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  • SQL placeholder in WHERE IN issue, inserted strings fail.

    - by Alastair Pitts
    As part of my jobs, I need to writes SQL queries to connect to our PI database. To generate a query, I need to pass an array of tags (essentially primary keys), but these have to be inserted as strings. As this will be a modular query and used for multiple tags, a placeholder is being used. The query relies upon the use of the WHERE IN statement, which is where the placeholder is, like below: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN (?) AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' The issue is the format in which the tags are to be passed in as. If I add them directly into the query (for testing), they go in the format (these are example numbers): '000000012','00000032','005050236','4560236' and the query looks like: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN ('000000012','00000032','005050236','4560236') AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' which works. If I try and add the same tags into the placeholder, the query fails. If I only add 1 tag, with no quotes (using the placeholder), the query works. Why is this happening? Is there anyway around it?

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  • Game Physics With RK4 Implementation For A 2D Platformer

    - by oscar.rpr
    I been reading about RK4 for physics implementation in a game, so I read in some pages and all people recommend me this page: http://gafferongames.com/game-physics/fix-your-timestep/ This page shows clearly how this one works, but I can't figure out how to implement in my game, maybe I don't understand that good but I find some things that are not really clearly to me. In my game, the player decides when change direction in the X-Axis but I can't figure out how with this RK4 implementation change the direction of the object, in the example the point goes side to side but I don't understand how I can control when he goes right or left. So if anyone can give a little bit of clarity in this implementation and my problem which I do not understand I will be really grateful. Thanks beforehand

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  • Frameskipping in Android gameloop causing choppy sprites (Open GL ES 2.0)

    - by user22241
    I have written a simple 2d platform game for Android and am wondering how one deals with frame-skipping? Are there any alternatives? Let me explain further. So, my game loop allows for the rendering to be skipped if game updates and rendering do not fit into my fixed time-slice (16.667ms). This allows my game to run at identically perceived speeds on different devices. And this works great, things do run at the same speed. However, when the gameloop skips a render call for even one frame, the sprite glitches. And thinking about it, why wouldn't it? You're seeing a sprite move say, an average of 10 pixels every 1.6 seconds, then suddenly, there is a pause of 3.2ms, and the sprite then appears to jump 20 pixels. When this happens 3 or 4 times in close succession, the result is very ugly and not something I want in my game. Therfore, my question is how does one deal with these 'pauses' and 'jumps' - I've read every article on game loops I can find (see below) and my loops are even based off of code from these articles. The articles specifically mention frame skipping but they don't make any reference to how to deal with visual glitches that result from it. I've attempted various game-loops. My loop must have a mechanism in-place to allow rendering to be skipped to keep game-speed constant across multiple devices (or alternative, if one exists) I've tried interpolation but this doesn't eliminate this specific problem (although it looks like it may mitigate the issue slightly as when it eventually draws the sprite it 'moves it back' between the old and current positions so the 'jump' isn't so big. I've also tried a form of extrapolation which does seem to keep things smooth considerably, but I find it to be next to completely useless because it plays havoc with my collision detection (even when drawing with a 'display only' coordinate - see extrapolation-breaks-collision-detection) I've tried a loop that uses Thread.sleep when drawing / updating completes with time left over, no frame skipping in this one, again fairly smooth, but runs differently on different devices so no good. And I've tried spawning my own, third thread for logic updates, but this, was extremely messy to deal with and the performance really wasn't good. (upon reading tons of forums, most people seem to agree a 2 thread loops ( so UI and GL threads) is safer / easier). Now if I remove frame skipping, then all seems to run nice and smooth, with or without inter/extrapolation. However, this isn't an option because the game then runs at different speeds on different devices as it falls behind from not being able to render fast enough. I'm running logic at 60 Ticks per second and rendering as fast as I can. I've read, as far as I can see every article out there, I've tried the loops from My Secret Garden and Fix your timestep. I've also read: Against the grain deWITTERS Game Loop Plus various other articles on Game-loops. A lot of the others are derived from the above articles or just copied word for word. These are all great, but they don't touch on the issues I'm experiencing. I really have tried everything I can think of over the course of a year to eliminate these glitches to no avail, so any and all help would be appreciated. A couple of examples of my game loops (Code follows): From My Secret Room public void onDrawFrame(GL10 gl) { //Rre-set loop back to 0 to start counting again loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip) { SceneManager.getInstance().getCurrentScene().updateLogic(); nextGameTick += skipTicks; timeCorrection += (1000d / ticksPerSecond) % 1; nextGameTick += timeCorrection; timeCorrection %= 1; loops++; } extrapolation = (float)(System.currentTimeMillis() + skipTicks - nextGameTick) / (float)skipTicks; render(extrapolation); } And from Fix your timestep double t = 0.0; double dt2 = 0.01; double currentTime = System.currentTimeMillis()*0.001; double accumulator = 0.0; double newTime; double frameTime; @Override public void onDrawFrame(GL10 gl) { newTime = System.currentTimeMillis()*0.001; frameTime = newTime - currentTime; if ( frameTime > (dt*5)) //Allow 5 'skips' frameTime = (dt*5); currentTime = newTime; accumulator += frameTime; while ( accumulator >= dt ) { SceneManager.getInstance().getCurrentScene().updateLogic(); previousState = currentState; accumulator -= dt; } interpolation = (float) (accumulator / dt); render(interpolation); }

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  • Box2Dweb very slow on node.js

    - by Peteris
    I'm using Box2Dweb on node.js. I have a rotated box object that I apply an impulse to move around. The timestep is set at 50ms, however, it bumps up to 100ms and even 200ms as soon as I add any more edges or boxes. Here are the edges I would like to use as bounds around the playing area: // Computing the corners var upLeft = new b2Vec2(0, 0), lowLeft = new b2Vec2(0, height), lowRight = new b2Vec2(width, height), upRight = new b2Vec2(width, 0) // Edges bounding the visible game area var edgeFixDef = new b2FixtureDef edgeFixDef.friction = 0.5 edgeFixDef.restitution = 0.2 edgeFixDef.shape = new b2PolygonShape var edgeBodyDef = new b2BodyDef; edgeBodyDef.type = b2Body.b2_staticBody edgeFixDef.shape.SetAsEdge(upLeft, lowLeft) world.CreateBody(edgeBodyDef).CreateFixture(edgeFixDef) edgeFixDef.shape.SetAsEdge(lowLeft, lowRight) world.CreateBody(edgeBodyDef).CreateFixture(edgeFixDef) edgeFixDef.shape.SetAsEdge(lowRight, upRight) world.CreateBody(edgeBodyDef).CreateFixture(edgeFixDef) edgeFixDef.shape.SetAsEdge(upRight, upLeft) world.CreateBody(edgeBodyDef).CreateFixture(edgeFixDef) Can box2d really become this slow for even two bodies or is there some pitfall? It would be very surprising given all the demos which successfully use tens of objects.

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  • Box2D blocky map. Body, Fixtures a huge map and performance

    - by Solom
    Right now I'm still in the planning phase of a my very first game. I'm creating a "Minecraft"-like game in 2D that features blocks that can be destroyed as well as players moving around the map. For creating the map I chose a 2D-Array of Integers that represent the Block ID. For testing purposes I created a huge map (16348 * 256) and in my prototype that didn't use Box2D everything worked like a charm. I only rendered those blocks that where within the bounds of my camera and got 60 fps straight. The problem started when I decided to use an existing physics-solution rather than implementing my own one. What I had was basically simple hitboxes around the blocks and then I had to manually check if the player collided with any of those in his neighborhood. For more advanced physics as well as the collision detection I want to switch over to Box2D. The problem I have right now is ... how to go about the bodies? I mean, the blocks are of a static bodytype. They don't move on their own, they just are there to be collided with. But as far as I can see it, every block needs his own body with a rectangular fixture attached to it, so as to be destroyable. But for a huge map such as mine, this turns out to be a real performance bottle-neck. (In fact even a rather small map [compared to the other] of 1024*256 is unplayable.) I mean I create thousands of thousands of blocks. Even if I just render those that are in my immediate neighborhood there are hundreds of them and (at least with the debugRenderer) I drop to 1 fps really quickly (on my own "monster machine"). I thought about strategies like creating just one body, attaching multiple fixtures and only if a fixture got hit, separate it from the body, create a new one and destroy it, but this didn't turn out quite as successful as hoped. (In fact the core just dumps. Ah hello C! I really missed you :X) Here is the code: public class Box2DGameScreen implements Screen { private World world; private Box2DDebugRenderer debugRenderer; private OrthographicCamera camera; private final float TIMESTEP = 1 / 60f; // 1/60 of a second -> 1 frame per second private final int VELOCITYITERATIONS = 8; private final int POSITIONITERATIONS = 3; private Map map; private BodyDef blockBodyDef; private FixtureDef blockFixtureDef; private BodyDef groundDef; private Body ground; private PolygonShape rectangleShape; @Override public void show() { world = new World(new Vector2(0, -9.81f), true); debugRenderer = new Box2DDebugRenderer(); camera = new OrthographicCamera(); // Pixel:Meter = 16:1 // Body definition BodyDef ballDef = new BodyDef(); ballDef.type = BodyDef.BodyType.DynamicBody; ballDef.position.set(0, 1); // Fixture definition FixtureDef ballFixtureDef = new FixtureDef(); ballFixtureDef.shape = new CircleShape(); ballFixtureDef.shape.setRadius(.5f); // 0,5 meter ballFixtureDef.restitution = 0.75f; // between 0 (not jumping up at all) and 1 (jumping up the same amount as it fell down) ballFixtureDef.density = 2.5f; // kg / m² ballFixtureDef.friction = 0.25f; // between 0 (sliding like ice) and 1 (not sliding) // world.createBody(ballDef).createFixture(ballFixtureDef); groundDef = new BodyDef(); groundDef.type = BodyDef.BodyType.StaticBody; groundDef.position.set(0, 0); ground = world.createBody(groundDef); this.map = new Map(20, 20); rectangleShape = new PolygonShape(); // rectangleShape.setAsBox(1, 1); blockFixtureDef = new FixtureDef(); // blockFixtureDef.shape = rectangleShape; blockFixtureDef.restitution = 0.1f; blockFixtureDef.density = 10f; blockFixtureDef.friction = 0.9f; } @Override public void render(float delta) { Gdx.gl.glClearColor(1, 1, 1, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); debugRenderer.render(world, camera.combined); drawMap(); world.step(TIMESTEP, VELOCITYITERATIONS, POSITIONITERATIONS); } private void drawMap() { for(int a = 0; a < map.getHeight(); a++) { /* if(camera.position.y - (camera.viewportHeight/2) > a) continue; if(camera.position.y - (camera.viewportHeight/2) < a) break; */ for(int b = 0; b < map.getWidth(); b++) { /* if(camera.position.x - (camera.viewportWidth/2) > b) continue; if(camera.position.x - (camera.viewportWidth/2) < b) break; */ /* blockBodyDef = new BodyDef(); blockBodyDef.type = BodyDef.BodyType.StaticBody; blockBodyDef.position.set(b, a); world.createBody(blockBodyDef).createFixture(blockFixtureDef); */ PolygonShape rectangleShape = new PolygonShape(); rectangleShape.setAsBox(1, 1, new Vector2(b, a), 0); blockFixtureDef.shape = rectangleShape; ground.createFixture(blockFixtureDef); rectangleShape.dispose(); } } } @Override public void resize(int width, int height) { camera.viewportWidth = width / 16; camera.viewportHeight = height / 16; camera.update(); } @Override public void hide() { dispose(); } @Override public void pause() { } @Override public void resume() { } @Override public void dispose() { world.dispose(); debugRenderer.dispose(); } } As you can see I'm facing multiple problems here. I'm not quite sure how to check for the bounds but also if the map is bigger than 24*24 like 1024*256 Java just crashes -.-. And with 24*24 I get like 9 fps. So I'm doing something really terrible here, it seems and I assume that there most be a (much more performant) way, even with Box2D's awesome physics. Any other ideas? Thanks in advance!

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  • 10000's+ UI elements, bind or draw?

    - by jpiccolo
    I am drawing a header for a timeline control. It looks like this: I go to 0.01 millisecond per line, so for a 10 minute timeline I am looking at drawing 60000 lines + 6000 labels. This takes a while, ~10 seconds. I would like to offload this from the UI thread. My code is currently: private void drawHeader() { Header.Children.Clear(); switch (viewLevel) { case ViewLevel.MilliSeconds100: double hWidth = Header.Width; this.drawHeaderLines(new TimeSpan(0, 0, 0, 0, 10), 100, 5, hWidth); //Was looking into background worker to off load UI //backgroundWorker = new BackgroundWorker(); //backgroundWorker.DoWork += delegate(object sender, DoWorkEventArgs args) // { // this.drawHeaderLines(new TimeSpan(0, 0, 0, 0, 10), 100, 5, hWidth); // }; //backgroundWorker.RunWorkerAsync(); break; } } private void drawHeaderLines(TimeSpan timeStep, int majorEveryXLine, int distanceBetweenLines, double headerWidth) { var currentTime = new TimeSpan(0, 0, 0, 0, 0); const int everyXLine100 = 10; double currentX = 0; var currentLine = 0; while (currentX < headerWidth) { var l = new Line { ToolTip = currentTime.ToString(@"hh\:mm\:ss\.fff"), StrokeThickness = 1, X1 = 0, X2 = 0, Y1 = 30, Y2 = 25 }; if (((currentLine % majorEveryXLine) == 0) && currentLine != 0) { l.StrokeThickness = 2; l.Y2 = 15; var textBlock = new TextBlock { Text = l.ToolTip.ToString(), FontSize = 8, FontFamily = new FontFamily("Tahoma"), Foreground = new SolidColorBrush(Color.FromRgb(255, 255, 255)) }; Canvas.SetLeft(textBlock, (currentX - 22)); Canvas.SetTop(textBlock, 0); Header.Children.Add(textBlock); } if ((((currentLine % everyXLine100) == 0) && currentLine != 0) && (currentLine % majorEveryXLine) != 0) { l.Y2 = 20; var textBlock = new TextBlock { Text = string.Format(".{0}", TimeSpan.Parse(l.ToolTip.ToString()).Milliseconds), FontSize = 8, FontFamily = new FontFamily("Tahoma"), Foreground = new SolidColorBrush(Color.FromRgb(192, 192, 192)) }; Canvas.SetLeft(textBlock, (currentX - 8)); Canvas.SetTop(textBlock, 8); Header.Children.Add(textBlock); } l.Stroke = new SolidColorBrush(Color.FromRgb(255, 255, 255)); Header.Children.Add(l); Canvas.SetLeft(l, currentX); currentX += distanceBetweenLines; currentLine++; currentTime += timeStep; } } I had looked into BackgroundWorker, except you can't create UI elements on a non-UI thread. Is it possible at all to do drawHeaderLines in a non-UI thread? Could I use data binding for drawing the lines? Would this help with UI responsiveness? I would imagine I can use databinding, but the Styling is probably beyond my current WPF ability (coming from winforms and trying to learn what all these style objects are and binding them). Would anyone be able to supply a starting point for tempting this out? Or Google a tutorial that would get me started?

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  • Input handling between game loops

    - by user48023
    This may be obvious and trivial for you but as I am a newbie in programming I come with a specific question. I have three loops in my game engine which are input-loop, update-loop and render-loop. Update-loop is set to 10 ticks per second with a fixed timestep, render-loop is capped at around 60 fps and the input-loop runs as fast as possible. I am using one of the Javascript frameworks which provide such things but it doesn't really matter. Let's say I am rendering a tile map and the view of which elements are rendered depends on camera-like movement variables which are modified during key pressing. This is only about camera/viewport and rendering, no game physics involved here. And now, how can I handle input events among these loops to keep consistent engine reaction? Am I supposed to read the current variable modified with input and do some needed calculations in a update-loop and share the result so it could be interpolated in a render-loop? Or read the input effect directly inside the render-loop and put needed calculations inside? I thought interpreting user input inside an update-loop with a low tick rate would be inaccurate and kind of unresponsive while rendering with interpolation in the final view. How it is done properly in games overall?

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  • Why does my game loop speed vary on different platforms with the same hardware?

    - by Sri Harsha Chilakapati
    I've got a serious issue with my game loop. This loop varies in time with the platform and with the same hardware. This is a list of FPS achieved: - Windows ======= 140 to 150 - Linux ======= 120 to 125 - Windows(WINE) ======= 125 to 135 And since my game loop is fixed timestep, the speed of the game is not stable. Here's my game loop. public final void run() { // Initialize the resources Map.initMap(); initResources(); // Start the timer GTimer.startTimer(); GTimer.refresh(); long elapsedTime = 0; // The game loop while (running) { // Update the game update(elapsedTime); if (state == GameState.GAME_PLAYING) { Map.updateObjects(elapsedTime); } // Show or hide the cursor if (Global.HIDE_CURSOR) { setCursor(GInput.INVISIBLE_CURSOR); } else { setCursor(Cursor.getDefaultCursor()); } // Repaint the game and sync repaint(); elapsedTime = GTimer.sync(); Toolkit.getDefaultToolkit().sync(); } } The timer package How could I improve it?

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  • Should I amortize scripting cost via bytecode analysis or multithreading?

    - by user18983
    I'm working on a game sort of thing where users can write arbitrary code for individual agents, and I'm trying to decide the best way to divide up computation time. The simplest option would be to give each agent a set amount of time and skip their turn if it elapses without an action being decided upon, but I would like people to be able to write their agents decision functions without having to think too much about how long its taking unless they really want to. The two approaches I'm considering are giving each agent a set number of bytecode instructions (taking cost into account) each timestep, and making players deal with the consequences of the game state changing between blocks of computation (as with Battlecode) or giving each agent it's own thread and giving each thread equal time on the processor. I'm about equally knowledgeable on both concurrency and bytecode stuff, which is to say not very, so I'm wondering which approach would be best. I have a clearer idea of how I'd structure things if I used bytecode, but less certainty about how to actually implement the analysis. I'm pretty sure I can work up a concurrency based system without much trouble, but I worry it will be messier with more overhead and will add unnecessary complexity to the project.

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  • Issues with HLSL and lighting

    - by numerical25
    I am trying figure out whats going on with my HLSL code but I have no way of debugging it cause C++ gives off no errors. The application just closes when I run it. I am trying to add lighting to a 3d plane I made. below is my HLSL. The problem consist when my Pixel shader method returns the struct "outColor" . If I change the return value back to the struct "psInput" , everything goes back to working again. My light vectors and colors are at the top of the fx file // PS_INPUT - input variables to the pixel shader // This struct is created and fill in by the // vertex shader cbuffer Variables { matrix Projection; matrix World; float TimeStep; }; struct PS_INPUT { float4 Pos : SV_POSITION; float4 Color : COLOR0; float3 Normal : TEXCOORD0; float3 ViewVector : TEXCOORD1; }; float specpower = 80.0f; float3 camPos = float3(0.0f, 9.0, -256.0f); float3 DirectLightColor = float3(1.0f, 1.0f, 1.0f); float3 DirectLightVector = float3(0.0f, 0.602f, 0.70f); float3 AmbientLightColor = float3(1.0f, 1.0f, 1.0f); /*************************************** * Lighting functions ***************************************/ /********************************* * CalculateAmbient - * inputs - * vKa material's reflective color * lightColor - the ambient color of the lightsource * output - ambient color *********************************/ float3 CalculateAmbient(float3 vKa, float3 lightColor) { float3 vAmbient = vKa * lightColor; return vAmbient; } /********************************* * CalculateDiffuse - * inputs - * material color * The color of the direct light * the local normal * the vector of the direct light * output - difuse color *********************************/ float3 CalculateDiffuse(float3 baseColor, float3 lightColor, float3 normal, float3 lightVector) { float3 vDiffuse = baseColor * lightColor * saturate(dot(normal, lightVector)); return vDiffuse; } /********************************* * CalculateSpecular - * inputs - * viewVector * the direct light vector * the normal * output - specular highlight *********************************/ float CalculateSpecular(float3 viewVector, float3 lightVector, float3 normal) { float3 vReflect = reflect(lightVector, normal); float fSpecular = saturate(dot(vReflect, viewVector)); fSpecular = pow(fSpecular, specpower); return fSpecular; } /********************************* * LightingCombine - * inputs - * ambient component * diffuse component * specualr component * output - phong color color *********************************/ float3 LightingCombine(float3 vAmbient, float3 vDiffuse, float fSpecular) { float3 vCombined = vAmbient + vDiffuse + fSpecular.xxx; return vCombined; } //////////////////////////////////////////////// // Vertex Shader - Main Function /////////////////////////////////////////////// PS_INPUT VS(float4 Pos : POSITION, float4 Color : COLOR, float3 Normal : NORMAL) { PS_INPUT psInput; float4 newPosition; newPosition = Pos; newPosition.y = sin((newPosition.x * TimeStep) + (newPosition.z / 3.0f)) * 5.0f; // Pass through both the position and the color psInput.Pos = mul(newPosition , Projection ); psInput.Color = Color; psInput.ViewVector = normalize(camPos - psInput.Pos); return psInput; } /////////////////////////////////////////////// // Pixel Shader /////////////////////////////////////////////// //Anthony!!!!!!!!!!! Find out how color works when multiplying them float4 PS(PS_INPUT psInput) : SV_Target { float3 normal = -normalize(psInput.Normal); float3 vAmbient = CalculateAmbient(psInput.Color, AmbientLightColor); float3 vDiffuse = CalculateDiffuse(psInput.Color, DirectLightColor, normal, DirectLightVector); float fSpecular = CalculateSpecular(psInput.ViewVector, DirectLightVector, normal); float4 outColor; outColor.rgb = LightingCombine(vAmbient, vDiffuse, fSpecular); outColor.a = 1.0f; //Below is where the error begins return outColor; } // Define the technique technique10 Render { pass P0 { SetVertexShader( CompileShader( vs_4_0, VS() ) ); SetGeometryShader( NULL ); SetPixelShader( CompileShader( ps_4_0, PS() ) ); } } Below is some of my c++ code. Reason I am showing this is because it is pretty much what creates the surface normals for my shaders to evaluate. for the lighting for(int z=0; z < NUM_ROWS; ++z) { for(int x = 0; x < NUM_COLS; ++x) { int curVertex = x + (z * NUM_VERTSX); indices[curIndex] = curVertex; indices[curIndex + 1] = curVertex + NUM_VERTSX; indices[curIndex + 2] = curVertex + 1; D3DXVECTOR3 v0 = vertices[indices[curIndex]].pos; D3DXVECTOR3 v1 = vertices[indices[curIndex + 1]].pos; D3DXVECTOR3 v2 = vertices[indices[curIndex + 2]].pos; D3DXVECTOR3 normal; D3DXVECTOR3 cross; D3DXVec3Cross(&cross, &D3DXVECTOR3(v2 - v0),&D3DXVECTOR3(v1 - v0)); D3DXVec3Normalize(&normal, &cross); vertices[indices[curIndex]].normal = normal; vertices[indices[curIndex + 1]].normal = normal; vertices[indices[curIndex + 2]].normal = normal; indices[curIndex + 3] = curVertex + 1; indices[curIndex + 4] = curVertex + NUM_VERTSX; indices[curIndex + 5] = curVertex + NUM_VERTSX + 1; v0 = vertices[indices[curIndex + 3]].pos; v1 = vertices[indices[curIndex + 4]].pos; v2 = vertices[indices[curIndex + 5]].pos; D3DXVec3Cross(&cross, &D3DXVECTOR3(v2 - v0),&D3DXVECTOR3(v1 - v0)); D3DXVec3Normalize(&normal, &cross); vertices[indices[curIndex + 3]].normal = normal; vertices[indices[curIndex + 4]].normal = normal; vertices[indices[curIndex + 5]].normal = normal; curIndex += 6; } } and below is my c++ code, in it's entirety. showing the drawing and also calling on the passes #include "MyGame.h" //#include "CubeVector.h" /* This code sets a projection and shows a turning cube. What has been added is the project, rotation and a rasterizer to change the rasterization of the cube. The issue that was going on was something with the effect file which was causing the vertices not to be rendered correctly.*/ typedef struct { ID3D10Effect* pEffect; ID3D10EffectTechnique* pTechnique; //vertex information ID3D10Buffer* pVertexBuffer; ID3D10Buffer* pIndicesBuffer; ID3D10InputLayout* pVertexLayout; UINT numVertices; UINT numIndices; }ModelObject; ModelObject modelObject; // World Matrix D3DXMATRIX WorldMatrix; // View Matrix D3DXMATRIX ViewMatrix; // Projection Matrix D3DXMATRIX ProjectionMatrix; ID3D10EffectMatrixVariable* pProjectionMatrixVariable = NULL; //grid information #define NUM_COLS 16 #define NUM_ROWS 16 #define CELL_WIDTH 32 #define CELL_HEIGHT 32 #define NUM_VERTSX (NUM_COLS + 1) #define NUM_VERTSY (NUM_ROWS + 1) // timer variables LARGE_INTEGER timeStart; LARGE_INTEGER timeEnd; LARGE_INTEGER timerFreq; double currentTime; float anim_rate; // Variable to hold how long since last frame change float lastElaspedFrame = 0; // How long should the frames last float frameDuration = 0.5; bool MyGame::InitDirect3D() { if(!DX3dApp::InitDirect3D()) { return false; } // Get the timer frequency QueryPerformanceFrequency(&timerFreq); float freqSeconds = 1.0f / timerFreq.QuadPart; lastElaspedFrame = 0; D3D10_RASTERIZER_DESC rastDesc; rastDesc.FillMode = D3D10_FILL_WIREFRAME; rastDesc.CullMode = D3D10_CULL_FRONT; rastDesc.FrontCounterClockwise = true; rastDesc.DepthBias = false; rastDesc.DepthBiasClamp = 0; rastDesc.SlopeScaledDepthBias = 0; rastDesc.DepthClipEnable = false; rastDesc.ScissorEnable = false; rastDesc.MultisampleEnable = false; rastDesc.AntialiasedLineEnable = false; ID3D10RasterizerState *g_pRasterizerState; mpD3DDevice->CreateRasterizerState(&rastDesc, &g_pRasterizerState); mpD3DDevice->RSSetState(g_pRasterizerState); // Set up the World Matrix D3DXMatrixIdentity(&WorldMatrix); D3DXMatrixLookAtLH(&ViewMatrix, new D3DXVECTOR3(200.0f, 60.0f, -20.0f), new D3DXVECTOR3(200.0f, 50.0f, 0.0f), new D3DXVECTOR3(0.0f, 1.0f, 0.0f)); // Set up the projection matrix D3DXMatrixPerspectiveFovLH(&ProjectionMatrix, (float)D3DX_PI * 0.5f, (float)mWidth/(float)mHeight, 0.1f, 100.0f); pTimeVariable = NULL; if(!CreateObject()) { return false; } return true; } //These are actions that take place after the clearing of the buffer and before the present void MyGame::GameDraw() { static float rotationAngle = 0.0f; // create the rotation matrix using the rotation angle D3DXMatrixRotationY(&WorldMatrix, rotationAngle); rotationAngle += (float)D3DX_PI * 0.0f; // Set the input layout mpD3DDevice->IASetInputLayout(modelObject.pVertexLayout); // Set vertex buffer UINT stride = sizeof(VertexPos); UINT offset = 0; mpD3DDevice->IASetVertexBuffers(0, 1, &modelObject.pVertexBuffer, &stride, &offset); mpD3DDevice->IASetIndexBuffer(modelObject.pIndicesBuffer, DXGI_FORMAT_R32_UINT, 0); pTimeVariable->SetFloat((float)currentTime); // Set primitive topology mpD3DDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST); // Combine and send the final matrix to the shader D3DXMATRIX finalMatrix = (WorldMatrix * ViewMatrix * ProjectionMatrix); pProjectionMatrixVariable->SetMatrix((float*)&finalMatrix); // make sure modelObject is valid // Render a model object D3D10_TECHNIQUE_DESC techniqueDescription; modelObject.pTechnique->GetDesc(&techniqueDescription); // Loop through the technique passes for(UINT p=0; p < techniqueDescription.Passes; ++p) { modelObject.pTechnique->GetPassByIndex(p)->Apply(0); // draw the cube using all 36 vertices and 12 triangles mpD3DDevice->DrawIndexed(modelObject.numIndices,0,0); } } //Render actually incapsulates Gamedraw, so you can call data before you actually clear the buffer or after you //present data void MyGame::Render() { // Get the start timer count QueryPerformanceCounter(&timeStart); currentTime += anim_rate; DX3dApp::Render(); QueryPerformanceCounter(&timeEnd); anim_rate = ( (float)timeEnd.QuadPart - (float)timeStart.QuadPart ) / timerFreq.QuadPart; } bool MyGame::CreateObject() { VertexPos vertices[NUM_VERTSX * NUM_VERTSY]; for(int z=0; z < NUM_VERTSY; ++z) { for(int x = 0; x < NUM_VERTSX; ++x) { vertices[x + z * NUM_VERTSX].pos.x = (float)x * CELL_WIDTH; vertices[x + z * NUM_VERTSX].pos.z = (float)z * CELL_HEIGHT; vertices[x + z * NUM_VERTSX].pos.y = (float)(rand() % CELL_HEIGHT); vertices[x + z * NUM_VERTSX].color = D3DXVECTOR4(1.0, 0.0f, 0.0f, 0.0f); } } DWORD indices[NUM_VERTSX * NUM_VERTSY * 6]; int curIndex = 0; for(int z=0; z < NUM_ROWS; ++z) { for(int x = 0; x < NUM_COLS; ++x) { int curVertex = x + (z * NUM_VERTSX); indices[curIndex] = curVertex; indices[curIndex + 1] = curVertex + NUM_VERTSX; indices[curIndex + 2] = curVertex + 1; D3DXVECTOR3 v0 = vertices[indices[curIndex]].pos; D3DXVECTOR3 v1 = vertices[indices[curIndex + 1]].pos; D3DXVECTOR3 v2 = vertices[indices[curIndex + 2]].pos; D3DXVECTOR3 normal; D3DXVECTOR3 cross; D3DXVec3Cross(&cross, &D3DXVECTOR3(v2 - v0),&D3DXVECTOR3(v1 - v0)); D3DXVec3Normalize(&normal, &cross); vertices[indices[curIndex]].normal = normal; vertices[indices[curIndex + 1]].normal = normal; vertices[indices[curIndex + 2]].normal = normal; indices[curIndex + 3] = curVertex + 1; indices[curIndex + 4] = curVertex + NUM_VERTSX; indices[curIndex + 5] = curVertex + NUM_VERTSX + 1; v0 = vertices[indices[curIndex + 3]].pos; v1 = vertices[indices[curIndex + 4]].pos; v2 = vertices[indices[curIndex + 5]].pos; D3DXVec3Cross(&cross, &D3DXVECTOR3(v2 - v0),&D3DXVECTOR3(v1 - v0)); D3DXVec3Normalize(&normal, &cross); vertices[indices[curIndex + 3]].normal = normal; vertices[indices[curIndex + 4]].normal = normal; vertices[indices[curIndex + 5]].normal = normal; curIndex += 6; } } //Create Layout D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"NORMAL",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 28, D3D10_INPUT_PER_VERTEX_DATA, 0} }; UINT numElements = (sizeof(layout)/sizeof(layout[0])); modelObject.numVertices = sizeof(vertices)/sizeof(VertexPos); //Create buffer desc D3D10_BUFFER_DESC bufferDesc; bufferDesc.Usage = D3D10_USAGE_DEFAULT; bufferDesc.ByteWidth = sizeof(VertexPos) * modelObject.numVertices; bufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER; bufferDesc.CPUAccessFlags = 0; bufferDesc.MiscFlags = 0; D3D10_SUBRESOURCE_DATA initData; initData.pSysMem = vertices; //Create the buffer HRESULT hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pVertexBuffer); if(FAILED(hr)) return false; modelObject.numIndices = sizeof(indices)/sizeof(DWORD); bufferDesc.ByteWidth = sizeof(DWORD) * modelObject.numIndices; bufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER; initData.pSysMem = indices; hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pIndicesBuffer); if(FAILED(hr)) return false; ///////////////////////////////////////////////////////////////////////////// //Set up fx files LPCWSTR effectFilename = L"effect.fx"; modelObject.pEffect = NULL; hr = D3DX10CreateEffectFromFile(effectFilename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, mpD3DDevice, NULL, NULL, &modelObject.pEffect, NULL, NULL); if(FAILED(hr)) return false; pProjectionMatrixVariable = modelObject.pEffect->GetVariableByName("Projection")->AsMatrix(); pTimeVariable = modelObject.pEffect->GetVariableByName("TimeStep")->AsScalar(); //Dont sweat the technique. Get it! LPCSTR effectTechniqueName = "Render"; modelObject.pTechnique = modelObject.pEffect->GetTechniqueByName(effectTechniqueName); if(modelObject.pTechnique == NULL) return false; //Create Vertex layout D3D10_PASS_DESC passDesc; modelObject.pTechnique->GetPassByIndex(0)->GetDesc(&passDesc); hr = mpD3DDevice->CreateInputLayout(layout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, &modelObject.pVertexLayout); if(FAILED(hr)) return false; return true; }

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  • Pseudorandom Number Generation with Specific Non-Uniform Distributions

    - by carnun
    Hello all, I'm writing a program that simulates various random walks (with differing distributions). At each timestep, I need randomly generated, two dimensional step distances and angles from the distribution of the random walk. I'm hoping someone can check my understanding of how to generate these random numbers. As I understand it I can use Inverse Transform Sampling as follows: If f(x) is the pdf of our random walk that has a non-uniform distribution, and y is a random number from a uniform distribution. Then if we let f(x) = y and solve to find x then we have a random number from the non-uniform distribution. Is this a feasible solution?

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  • Understanding and Implementing a Force based graph layout algorithm

    - by zcourts
    I'm trying to implement a force base graph layout algorithm, based on http://en.wikipedia.org/wiki/Force-based_algorithms_(graph_drawing) My first attempt didn't work so I looked at http://blog.ivank.net/force-based-graph-drawing-in-javascript.html and https://github.com/dhotson/springy I changed my implementation based on what I thought I understood from those two but I haven't managed to get it right and I'm hoping someone can help? JavaScript isn't my strong point so be gentle... If you're wondering why write my own. In reality I have no real reason to write my own I'm just trying to understand how the algorithm is implemented. Especially in my first link, that demo is brilliant. This is what I've come up with //support function.bind - https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind#Compatibility if (!Function.prototype.bind) { Function.prototype.bind = function (oThis) { if (typeof this !== "function") { // closest thing possible to the ECMAScript 5 internal IsCallable function throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable"); } var aArgs = Array.prototype.slice.call(arguments, 1), fToBind = this, fNOP = function () {}, fBound = function () { return fToBind.apply(this instanceof fNOP ? this : oThis || window, aArgs.concat(Array.prototype.slice.call(arguments))); }; fNOP.prototype = this.prototype; fBound.prototype = new fNOP(); return fBound; }; } (function() { var lastTime = 0; var vendors = ['ms', 'moz', 'webkit', 'o']; for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) { window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame']; window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame'] || window[vendors[x]+'CancelRequestAnimationFrame']; } if (!window.requestAnimationFrame) window.requestAnimationFrame = function(callback, element) { var currTime = new Date().getTime(); var timeToCall = Math.max(0, 16 - (currTime - lastTime)); var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall); lastTime = currTime + timeToCall; return id; }; if (!window.cancelAnimationFrame) window.cancelAnimationFrame = function(id) { clearTimeout(id); }; }()); function Graph(o){ this.options=o; this.vertices={}; this.edges={};//form {vertexID:{edgeID:edge}} } /** *Adds an edge to the graph. If the verticies in this edge are not already in the *graph then they are added */ Graph.prototype.addEdge=function(e){ //if vertex1 and vertex2 doesn't exist in this.vertices add them if(typeof(this.vertices[e.vertex1])==='undefined') this.vertices[e.vertex1]=new Vertex(e.vertex1); if(typeof(this.vertices[e.vertex2])==='undefined') this.vertices[e.vertex2]=new Vertex(e.vertex2); //add the edge if(typeof(this.edges[e.vertex1])==='undefined') this.edges[e.vertex1]={}; this.edges[e.vertex1][e.id]=e; } /** * Add a vertex to the graph. If a vertex with the same ID already exists then * the existing vertex's .data property is replaced with the @param v.data */ Graph.prototype.addVertex=function(v){ if(typeof(this.vertices[v.id])==='undefined') this.vertices[v.id]=v; else this.vertices[v.id].data=v.data; } function Vertex(id,data){ this.id=id; this.data=data?data:{}; //initialize to data.[x|y|z] or generate random number for each this.x = this.data.x?this.data.x:-100 + Math.random()*200; this.y = this.data.y?this.data.y:-100 + Math.random()*200; this.z = this.data.y?this.data.y:-100 + Math.random()*200; //set initial velocity to 0 this.velocity = new Point(0, 0, 0); this.mass=this.data.mass?this.data.mass:Math.random(); this.force=new Point(0,0,0); } function Edge(vertex1ID,vertex2ID){ vertex1ID=vertex1ID?vertex1ID:Math.random() vertex2ID=vertex2ID?vertex2ID:Math.random() this.id=vertex1ID+"->"+vertex2ID; this.vertex1=vertex1ID; this.vertex2=vertex2ID; } function Point(x, y, z) { this.x = x; this.y = y; this.z = z; } Point.prototype.plus=function(p){ this.x +=p.x this.y +=p.y this.z +=p.z } function ForceLayout(o){ this.repulsion = o.repulsion?o.repulsion:200; this.attraction = o.attraction?o.attraction:0.06; this.damping = o.damping?o.damping:0.9; this.graph = o.graph?o.graph:new Graph(); this.total_kinetic_energy =0; this.animationID=-1; } ForceLayout.prototype.draw=function(){ //vertex velocities initialized to (0,0,0) when a vertex is created //vertex positions initialized to random position when created cc=0; do{ this.total_kinetic_energy =0; //for each vertex for(var i in this.graph.vertices){ var thisNode=this.graph.vertices[i]; // running sum of total force on this particular node var netForce=new Point(0,0,0) //for each other node for(var j in this.graph.vertices){ if(thisNode!=this.graph.vertices[j]){ //net-force := net-force + Coulomb_repulsion( this_node, other_node ) netForce.plus(this.CoulombRepulsion( thisNode,this.graph.vertices[j])) } } //for each spring connected to this node for(var k in this.graph.edges[thisNode.id]){ //(this node, node its connected to) //pass id of this node and the node its connected to so hookesattraction //can update the force on both vertices and return that force to be //added to the net force this.HookesAttraction(thisNode.id, this.graph.edges[thisNode.id][k].vertex2 ) } // without damping, it moves forever // this_node.velocity := (this_node.velocity + timestep * net-force) * damping thisNode.velocity.x=(thisNode.velocity.x+thisNode.force.x)*this.damping; thisNode.velocity.y=(thisNode.velocity.y+thisNode.force.y)*this.damping; thisNode.velocity.z=(thisNode.velocity.z+thisNode.force.z)*this.damping; //this_node.position := this_node.position + timestep * this_node.velocity thisNode.x=thisNode.velocity.x; thisNode.y=thisNode.velocity.y; thisNode.z=thisNode.velocity.z; //normalize x,y,z??? //total_kinetic_energy := total_kinetic_energy + this_node.mass * (this_node.velocity)^2 this.total_kinetic_energy +=thisNode.mass*((thisNode.velocity.x+thisNode.velocity.y+thisNode.velocity.z)* (thisNode.velocity.x+thisNode.velocity.y+thisNode.velocity.z)) } cc+=1; }while(this.total_kinetic_energy >0.5) console.log(cc,this.total_kinetic_energy,this.graph) this.cancelAnimation(); } ForceLayout.prototype.HookesAttraction=function(v1ID,v2ID){ var a=this.graph.vertices[v1ID] var b=this.graph.vertices[v2ID] var force=new Point(this.attraction*(b.x - a.x),this.attraction*(b.y - a.y),this.attraction*(b.z - a.z)) // hook's attraction a.force.x += force.x; a.force.y += force.y; a.force.z += force.z; b.force.x += this.attraction*(a.x - b.x); b.force.y += this.attraction*(a.y - b.y); b.force.z += this.attraction*(a.z - b.z); return force; } ForceLayout.prototype.CoulombRepulsion=function(vertex1,vertex2){ //http://en.wikipedia.org/wiki/Coulomb's_law // distance squared = ((x1-x2)*(x1-x2)) + ((y1-y2)*(y1-y2)) + ((z1-z2)*(z1-z2)) var distanceSquared = ( (vertex1.x-vertex2.x)*(vertex1.x-vertex2.x)+ (vertex1.y-vertex2.y)*(vertex1.y-vertex2.y)+ (vertex1.z-vertex2.z)*(vertex1.z-vertex2.z) ); if(distanceSquared==0) distanceSquared = 0.001; var coul = this.repulsion / distanceSquared; return new Point(coul * (vertex1.x-vertex2.x),coul * (vertex1.y-vertex2.y), coul * (vertex1.z-vertex2.z)); } ForceLayout.prototype.animate=function(){ if(this.animating) this.animationID=requestAnimationFrame(this.animate.bind(this)); this.draw(); } ForceLayout.prototype.cancelAnimation=function(){ cancelAnimationFrame(this.animationID); this.animating=false; } ForceLayout.prototype.redraw=function(){ this.animating=true; this.animate(); } $(document).ready(function(){ var g= new Graph(); for(var i=0;i<=100;i++){ var v1=new Vertex(Math.random(), {}) var v2=new Vertex(Math.random(), {}) var e1= new Edge(v1.id,v2.id); g.addEdge(e1); } console.log(g); var l=new ForceLayout({ graph:g }); l.redraw(); });

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  • How does interpolation actually work to smooth out an object's movement?

    - by user22241
    I've asked a few similar questions over the past 8 months or so with no real joy, so I am going make the question more general. I have an Android game which is OpenGL ES 2.0. within it I have the following Game Loop: My loop works on a fixed time step principle (dt = 1 / ticksPerSecond) loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ updateLogic(dt); nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; loops++; } render(); My intergration works like this: sprite.posX+=sprite.xVel*dt; sprite.posXDrawAt=sprite.posX*width; Now, everything works pretty much as I would like. I can specify that I would like an object to move across a certain distance (screen width say) in 2.5 seconds and it will do just that. Also because of the frame skipping that I allow in my game loop, I can do this on pretty much any device and it will always take 2.5 seconds. Problem However, the problem is that when a render frame skips, the graphic stutter. It's extremely annoying. If I remove the ability to skip frames, then everything is smooth as you like, but will run at different speeds on different devices. So it's not an option. I'm still not sure why the frame skips, but I would like to point out that this is Nothing to do with poor performance, I've taken the code right back to 1 tiny sprite and no logic (apart from the logic required to move the sprite) and I still get skipped frames. And this is on a Google Nexus 10 tablet (and as mentioned above, I need frame skipping to keep the speed consistent across devices anyway). So, the only other option I have is to use interpolation (or extrapolation), I've read every article there is out there but none have really helped me to understand how it works and all of my attempted implementations have failed. Using one method I was able to get things moving smoothly but it was unworkable because it messed up my collision. I can foresee the same issue with any similar method because the interpolation is passed to (and acted upon within) the rendering method - at render time. So if Collision corrects position (character now standing right next to wall), then the renderer can alter it's position and draw it in the wall. So I'm really confused. People have said that you should never alter an object's position from within the rendering method, but all of the examples online show this. So I'm asking for a push in the right direction, please do not link to the popular game loop articles (deWitters, Fix your timestep, etc) as I've read these multiple times. I'm not asking anyone to write my code for me. Just explain please in simple terms how Interpolation actually works with some examples. I will then go and try to integrate any ideas into my code and will ask more specific questions if need-be further down the line. (I'm sure this is a problem many people struggle with).

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  • AI to move custom-shaped spaceships (shape affecting movement behaviour)

    - by kaoD
    I'm designing a networked turn based 3D-6DOF space fleet combat strategy game which relies heavily on ship customization. Let me explain the game a bit, since you need to know a bit about it to set the question. What I aim for is the ability to create your own fleet of ships with custom shapes and attached modules (propellers, tractor beams...) which would give advantages and disadvantages to each ship, so you have lots of different fleet distributions. E.g., long ship with two propellers at the side would let the ship spin around that plane easily, bigger ships would move slowly unless you place lots of propellers at the back (therefore spending more "construction" points and energy when moving, and it will only move fast towards that direction.) I plan to balance all the game around this feature. The game would revolve around two phases: orders and combat phase. During the orders phase, you command the different ships. When all players finish the order phase, the combat phase begins and the ship orders get resolved in real-time for some time, then the action pauses and there's a new orders phase. The problem comes when I think about player input. To move a ship, you need to turn on or off different propellers if you want to steer, travel forward, brake, rotate in place... These propellers don't have to work at their whole power, so you can achieve more movement combinations with less propellers. I think this approach is a bit boring. The player doesn't want to fiddle with motors or anything, you just want to MOVE and KILL. The way I intend the player to give orders to these ships is by a destination and a rotation, and then the AI would calculate the correct propeller power to achive that movement and rotation. Propulsion doesn't have to be the same throught the entire turn calculation (after the orders have been given) so it would be cool if the ships reacted as they move, adjusting the power of the propellers for their needs dynamically, but it may be too hard to implement and it's not really needed for the game to work. In both cases, how would that AI decide which propellers to activate for the best (or at least not worst) trajectory to be achieved? I though about some approaches: Learning AI: The ship types would learn about their movement by trial and error, adjusting their behaviour with more uses, and finally becoming "smart". I don't want to get involved THAT far in AI coding, and I think it can be frustrating for the player (even if you can let it learn without playing.) Pre-calculated timestep movement: Upon ship creation, ALL possible movements are calculated for each propeller configuration and power for a given delta-time. Memory intensive, ugly, bad. Pre-calculated trajectories: The same as above but not for each delta-time but the whole trajectory, which would then be fitted as much as possible. Requires a fixed propeller configuration for the whole combat phase and is still memory intensive, ugly and bad. Continuous brute forcing: The AI continously checks ALL possible propeller configurations throughout the entire combat phase, precalculates a few time steps and decides which is the best one based on that. Con: what's good now might not be that good later, and it's too CPU intensive, ugly, and bad too. Single brute forcing: Same as above, but only brute forcing at the beginning of the simulation, so it needs constant propeller configuration throughout the entire combat phase. Coninuous angle check: This is not a full movement method, but maybe a way to discard "stupid" propeller configurations. Given the current propeller's normal vector and the final one, you can approximate the power needed for the propeller based on the angle. You must do this continuously throughout the whole combat phase. I figured this one out recently so I didn't put in too much thought. A priori, it has the "what's good now might not be that good later" drawback too, and it doesn't care about the other propellers which may act together to make a better propelling configuration. I'm really stuck here. Any ideas?

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  • Parallel version of loop not faster than serial version

    - by Il-Bhima
    I'm writing a program in C++ to perform a simulation of particular system. For each timestep, the biggest part of the execution is taking up by a single loop. Fortunately this is embarassingly parallel, so I decided to use Boost Threads to parallelize it (I'm running on a 2 core machine). I would expect at speedup close to 2 times the serial version, since there is no locking. However I am finding that there is no speedup at all. I implemented the parallel version of the loop as follows: Wake up the two threads (they are blocked on a barrier). Each thread then performs the following: Atomically fetch and increment a global counter. Retrieve the particle with that index. Perform the computation on that particle, storing the result in a separate array Wait on a job finished barrier The main thread waits on the job finished barrier. I used this approach since it should provide good load balancing (since each computation may take differing amounts of time). I am really curious as to what could possibly cause this slowdown. I always read that atomic variables are fast, but now I'm starting to wonder whether they have their performance costs. If anybody has some ideas what to look for or any hints I would really appreciate it. I've been bashing my head on it for a week, and profiling has not revealed much.

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  • How to interpolate in MatLab

    - by G Sam
    I have a 1x1 Matrix of points which specifies speed of a drive with respect to time. This speed changes throughout the operation; which means that the difference between two points is changing. To give you an example: M = [1; 2; 3; 5; 7; 9; 11; 15; 19]. (Only that this is a 892x1 matrix) I want to make this matrix twice as long (so changing the relative speed per timestep), while retaining the way the speeds change. Eg: M' = [1; 1.5; 2; 2.5; 3; 4; 5; 6; 7; 8; 9; 10; 11; 13; 15; 17; 19]. Is there an easy way to do this in MatLab? So far I have tried upsampling (which fills the time step with zeros); interp (which fills it with low-pass interpolation. Thanks!

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  • Python2.7: How can I speed up this bit of code (loop/lists/tuple optimization)?

    - by user89
    I repeat the following idiom again and again. I read from a large file (sometimes, up to 1.2 million records!) and store the output into an SQLite databse. Putting stuff into the SQLite DB seems to be fairly fast. def readerFunction(recordSize, recordFormat, connection, outputDirectory, outputFile, numObjects): insertString = "insert into NODE_DISP_INFO(node, analysis, timeStep, H1_translation, H2_translation, V_translation, H1_rotation, H2_rotation, V_rotation) values (?, ?, ?, ?, ?, ?, ?, ?, ?)" analysisNumber = int(outputPath[-3:]) outputFileObject = open(os.path.join(outputDirectory, outputFile), "rb") outputFileObject, numberOfRecordsInFileObject = determineNumberOfRecordsInFileObjectGivenRecordSize(recordSize, outputFileObject) numberOfRecordsPerObject = (numberOfRecordsInFileObject//numberOfObjects) loop1StartTime = time.time() for i in range(numberOfRecordsPerObject ): processedRecords = [] loop2StartTime = time.time() for j in range(numberOfObjects): fout = outputFileObject .read(recordSize) processedRecords.append(tuple([j+1, analysisNumber, i] + [x for x in list(struct.unpack(recordFormat, fout))])) loop2EndTime = time.time() print "Time taken to finish loop2: {}".format(loop2EndTime-loop2StartTime) dbInsertStartTime = time.time() connection.executemany(insertString, processedRecords) dbInsertEndTime = time.time() loop1EndTime = time.time() print "Time taken to finish loop1: {}".format(loop1EndTime-loop1StartTime) outputFileObject.close() print "Finished reading output file for analysis {}...".format(analysisNumber) When I run the code, it seems that "loop 2" and "inserting into the database" is where most execution time is spent. Average "loop 2" time is 0.003s, but it is run up to 50,000 times, in some analyses. The time spent putting stuff into the database is about the same: 0.004s. Currently, I am inserting into the database every time after loop2 finishes so that I don't have to deal with running out RAM. What could I do to speed up "loop 2"?

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  • Game loop and time tracking

    - by David Brown
    Maybe I'm just an idiot, but I've been trying to implement a game loop all day and it's just not clicking. I've read literally every article I could find on Google, but the problem is that they all use different timing mechanisms, which makes them difficult to apply to my particular situation (some use milliseconds, other use ticks, etc). Basically, I have a Clock object that updates each time the game loop executes. internal class Clock { public static long Timestamp { get { return Stopwatch.GetTimestamp(); } } public static long Frequency { get { return Stopwatch.Frequency; } } private long _startTime; private long _lastTime; private TimeSpan _totalTime; private TimeSpan _elapsedTime; /// <summary> /// The amount of time that has passed since the first step. /// </summary> public TimeSpan TotalTime { get { return _totalTime; } } /// <summary> /// The amount of time that has passed since the last step. /// </summary> public TimeSpan ElapsedTime { get { return _elapsedTime; } } public Clock() { Reset(); } public void Reset() { _startTime = Timestamp; _lastTime = 0; _totalTime = TimeSpan.Zero; _elapsedTime = TimeSpan.Zero; } public void Tick() { long currentTime = Timestamp; if (_lastTime == 0) _lastTime = currentTime; _totalTime = TimestampToTimeSpan(currentTime - _startTime); _elapsedTime = TimestampToTimeSpan(currentTime - _lastTime); _lastTime = currentTime; } public static TimeSpan TimestampToTimeSpan(long timestamp) { return TimeSpan.FromTicks( (timestamp * TimeSpan.TicksPerSecond) / Frequency); } } I based most of that on the XNA GameClock, but it's greatly simplified. Then, I have a Time class which holds various times that the Update and Draw methods need to know. public class Time { public TimeSpan ElapsedVirtualTime { get; internal set; } public TimeSpan ElapsedRealTime { get; internal set; } public TimeSpan TotalVirtualTime { get; internal set; } public TimeSpan TotalRealTime { get; internal set; } internal Time() { } internal Time(TimeSpan elapsedVirtualTime, TimeSpan elapsedRealTime, TimeSpan totalVirutalTime, TimeSpan totalRealTime) { ElapsedVirtualTime = elapsedVirtualTime; ElapsedRealTime = elapsedRealTime; TotalVirtualTime = totalVirutalTime; TotalRealTime = totalRealTime; } } My main class keeps a single instance of Time, which it should constantly update during the game loop. So far, I have this: private static void Loop() { do { Clock.Tick(); Time.TotalRealTime = Clock.TotalTime; Time.ElapsedRealTime = Clock.ElapsedTime; InternalUpdate(Time); InternalDraw(Time); } while (!_exitRequested); } The real time properties of the time class turn out great. Now I'd like to get a proper update/draw loop working so that the state is updated a variable number of times per frame, but at a fixed timestep. At the same time, the Time.TotalVirtualTime and Time.ElapsedVirtualTime should be updated accordingly. In addition, I intend for this to support multiplayer in the future, in case that makes any difference to the design of the game loop. Any tips or examples on how I could go about implementing this (aside from links to articles)?

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  • Calculus? Need help solving for a time-dependent variable given some other variables.

    - by user451527
    Long story short, I'm making a platform game. I'm not old enough to have taken Calculus yet, so I know not of derivatives or integrals, but I know of them. The desired behavior is for my character to automagically jump when there is a block to either side of him that is above the one he's standing on; for instance, stairs. This way the player can just hold left / right to climb stairs, instead of having to spam the jump key too. The issue is with the way I've implemented jumping; I've decided to go mario-style, and allow the player to hold 'jump' longer to jump higher. To do so, I have a 'jump' variable which is added to the player's Y velocity. The jump variable increases to a set value when the 'jump' key is pressed, and decreases very quickly once the 'jump' key is released, but decreases less quickly so long as you hold the 'jump' key down, thus providing continuous acceleration up as long as you hold 'jump.' This also makes for a nice, flowing jump, rather than a visually jarring, abrupt acceleration. So, in order to account for variable stair height, I want to be able to calculate exactly what value the 'jump' variable should get in order to jump exactly to the height of the stair; preferably no more, no less, though slightly more is permissible. This way the character can jump up steep or shallow flights of stairs without it looking weird or being slow. There are essentially 5 variables in play: h -the height the character needs to jump to reach the stair top<br> j -the jump acceleration variable<br> v -the vertical velocity of the character<br> p -the vertical position of the character<br> d -initial vertical position of the player minus final position<br> Each timestep:<br> j -= 1.5; //the jump variable's deceleration<br> v -= j; //the jump value's influence on vertical speed<br> v *= 0.95; //friction on the vertical speed<br> v += 1; //gravity<br> p += v; //add the vertical speed to the vertical position<br> v-initial is known to be zero<br> v-final is known to be zero<br> p-initial is known<br> p-final is known<br> d is known to be p-initial minus p-final<br> j-final is known to be zero<br> j-initial is unknown<br> Given all of these facts, how can I make an equation that will solve for j? tl;dr How do I Calculus? Much thanks to anyone who's made it this far and decides to plow through this problem.

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