be extra benifits of using them right?

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  • Validating data to nest if or not within try and catch

    - by Skippy
    I am validating data, in this case I want one of three ints. I am asking this question, as it is the fundamental principle I'm interested in. This is a basic example, but I am developing best practices now, so when things become more complicated later, I am better equipped to manage them. Is it preferable to have the try and catch followed by the condition: public static int getProcType() { try { procType = getIntInput("Enter procedure type -\n" + " 1 for Exploratory,\n" + " 2 for Reconstructive, \n" + "3 for Follow up: \n"); } catch (NumberFormatException ex) { System.out.println("Error! Enter a valid option!"); getProcType(); } if (procType == 1 || procType == 2 || procType == 3) { hrlyRate = hrlyRate(procType); procedure = procedure(procType); } else { System.out.println("Error! Enter a valid option!"); getProcType(); } return procType; } Or is it better to put the if within the try and catch? public static int getProcType() { try { procType = getIntInput("Enter procedure type -\n" + " 1 for Exploratory,\n" + " 2 for Reconstructive, \n" + "3 for Follow up: \n"); if (procType == 1 || procType == 2 || procType == 3) { hrlyRate = hrlyRate(procType); procedure = procedure(procType); } else { System.out.println("Error! Enter a valid option!"); getProcType(); } } catch (NumberFormatException ex) { System.out.println("Error! Enter a valid option!"); getProcType(); } return procType; } I am thinking the if within the try, may be quicker, but also may be clumsy. Which would be better, as my programming becomes more advanced?

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  • MiniMax not working properly(for checkers game)

    - by engineer
    I am creating a checkers game but My miniMax is not functioning properly,it is always switching between two positions for its move(index 20 and 17).Here is my code: public double MiniMax(int[] board, int depth, int turn, int red_best, int black_best) { int source; int dest; double MAX_SCORE=-INFINITY,newScore; int MAX_DEPTH=3; int[] newBoard=new int[32]; generateMoves(board,turn); System.arraycopy(board, 0, newBoard, 0, 32); if(depth==MAX_DEPTH) { return Evaluation(turn,board);} for(int z=0;z<possibleMoves.size();z+=2){ source=Integer.parseInt(possibleMoves.elementAt(z).toString()); System.out.println("SOURCE= "+source); dest=Integer.parseInt(possibleMoves.elementAt(z+1).toString());//(int[])possibleMoves.elementAt(z+1); System.out.println("DEST = "+dest); applyMove(newBoard,source,dest); newScore=MiniMax(newBoard,depth+1,opponent(turn),red_best, black_best); if(newScore>MAX_SCORE) {MAX_SCORE=newScore;maxSource=source; maxDest=dest;}//maxSource and maxDest will be used to perform the move. if (MAX_SCORE > black_best) { if (MAX_SCORE >= red_best) break; /* alpha_beta cutoff */ else black_best = (int) MAX_SCORE; //the_score } if (MAX_SCORE < red_best) { if (MAX_SCORE<= black_best) break; /* alpha_beta cutoff */ else red_best = (int) MAX_SCORE; //the_score } }//for ends return MAX_SCORE; } //end minimax I am unable to find out the logical mistake. Any idea what's going wrong?

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  • Writing to a D3DFMT_R32F render target clamps to 1

    - by Mike
    I'm currently implementing a picking system. I render some objects in a frame buffer, which has a render target, which has the D3DFMT_R32F format. For each mesh, I set an integer constant evaluator, which is its material index. My shader is simple: I output the position of each vertex, and for each pixel, I cast the material index in float, and assign this value to the Red channel: int ObjectIndex; float4x4 WvpXf : WorldViewProjection< string UIWidget = "None"; >; struct VS_INPUT { float3 Position : POSITION; }; struct VS_OUTPUT { float4 Position : POSITION; }; struct PS_OUTPUT { float4 Color : COLOR0; }; VS_OUTPUT VSMain( const VS_INPUT input ) { VS_OUTPUT output = (VS_OUTPUT)0; output.Position = mul( float4(input.Position, 1), WvpXf ); return output; } PS_OUTPUT PSMain( const VS_OUTPUT input, in float2 vpos : VPOS ) { PS_OUTPUT output = (PS_OUTPUT)0; output.Color.r = float( ObjectIndex ); output.Color.gba = 0.0f; return output; } technique Default { pass P0 { VertexShader = compile vs_3_0 VSMain(); PixelShader = compile ps_3_0 PSMain(); } } The problem I have, is that somehow, the values written in the render target are clamped between 0.0f and 1.0f. I've tried to change the rendertarget format, but I always get clamped values... I don't know what the root of the problem is. For information, I have a depth render target attached to the frame buffer. I disabled the blend in the render state the stencil is disabled Any ideas?

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  • How AlphaBlend Blendstate works in XNA 4 when accumulighting light into a RenderTarget?

    - by cubrman
    I am using a Deferred Rendering engine from Catalin Zima's tutorial: His lighting shader returns the color of the light in the rgb channels and the specular component in the alpha channel. Here is how light gets accumulated: Game.GraphicsDevice.SetRenderTarget(LightRT); Game.GraphicsDevice.Clear(Color.Transparent); Game.GraphicsDevice.BlendState = BlendState.AlphaBlend; // Continuously draw 3d spheres with lighting pixel shader. ... Game.GraphicsDevice.BlendState = BlendState.Opaque; MSDN states that AlphaBlend field of the BlendState class uses the next formula for alphablending: (source × Blend.SourceAlpha) + (destination × Blend.InvSourceAlpha), where "source" is the color of the pixel returned by the shader and "destination" is the color of the pixel in the rendertarget. My question is why do my colors are accumulated correctly in the Light rendertarget even when the new pixels' alphas equal zero? As a quick sanity check I ran the following code in the light's pixel shader: float specularLight = 0; float4 light4 = attenuation * lightIntensity * float4(diffuseLight.rgb,specularLight); if (light4.a == 0) light4 = 0; return light4; This prevents lighting from getting accumulated and, subsequently, drawn on the screen. But when I do the following: float specularLight = 0; float4 light4 = attenuation * lightIntensity * float4(diffuseLight.rgb,specularLight); return light4; The light is accumulated and drawn exactly where it needs to be. What am I missing? According to the formula above: (source x 0) + (destination x 1) should equal destination, so the "LightRT" rendertarget must not change when I draw light spheres into it! It feels like the GPU is using the Additive blend instead: (source × Blend.One) + (destination × Blend.One)

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  • International search: how to show different domains in Google+ Local?

    - by Baumr
    Background A site has multiple ccTLDs: example.com for people in the US, example.co.uk for UK users, example.de for Germany, example.fr for France, etc. Searching for certain city keywords will return a list of Google+ Local (formerly Places): Each links to the corresponding company website that is visible. Problem When searching on www.google.de, the domain of the site intended for US users (example.com) appears instead of the corresponding ccTLD (example.de) aimed at German users. This applies to all languages. In my opinion and for the purposes of this business, it's not good user experience: searchers would most likely prefer to book on a site localized for them (e.g. in their language and currency). Question Is it possible to return different ccTLDs in these local search listings for users across the globe? Currently, Google+ Local seems to only support supports adding a single "Website" field. Solutions I have considered Creating duplicate Google Places listings for each URL would be spammy (and not viable when there's 100s of locations, each needing a listing in 8 languages). I don't see the hreflang annotation helping either, and GWMT geotargeting is already set.

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  • Reading OpenDocument spreadsheets using C#

    - by DigiMortal
    Excel with its file formats is not the only spreadsheet application that is widely used. There are also users on Linux and Macs and often they are using OpenOffice and other open-source office packages that use ODF instead of OpenXML. In this post I will show you how to read Open Document spreadsheet in C#. Importer as example My previous post about importers showed you how to build flexible importers support to your web application. This post introduces you practical example of one of my importers. Of course, sensitive code is omitted. We start with ODS importer class and we add new methods as we go. public class OdsImporter : ImporterBase {     public OdsImporter()     {     }       public override string[] SupportedFileExtensions     {         get { return new[] { "ods" }; }     }       public override ImportResult Import(Stream fileStream, long companyId, short year)     {         string contentXml = GetContentXml(fileStream);           var result = new ImportResult();         var doc = XDocument.Parse(contentXml);           var rows = doc.Descendants("{urn:oasis:names:tc:opendocument:xmlns:table:1.0}table-row").Skip(1);           foreach (var row in rows)         {             ImportRow(row, companyId, year, result);         }           return result;     } } The class given here just extends base class for importers (previous post uses interface but as I already told there you move to abstract base class when writing code for real projects). Import method reads data from *.ods file, parses it (it is XML), finds all data rows and imports data. As you may see then first row is skipped. This is because the first row on my sheet is always headers row. Reading ODS file Our import method starts with getting XML from *.ods file. ODS files like OpenXml files are zipped containers that contain different files. We need content.xml as all data is kept there. To get the contents of file we use SharpZipLib library to read uploaded file as *.zip file. private static string GetContentXml(Stream fileStream) {     var contentXml = "";       using (var zipInputStream = new ZipInputStream(fileStream))     {         ZipEntry contentEntry = null;         while ((contentEntry = zipInputStream.GetNextEntry()) != null)         {             if (!contentEntry.IsFile)                 continue;             if (contentEntry.Name.ToLower() == "content.xml")                 break;         }           if (contentEntry.Name.ToLower() != "content.xml")         {             throw new Exception("Cannot find content.xml");         }           var bytesResult = new byte[] { };         var bytes = new byte[2000];         var i = 0;           while ((i = zipInputStream.Read(bytes, 0, bytes.Length)) != 0)         {             var arrayLength = bytesResult.Length;             Array.Resize<byte>(ref bytesResult, arrayLength + i);             Array.Copy(bytes, 0, bytesResult, arrayLength, i);         }         contentXml = Encoding.UTF8.GetString(bytesResult);     }     return contentXml; } If here is content.xml file then we stop browsing the file. We read this file to memory and return it as UTF-8 format string. Importing rows Our last task is to import rows. We use special method for this as we have to handle some tricks here. To keep files smaller the cell count on row is not always the same. If we have more than one empty cell one after another then ODS keeps only one cell for sequential empty cells. This cell has attribute called number-columns-repeated and it’s value is set to the number of sequential empty cells. This is why we use two indexers for cells collection. private void ImportRow(XElement row, ImportResult result) {     var cells = (from c in row.Descendants()                 where c.Name == "{urn:oasis:names:tc:opendocument:xmlns:table:1.0}table-cell"                 select c).ToList();       var dto = new DataDto();       var count = cells.Count;     var j = -1;       for (var i = 0; i < count; i++)     {         j++;         var cell = cells[i];         var attr = cell.Attribute("{urn:oasis:names:tc:opendocument:xmlns:table:1.0}number-columns-repeated");         if (attr != null)         {             var numToSkip = 0;             if (int.TryParse(attr.Value, out numToSkip))             {                 j += numToSkip - 1;             }         }           if (i > 30) break;         if (j == 0)         {             dto.SomeProperty = cells[i].Value;         }         if (j == 1)         {             dto.SomeOtherProperty = cells[i].Value;         }         // some more data reading     }       // save data } You can define your own class for import results and add there all problems found during data import. Your application gets the results and shows them to user. Conclusion Reading ODS files may seem to complex task but actually it is very easy if we need only data from those documents. We can use some zip-library to get the content file and then parse it to XML. It is not hard to go through the XML but there are some optimization tricks we have to know. The code here is safe to use in web applications as it is not using any API-s that may have special needs to server and infrastructure.

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  • What is the difference between Callback<T> and Java 8's Supplier<T>?

    - by Dan Pantry
    I've been switching over to Java from C# after some recommendations from some over at CodeReview. So, when I was looking into LWJGL, one thing I remembered was that every call to Display must be executed on the same thread that the Display.create() method was invoked on. Remembering this, I whipped up a class that looks a bit like this. public class LwjglDisplayWindow implements DisplayWindow { private final static int TargetFramesPerSecond = 60; private final Scheduler _scheduler; public LwjglDisplayWindow(Scheduler displayScheduler, DisplayMode displayMode) throws LWJGLException { _scheduler = displayScheduler; Display.setDisplayMode(displayMode); Display.create(); } public void dispose() { Display.destroy(); } @Override public int getTargetFramesPerSecond() { return TargetFramesPerSecond; } @Override public Future<Boolean> isClosed() { return _scheduler.schedule(() -> Display.isCloseRequested()); } } While writing this class you'll notice that I created a method called isClosed() that returns a Future<Boolean>. This dispatches a function to my Scheduler interface (which is nothing more than a wrapper around an ScheduledExecutorService. While writing the schedule method on the Scheduler I noticed that I could either use a Supplier<T> argument or a Callable<T> argument to represent the function that is passed in. ScheduledExecutorService didn't contain an override for Supplier<T> but I noticed that the lambda expression () -> Display.isCloseRequested() is actually type compatible with both Callable<bool> and Supplier<bool>. My question is, is there a difference between those two, semantically or otherwise - and if so, what is it, so I can adhere to it?

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  • call function between classes [closed]

    - by aziz joh
    hello I have 3 classes class A, B, and C class A is the main class and content the main function also, i call class B and class C in the main as b1,b2 and c1. in class B there is a vector (V) has list of int. and 3 functions Add, get and delete delete. all the thing in the class is public. in class C i have function that need to (B::get) from b. what I want is that how I can make c1 call get of b1 to return the value of the V in b1 after that use add of b2 to add new item in V of b2. Thanks in advance This is an example class a{ int main(){ b b1,b2; c c1; b1.add(10); b1.add(20); c1.start(); }} class b{ vector<int> v; void add(int i){ v.push_back(i)} int get(){int i=v.at(0); return i;} } class c{// take something from b1 and add it to b2 void play(){ int i=b.get();//should take it from b1 b.add(i*2);//should add it to b2 }} please I need your help I been searching to solve this problem for days.

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  • Making a perfect map (not tile-based)

    - by Sri Harsha Chilakapati
    I would like to make a map system as in the GameMaker and the latest code is here. I've searched a lot in google and all of them resulted in tutorials about tile-maps. As tile maps do not fit for every type of game and GameMaker uses tiles for a different purpose, I want to make a "Sprite Based" map. The major problem I had experienced was collision detection being slow for large maps. So I wrote a QuadTree class here and the collision detection is fine upto 50000 objects in the map without PixelPerfect collision detection and 30000 objects with PixelPerferct collisions enabled. Now I need to implement the method "isObjectCollisionFree(float x, float y, boolean solid, GObject obj)". The existing implementation is becoming slow in Platformer games and I need suggestions on improvement. The current Implementation: /** * Checks if a specific position is collision free in the map. * * @param x The x-position of the object * @param y The y-position of the object * @param solid Whether to check only for solid object * @param object The object ( used for width and height ) * @return True if no-collision and false if it collides. */ public static boolean isObjectCollisionFree(float x, float y, boolean solid, GObject object){ boolean bool = true; Rectangle bounds = new Rectangle(Math.round(x), Math.round(y), object.getWidth(), object.getHeight()); ArrayList<GObject> collidables = quad.retrieve(bounds); for (int i=0; i<collidables.size(); i++){ GObject obj = collidables.get(i); if (obj.isSolid()==solid && obj != object){ if (obj.isAlive()){ if (bounds.intersects(obj.getBounds())){ bool = false; if (Global.USE_PIXELPERFECT_COLLISION){ bool = !GUtil.isPixelPerfectCollision(x, y, object.getAnimation().getBufferedImage(), obj.getX(), obj.getY(), obj.getAnimation().getBufferedImage()); } break; } } } } return bool; } Thanks.

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  • Differences when Running with OutputCache managed module under ASP.NET IIS7.x with Cache-control header

    - by Shawn Cicoria
    This post is to report some differences when using MVC or IHttpHandlers if you’re attempting to set the Cache-control : max-age or s-maxage value under IIS7.x using the HttpResponse.Cache methods. [UPDATE]: 2011-3-14 – The missing piece was calling  Response.Cache.SetSlidingExpiration(true) as follows: context.Response.Cache.SetCacheability(HttpCacheability.Public); context.Response.Cache.SetMaxAge(TimeSpan.FromMinutes(5)); context.Response.ContentType = "image/jpeg"; context.Response.Cache.SetSlidingExpiration(true);   Under IIS7.x if you us one of the following 2 methods, you will only get a Cache-ability of “public”.  public ActionResult Image2() { MemoryStream oStream = new MemoryStream(); using (Bitmap obmp = ImageUtil.RenderImage("Respone.Cache.Setxx calls", 5, DateTime.Now)) { obmp.Save(oStream, ImageFormat.Jpeg); oStream.Position = 0; Response.Cache.SetCacheability(HttpCacheability.Public); Response.Cache.SetMaxAge(TimeSpan.FromMinutes(5)); return new FileStreamResult(oStream, "image/jpeg"); } } Method 2 – which is just a plain old HttpHandler and really isn’t MVC3, but under the same MVC ASP.NET application, same result. public class image : IHttpHandler { public void ProcessRequest(HttpContext context) { using (var image = ImageUtil.RenderImage("called from IHttpHandler direct", 5, DateTime.Now)) { context.Response.Cache.SetCacheability(HttpCacheability.Public); context.Response.Cache.SetMaxAge(TimeSpan.FromMinutes(5)); context.Response.ContentType = "image/jpeg"; image.Save(context.Response.OutputStream, ImageFormat.Jpeg); } } } Using the following under MVC3 (I haven’t tried under earlier versions) will work by applying the OutputCacheAttribute to your Action: [OutputCache(Location = OutputCacheLocation.Any, Duration = 300)] public ActionResult Image1() { MemoryStream oStream = new MemoryStream(); using (Bitmap obmp = ImageUtil.RenderImage("called with OutputCacheAttribute", 5, DateTime.Now)) { obmp.Save(oStream, ImageFormat.Jpeg); oStream.Position = 0; return new FileStreamResult(oStream, "image/jpeg"); } } To remove the “OutputCache” module, you use the following in your web.config: <system.webServer> <validation validateIntegratedModeConfiguration="false"/> <modules runAllManagedModulesForAllRequests="true"> <!--<remove name="OutputCache"/>--> </modules>

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  • How to automatically render all opaque meshes with a specific shader?

    - by dsilva.vinicius
    I have a specular outline shader that I want to be used on all opaque meshes of the scene whenever a specific camera renders. The shader is working properly when it is manually applied to some material. The shader is as follows: Shader "Custom/Outline" { Properties { _Color ("Main Color", Color) = (.5,.5,.5,1) _OutlineColor ("Outline Color", Color) = (1,0.5,0,1) _Outline ("Outline width", Range (0.0, 0.1)) = .05 _SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 1) _Shininess ("Shininess", Range (0.03, 1)) = 0.078125 _MainTex ("Base (RGB) Gloss (A)", 2D) = "white" {} } SubShader { Tags { "Queue"="Overlay" "RenderType"="Opaque" } Pass { Name "OUTLINE" Tags { "LightMode" = "Always" } Cull Off ZWrite Off // Uncomment to show outline always. //ZTest Always CGPROGRAM #pragma target 3.0 #pragma vertex vert #pragma fragment frag #include "UnityCG.cginc" struct appdata { float4 vertex : POSITION; float3 normal : NORMAL; }; struct v2f { float4 pos : POSITION; float4 color : COLOR; }; float _Outline; float4 _OutlineColor; v2f vert(appdata v) { // just make a copy of incoming vertex data but scaled according to normal direction v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex); float3 norm = mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal); float2 offset = TransformViewToProjection(norm.xy); o.pos.xy += offset * o.pos.z * _Outline; o.color = _OutlineColor; return o; } float4 frag(v2f fromVert) : COLOR { return fromVert.color; } ENDCG } UsePass "Specular/FORWARD" } FallBack "Specular" } The camera used fot the effect has just a script component which setups the shader replacement: using UnityEngine; using System.Collections; public class DetectiveEffect : MonoBehaviour { public Shader EffectShader; // Use this for initialization void Start () { this.camera.SetReplacementShader(EffectShader, "RenderType=Opaque"); } // Update is called once per frame void Update () { } } Unfortunately, whenever I use this camera I just see the background color. Any ideas?

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  • SFML - Moving a sprite on mouseclick

    - by Mike
    I want to be able to move a sprite from a current location to another based upon where the user clicks in the window. This is the code that I have: #include <SFML/Graphics.hpp> int main() { // Create the main window sf::RenderWindow App(sf::VideoMode(800, 600), "SFML window"); // Load a sprite to display sf::Texture Image; if (!Image.LoadFromFile("cb.bmp")) return EXIT_FAILURE; sf::Sprite Sprite(Image); // Define the spead of the sprite float spriteSpeed = 200.f; // Start the game loop while (App.IsOpened()) { if (sf::Keyboard::IsKeyPressed(sf::Keyboard::Escape)) App.Close(); if (sf::Mouse::IsButtonPressed(sf::Mouse::Right)) { Sprite.SetPosition(sf::Mouse::GetPosition(App).x, sf::Mouse::GetPosition(App).y); } // Clear screen App.Clear(); // Draw the sprite App.Draw(Sprite); // Update the window App.Display(); } return EXIT_SUCCESS; } But instead of just setting the position I want to use Sprite.Move() and gradually move the sprite from one position to another. The question is how? Later I plan on adding a node system into each map so I can use Dijkstra's algorithm, but I'll still need this for moving between nodes.

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  • What are the hard and fast rules for Cache Control?

    - by Metalshark
    Confession: sites I maintain have different rules for Cache Control mostly based on the default configuration of the server followed up with recommendations from the Page Speed & Y-Slow Firefox plug-ins and the Network Resources view in Google's Speed Tracer. Cache-Control is set to private/public depending on what they say to do, ETag's/Last-Modified headers are only tinkered with if Y-Slow suggests there is something wrong and Vary-Accept-Encoding seems necessary when manually gziping files for Amazon CloudFront. When reading through the material on the different options and what they do there seems to be conflicting information, rules for broken proxies and cargo cult configurations. Any of the official information provided by the analysis tools mentioned above is quite inaccessible as it deals with each topic individually instead of as a unified strategy (so there is no cross-referencing of techniques). For example, it seems to make no sense that the speed analysis tools rate a site with ETag's the same as a site without them if they are meant to help with caching. What are the hard and fast rules for a platform agnostic Cache Control strategy? EDIT: A link through Jeff Atwood's article explains Caching in superb depth. For the record though here are the hard and fast rules: If the file is Compressed using GZIP, etc - use "cache-control: private" as a proxy may return the compressed version to a client that does not support it (the browser cache will hold files marked this way though). Also remember to include a "Vary: Accept-Encoding" to say that it is compressible. Use Last-Modified in conjunction with ETag - belt and braces usage provides both validators, whilst ETag is based on file contents instead of modification time alone, using both covers all bases. NOTE: AOL's PageTest has a carte blanche approach against ETags for some reason. If you are using Apache on more than one server to host the same content then remove the implicitly declared inode from ETags by excluding it from the FileETag directive (i.e. "FileETag MTime Size") unless you are genuinely using the same live filesystem. Use "cache-control: public" wherever you can - this means that proxy servers (and the browser cache) will return your content even if the rest of the page needs HTTP authentication, etc.

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  • Understanding math used to determine if vector is clockwise / counterclockwise from your vector

    - by MTLPhil
    I'm reading Programming Game AI by Example by Mat Buckland. In the Math & Physics primer chapter there's a listing of the declaration of a class used to represent 2D vectors. This class contains a method called Sign. It's implementation is as follows //------------------------ Sign ------------------------------------------ // // returns positive if v2 is clockwise of this vector, // minus if anticlockwise (Y axis pointing down, X axis to right) //------------------------------------------------------------------------ enum {clockwise = 1, anticlockwise = -1}; inline int Vector2D::Sign(const Vector2D& v2)const { if (y*v2.x > x*v2.y) { return anticlockwise; } else { return clockwise; } } Can someone explain the vector rules that make this hold true? What do the values of y*v2.x and x*v2.y that are being compared actually represent? I'd like to have a solid understanding of why this works rather than just accepting that it does without figuring it out. I feel like it's something really obvious that I'm just not catching on to. Thanks for your help.

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  • Why the R# Method Group Refactoring is Evil

    - by Liam McLennan
    The refactoring I’m talking about is recommended by resharper when it sees a lambda that consists entirely of a method call that is passed the object that is the parameter to the lambda. Here is an example: public class IWishIWasAScriptingLanguage { public void SoIWouldntNeedAllThisJunk() { (new List<int> {1, 2, 3, 4}).Select(n => IsEven(n)); } private bool IsEven(int number) { return number%2 == 0; } } When resharper gets to n => IsEven(n) it underlines the lambda with a green squiggly telling me that the code can be replaced with a method group. If I apply the refactoring the code becomes: public class IWishIWasAScriptingLanguage { public void SoIWouldntNeedAllThisJunk() { (new List<int> {1, 2, 3, 4}).Select(IsEven); } private bool IsEven(int number) { return number%2 == 0; } } The method group syntax implies that the lambda’s parameter is the same as the IsEven method’s parameter. So a readable, explicit syntax has been replaced with an obfuscated, implicit syntax. That is why the method group refactoring is evil.

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  • Choosing Technology To Include In Software Design

    How many of us have been forced to select one technology over another when designing a new system? What factors do we and should we consider? How can we ensure the correct business decision is made? When faced with this type of decision it is important to gather as much information possible regarding each technology being considered as well as the project itself. Additionally, I tend to delay my decision about the technology until it is ultimately necessary to be made. The reason why I tend to delay such an important design decision is due to the fact that as the project progresses requirements and other factors can alter a decision for selecting the best technology for a project. Important factors to consider when making technology decisions: Time to Implement and Maintain Total Cost of Technology (including Implementation and maintenance) Adaptability of Technology Implementation Team’s Skill Sets Complexity of Technology (including Implementation and maintenance) orecasted Return On Investment (ROI) Forecasted Profit on Investment (POI) Of the factors to consider the ROI and POI weigh the heaviest because the take in to consideration the other factors when calculating the profitability and return on investments.For a real world example let us consider developing a web based lead management system for a new company. This system can either be hosted on Microsoft Windows based web server or on a Linux based web server. Important Factors for this Example Implementation Team’s Skill Sets Member 1  Skill Set: Classic ASP, ASP.Net, and MS SQL Server Experience: 10 years Member 2  Skill Set: PHP, MySQL, Photoshop and MS SQL Server Experience: 3 years Member 3  Skill Set: C++, VB6, ASP.Net, and MS SQL Server Experience: 12 years Total Cost of Technology (including Implementation and maintenance) Linux Initial Year: $5,000 (Random Value) Additional Years: $3,000 (Random Value) Windows Initial Year: $10,000 (Random Value) Additional Years: $3,000 (Random Value) Complexity of Technology Linux Large Learning Curve with user driven documentation Estimated learning cost: $30,000 Windows Minimal based on Teams skills with Microsoft based documentation Estimated learning cost: $5,000 ROI Linux Total Cost Initial Total Cost: $35,000 Additional Cost $3,000 per year Windows Total Cost Initial Total Cost: $15,000 Additional Cost $3,000 per year Based on the hypothetical numbers it would make more sense to select windows based web server because the initial investment of the technology is much lower initially compared to the Linux based web server.

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  • Can't install or update Ubuntu after using parameter acpi_osi = Linux

    - by Lucas Leitão
    I recently had an issue with my acer 4736z notebook because I was having a blank screen after booting the OS, then someone told me to use the parameter GRUB_CMDLINE_LINUX_DEFAULT = "quiet splash acpi_osi = Linux" after quiet splash inside the grub. It worked for me, but since then I can't install a thing or update anything on Linux because it says Removing linux-image-extra-3.5.0-17-generic ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic update-initramfs: Deleting /boot/initrd.img-3.5.0-17-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic /usr/sbin/grub-mkconfig: 11: /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT: not found run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 127 Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-extra-3.5.0-17-generic.postrm line 328. dpkg: erro ao processar linux-image-extra-3.5.0-17-generic (--remove): sub-processo script post-removal instalado retornou estado de saída de erro 1 Removendo linux-image-3.5.0-17-generic ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic update-initramfs: Deleting /boot/initrd.img-3.5.0-17-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.5.0-17-generic /boot/vmlinuz-3.5.0-17-generic /usr/sbin/grub-mkconfig: 11: /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT: not found run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 127 Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-3.5.0-17-generic.postrm line 328. dpkg: erro ao processar linux-image-3.5.0-17-generic (--remove): sub-processo script post-removal instalado retornou estado de saída de erro 1 Erros foram encontrados durante o processamento de: linux-image-extra-3.5.0-17-generic linux-image-3.5.0-17-generic E: Sub-process /usr/bin/dpkg returned an error code (1) I already tried to remove older kernels but it gives me the same message. Do you have a clue about what should I do?

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  • Change a Foreign Action's Display Text

    - by Geertjan
    I want the display text on an Action on a Node to show something about the underlying object. But the Action is registered somewhere in the layer (i.e., in the registry), i.e., I have no control over it. How do I change the display text in this scenario? Here's how. Below I look in the Actions/Events folder, iterate through all the Actions registered there, look for an Action with display text starting with "Edit", change it to display something from the underlying object, wrap a new Action around that Action, build up a new list of Actions, and return those (together with all the other Actions in that folder) from "getActions" on my Node: @Override public Action[] getActions(boolean context) { List<Action> newEventActions = new ArrayList<Action>(); List<? extends Action> eventActions = Utilities.actionsForPath("Actions/Events"); for (final Action action : eventActions) { String value = action.getValue(Action.NAME).toString(); if (value.startsWith("Edit")) { Action editAction = new AbstractAction("Edit " + getLookup().lookup(Event.class).getPlace()) { @Override public void actionPerformed(ActionEvent e) { action.actionPerformed(e); } }; newEventActions.add(editAction); } else { newEventActions.add(action); } } return newEventActions.toArray(new Action[eventActions.size()]); } If someone knows of a better way, please let me know.

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  • Confused about javascript module pattern implementation

    - by Damon
    I have a class written on a project I'm working on that I've been told is using the module pattern, but it's doing things a little differently than the examples I've seen. It basically takes this form: (function ($, document, window, undefined) { var module = { foo : bar, aMethod : function (arg) { className.bMethod(arg); }, bMethod : function (arg) { console.log('spoons'); } }; window.ajaxTable = ajaxTable; })(jQuery, document, window); I get what's going on here. But I'm not sure how this relates to most of the definitions I've seen of the module (or revealing?) module pattern. like this one from briancray var module = (function () { // private variables and functions var foo = 'bar'; // constructor var module = function () { }; // prototype module.prototype = { constructor: module, something: function () { } }; // return module return module; })(); var my_module = new module(); Is the first example basically like the second except everything is in the constructor? I'm just wrapping my head around patterns and the little things at the beginnings and endings always make me not sure what I should be doing.

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  • Design for object with optional and modifiable attributtes?

    - by Ikuzen
    I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block and other authors, and haven't needed to change their values. I am wondering what should I do though if I need a class with a substantial number of optional but non-final (mutable) attributes? My Builder pattern code looks like this: public class Example { //All possible parameters (optional or not) private final int param1; private final int param2; //Builder class public static class Builder { private final int param1; //Required parameters private int param2 = 0; //Optional parameters - initialized to default //Builder constructor public Builder (int param1) { this.param1 = param1; } //Setter-like methods for optional parameters public Builder param2(int value) { param2 = value; return this; } //build() method public Example build() { return new Example(this); } } //Private constructor private Example(Builder builder) { param1 = builder.param1; param2 = builder.param2; } } Can I just remove the final keyword from the declaration to be able to access the attributes externally (through normal setters, for example)? Or is there a creational pattern that allows optional but non-final attributes that would be better suited in this case?

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  • Ways to organize interface and implementation in C++

    - by Felix Dombek
    I've seen that there are several different paradigms in C++ concerning what goes into the header file and what to the cpp file. AFAIK, most people, especially those from a C background, do: foo.h class foo { private: int mem; int bar(); public: foo(); foo(const foo&); foo& operator=(foo); ~foo(); } foo.cpp #include foo.h foo::bar() { return mem; } foo::foo() { mem = 42; } foo::foo(const foo& f) { mem = f.mem; } foo::operator=(foo f) { mem = f.mem; } foo::~foo() {} int main(int argc, char *argv[]) { foo f; } However, my lecturers usually teach C++ to beginners like this: foo.h class foo { private: int mem; int bar() { return mem; } public: foo() { mem = 42; } foo(const foo& f) { mem = f.mem; } foo& operator=(foo f) { mem = f.mem; } ~foo() {} } foo.cpp #include foo.h int main(int argc, char* argv[]) { foo f; } // other global helper functions, DLL exports, and whatnot Originally coming from Java, I have also always stuck to this second way for several reasons, such as that I only have to change something in one place if the interface or method names change, that I like the different indentation of things in classes when I look at their implementation, and that I find names more readable as foo compared to foo::foo. I want to collect pro's and con's for either way. Maybe there are even still other ways? One disadvantage of my way is of course the need for occasional forward declarations.

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  • Variables in static library are never initialized. Why?

    - by Coyote
    I have a bunch of variables that should be initialized then my game launches, but must of them are never initialized. Here is an example of the code: MyClass.h class MyClass : public BaseObject { DECLARE_CLASS_RTTI(MyClass, BaseObject); ... }; MyClass.cpp REGISTER_CLASS(MyClass) Where REGISTER_CLASS is a macro defined as follow #define REGISTER_CLASS(className)\ class __registryItem##className : public __registryItemBase {\ virtual className* Alloc(){ return NEW className(); }\ virtual BaseObject::RTTI& GetRTTI(){ return className::RTTI; }\ }\ \ const __registryItem##className __registeredItem##className(#className); and __registryItemBase looks like this: class __registryItemBase { __registryItemBase(const _string name):mName(name){ ClassRegistry::Register(this); } const _string mName; virtual BaseObject* Alloc() = 0; virtual BaseObject::RTTI& GetRTTI() = 0; } Now the code is similar to what I currently have and what I have works flawlessly, all the registered classes are registered to a ClassManager before main(...) is called. I'm able to instantiate and configure components from scripts and auto-register them to the right system etc... The problem arrises when I create a static library (currently for the iPhone, but I fear it will happen with android as well). In that case the code in the .cpp files is never registered. Why is the resulting code not executed when it is in the library while the same code in the program's binary is always executed? Bonus questions: For this to work in the static library, what should I do? Is there something I am missing? Do I need to pass a flag when building the lib? Should I create another structure and init all the __registeredItem##className using that structure?

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  • Is there a better way to consume an ASP.NET Web API call in an MVC controller?

    - by davidisawesome
    In a new project I am creating for my work I am creating a fairly large ASP.NET Web API. The api will be in a separate visual studio solution that also contains all of my business logic and database interactions, Model classes as well. In the test application I am creating (which is asp.net mvc4), I want to be able to hit an api url I defined from the control and cast the return JSON to a Model class. The reason behind this is that I want to take advantage of strongly typing my views to a Model. This is all still in a proof of concept stage, so I have not done any performance testing on it, but I am curious if what I am doing is a good practice, or if I am crazy for even going down this route. Here is the code on the client controller: public class HomeController : Controller { protected string dashboardUrlBase = "http://localhost/webapi/api/StudentDashboard/"; public ActionResult Index() //This view is strongly typed against User { //testing against Joe Bob string adSAMName = "jBob"; WebClient client = new WebClient(); string url = dashboardUrlBase + "GetUserRecord?userName=" + adSAMName; //'User' is a Model class that I have defined. User result = JsonConvert.DeserializeObject<User>(client.DownloadString(url)); return View(result); } . . . } If I choose to go this route another thing to note is I am loading several partial views in this page (as I will also do in subsequent pages). The partial views are loaded via an $.ajax call that hits this controller and does basically the same thing as the code above: Instantiate a new WebClient Define the Url to hit Deserialize the result and cast it to a Model Class. So it is possible (and likely) I could be performing the same actions 4-5 times for a single page. Is there a better method to do this that will: Let me keep strongly typed views. Do my work on the server rather than on the client (this is just a preference since I can write C# faster than I can write javascript).

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