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• Optimized algorithm for line-sphere intersection in GLSL

  - by fernacolo

  Well, hello then! I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way: // The line passes through p1 and p2: vec3 p1 = (...); vec3 p2 = (...); // Sphere center is p3, radius is r: vec3 p3 = (...); float r = ...; float x1 = p1.x; float y1 = p1.y; float z1 = p1.z; float x2 = p2.x; float y2 = p2.y; float z2 = p2.z; float x3 = p3.x; float y3 = p3.y; float z3 = p3.z; float dx = x2 - x1; float dy = y2 - y1; float dz = z2 - z1; float a = dx*dx + dy*dy + dz*dz; float b = 2.0 * (dx * (x1 - x3) + dy * (y1 - y3) + dz * (z1 - z3)); float c = x3*x3 + y3*y3 + z3*z3 + x1*x1 + y1*y1 + z1*z1 - 2.0 * (x3*x1 + y3*y1 + z3*z1) - r*r; float test = b*b - 4.0*a*c; if (test >= 0.0) { // Hit (according to Treebeard, "a fine hit"). float u = (-b - sqrt(test)) / (2.0 * a); vec3 hitp = p1 + u * (p2 - p1); // Now use hitp. } It works perfectly! But it seems slow... I'm new at GLSL. You can answer this questions in two ways: Tell me there is no solution, showing some proof or strong evidence. Tell me about GLSL features (vector APIs, primitive operations) that makes the above algorithm faster, showing some example. Thanks a lot!

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• Displaying and updating score in Android (OpenGL ES 2)

  - by user16547

  I'm using a FrameLayout where I have a GLSurfaceView at the bottom and a few Views on top of it. One of those Views is a TextView that displays the current score. Here's how I'm updating the score TextView based on what happens in my game loop: whenever an event happens that increases the score, I call activity.runOnUiThread(updater), where activity is the activity that has the above FrameLayout (my main game activity) and updater is just a Runnable that increments the score. From my understanding, using runOnUiThread() from the OpenGL thread is standard practice - otherwise you'll get an exception, I can't remember its name. The problem is that there's a very noticeable lag between the event and the score update. For example the character gets a coin, but the coin count is not updated quickly. I tried summing all the score events from my game loop and calling runOnUiThread() only once per loop, but it doesn't seem to make much of a difference - the lag is still noticeable. How can I improve my design to avoid this lag?

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• How do I set an event off when player is on certain tile?

  - by Tom Burman

  Here is the code I use to create and print my map to the canvas: var board = []; function loadMap(map) { if (map == 1) { return [ [2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,3,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,3,0,0,2], [2,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,3,3,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,3,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,3,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,3,0,3,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,3,3,3,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,3,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,0,0,3,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,0,0,0,0,0,0,0,0,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,3,3,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2], [2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2] ]; } } board = loadMap(1); enterfor (y = 0; y <= viewHeight; y++) { for (x = 0; x <= viewWidth; x++) { var theX = x * 32; var theY = y * 32; context.drawImage(mapTiles[board[y+viewY][x+viewX]], theX, theY, 32, 32); } } And here is the code I use for player movement: canvas.addEventListener('keydown', function(e) { console.log(e); var key = null; switch (e.which) { case 37: // Left if (playerX > 0) playerX--; break; case 38: // Up if (playerY > 0) playerY--; break; case 39: // Right if (playerX < worldWidth) playerX++; break; case 40: // Down if (playerY < worldHeight) playerY++; break; } viewX = playerX - Math.floor(0.5 * viewWidth); if (viewX < 0) viewX = 0; if (viewX+viewWidth > worldWidth) viewX = worldWidth - viewWidth; viewY = playerY - Math.floor(0.5 * viewHeight); if (viewY < 0) viewY = 0; if (viewY+viewHeight > worldHeight) viewY = worldHeight - viewHeight; }, false); What I am looking for is a method for when the player lands on tile 3 he loses health. I have tried to use this in the player movement but it doesnt seem to work e.g the left movement: case 37: // Left if (playerX > 0) playerX--; if(board[x2 - 1] == 3) { health--; playerX--; }

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• How can I use WebGL to create a tile-based multi-layer scrolling platform game?

  - by Nicholas Hill

  I've found WebGL (based on OpenGL) to be a fiendish and unforgiving framework for those learning to write HTML5-based games. Despite the presence of many examples on how to get started, I'm really struggling to understand how I could simply load a bunch of images and render them to a canvas quickly using WebGL. My specific scenario involves trying to render a map using a bespoke but simple multi-layered tile engine, where each value in a three dimensional array points to the image to use for that location in the rendered image. Think "Sonic the Hedgehog" via tilesets, tiles, maps, layers, sprites etc. Can anyone enlighten me: 1) How can I load an image that I can use as a texture in WebGL? 2) How can I dynamically select an image at run time and draw it at any co-ordinate, that I also select at run time?

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• Too much delay while sending object over UDP to server

  - by RomZes

  I'm getting 4 sec delay when sending objects over UDP. Working on small game and trying to implement multiplayer. For now just trying to synchronize movements of 2 balls on the screen. StartingPoint.java is my server(first player), that receiving serialized objects (coordinates). SecondPlayer.java is client that sending serialized objects to server. When I'm moving my first object it appears 4 seconds later on different screen. StartingPoint.java @Override public void run() { byte[] receiveData = new byte[256]; byte[] sendData = new byte[256]; // DatagramSocket socketS; try { socket = new DatagramSocket(5000); System.out.println("Socket created on "+ port + " port"); } catch (SocketException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } while(true){ b1.update(this); b3.update(); System.out.println("Starting server..."); //// Receiving and deserializing object try { //socket.setSoTimeout(1000); DatagramPacket packet = new DatagramPacket(buf, buf.length); socket.receive(packet); byte[] data = packet.getData(); ByteArrayInputStream in = new ByteArrayInputStream(data); ObjectInputStream is = new ObjectInputStream(in); // socket.setSoTimeout(300); b1 = (Ball) is.readObject(); } catch (IOException | ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } SecondPlayer.java @Override public void run() { while(true){ b.update(); networkSend(); repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } } public void networkSend(){ // Serialize to a byte array try { ByteArrayOutputStream bStream = new ByteArrayOutputStream(); ObjectOutputStream oo; oo = new ObjectOutputStream(bStream); oo.writeObject(b); oo.flush(); oo.close(); byte[] bufCar = bStream.toByteArray(); //socket = new DatagramSocket(); //socket.setSoTimeout(1000); InetAddress address = InetAddress.getByName("localhost"); DatagramPacket packet = new DatagramPacket(bufCar, bufCar.length, address, port); socket.send(packet); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

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• Generating triangles from a square grid

  - by vivi

  I have a 2D square grid of values representing terrain elevations, and I want to generate triangles from that grid to make a 3D view of the terrain. My first thought was to split each square diagonally into 2 triangles, however the split diagonal can clearly be seen, especially from the top : [Sorry, as a new user I can't post images, please see here : imgur] Is there a recommended way to generate triangles to remove/reduce this effect ?

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• Maya Animated Character export for XNA 4.0 problem

  - by FahidK

  To begin with, I'm trying to export an animated character in .fbx format from Maya 2013 to XNA 4.0 In Maya, The Model has a basic rig and the animations are in clips made in the Trax editor. so the issue i'm having is after selecting the model and the root joint and then hitting export in .fbx format, for some reason when i open the exported .fbx file the joint system is detached from the model with no animation. Btw, i have the animations in clips so that they can be called in code, for example "run","walk","attack". So, what can i do to solve this problem? Thank you.

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• Finding furthermost point in game world

  - by user13414

  I am attempting to find the furthermost point in my game world given the player's current location and a normalized direction vector in screen space. My current algorithm is: convert player world location to screen space multiply the direction vector by a large number (2000) and add it to the player's screen location to get the distant screen location convert the distant screen location to world space create a line running from the player's world location to the distant world location loop over the bounding "walls" (of which there are always 4) of my game world check whether the wall and the line intersect if so, where they intersect is the furthermost point of my game world in the direction of the vector Here it is, more or less, in code: public Vector2 GetFurthermostWorldPoint(Vector2 directionVector) { var screenLocation = entity.WorldPointToScreen(entity.Location); var distantScreenLocation = screenLocation + (directionVector * 2000); var distantWorldLocation = entity.ScreenPointToWorld(distantScreenLocation); var line = new Line(entity.Center, distantWorldLocation); float intersectionDistance; Vector2 intersectionPoint; foreach (var boundingWall in entity.Level.BoundingWalls) { if (boundingWall.Intersects(line, out intersectionDistance, out intersectionPoint)) { return intersectionPoint; } } Debug.Assert(false, "No intersection found!"); return Vector2.Zero; } Now this works, for some definition of "works". I've found that the further out my distant screen location is, the less chance it has of working. When digging into the reasons why, I noticed that calls to Viewport.Unproject could result in wildly varying return values for points that are "far away". I wrote this stupid little "test" to try and understand what was going on: [Fact] public void wtf() { var screenPositions = new Vector2[] { new Vector2(400, 240), new Vector2(400, -2000), }; var viewport = new Viewport(0, 0, 800, 480); var projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, viewport.Width / viewport.Height, 1, 200000); var viewMatrix = Matrix.CreateLookAt(new Vector3(400, 630, 600), new Vector3(400, 345, 0), new Vector3(0, 0, 1)); var worldMatrix = Matrix.Identity; foreach (var screenPosition in screenPositions) { var nearPoint = viewport.Unproject(new Vector3(screenPosition, 0), projectionMatrix, viewMatrix, worldMatrix); var farPoint = viewport.Unproject(new Vector3(screenPosition, 1), projectionMatrix, viewMatrix, worldMatrix); Console.WriteLine("For screen position {0}:", screenPosition); Console.WriteLine(" Projected Near Point = {0}", nearPoint.TruncateZ()); Console.WriteLine(" Projected Far Point = {0}", farPoint.TruncateZ()); Console.WriteLine(); } } The output I get on the console is: For screen position {X:400 Y:240}: Projected Near Point = {X:400 Y:629.571 Z:599.0967} Projected Far Point = {X:392.9302 Y:-83074.98 Z:-175627.9} For screen position {X:400 Y:-2000}: Projected Near Point = {X:400 Y:626.079 Z:600.7554} Projected Far Point = {X:390.2068 Y:-767438.6 Z:148564.2} My question is really twofold: what am I doing wrong with the unprojection such that it varies so wildly and, thus, does not allow me to determine the corresponding world point for my distant screen point? is there a better way altogether to determine the furthermost point in world space given a current world space location, and a directional vector in screen space?

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• Lighting with VBO

  - by nkint

  I'm using a Java JOGL wrapper called processing.org. I have coded some enviroment on it and I'm quite proud of it even if it has some ready stuffs that I didn't know anything about it (==LIGHTS). Then, for some geometry, I've decided to use a VBO. I had to pass in the hard way and recode all lights. But I can't achieve the same result. This is the original light system: And this with VBO: With this code: Vec3D l; gl.glEnable(GL.GL_LIGHTING); gl.glEnable(GL.GL_LIGHT0); gl.glEnable(GL.GL_COLOR_MATERIAL); gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_AMBIENT, new float[]{0.8f,0f,0f}, 0); l = new Vec3D(0,0,-10); gl.glColor3f(0.8f,0f,0f); gl.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, new float[] { l.x, l.y, l.z, 0 }, 0); gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPOT_DIRECTION, new float[] { 1, 1, 1, 1 }, 0); I can't achive the same light, the same color material, and the same wireframe stuffs. If needed I can also post the code I use for VBO, but it is quite standard vertex array grabbed on the net that uses glDrawArrays

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• Drawing a sprite or text causes the OpenGl rendering to 'disappear' in SFML

  - by Ken

  I'm using some SFML built in functions to draw sprites and text as an overlay on top of some OpenGL rending in an SFML RenderWindow. The opengl rendering appears fine until I add the code to draw the sprites or text. The sprite or text drawing causes the OpenGL stuff to disappear. The follow code show what I'm trying to do sf::RenderWindow window(sf::VideoMode(viewport.width,viewport.height,32), "SFML Window"); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0,viewport.width,0,viewport.height,0,1); while (window.pollEvent(Event)) { //event handling... //begin drawing glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBegin(GL_TRIANGLES); glColor3f(col.x,col.y,col.z); for(int i=0;i<3;i++) glVertex2f(pos.x+verts[i].x,pos.y+verts[i].y); glEnd(); // adding this line causes all the previous opengl triangles not to appear window.draw("Sometext"); window.display(); }

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• Building View Matrix in Direct3D11

  - by Balls

  Am I doing it right? I converted this. m_ViewMatrix = XMMatrixLookAtLH(XMLoadFloat3(&m_Position), lookAtVector, upVector); to this one. XMVECTOR vz = XMVector3Normalize( lookAtVector - XMLoadFloat3(&m_Position) ); XMVECTOR vx = XMVector3Normalize( XMVector3Cross( upVector, vz ) ); XMVECTOR vy = XMVector3Cross( vz, vx ); m_ViewMatrix.r[0] = vx; m_ViewMatrix.r[1] = vy; m_ViewMatrix.r[2] = vz; m_ViewMatrix.r[3] = XMLoadFloat3(&m_Position); m_ViewMatrix.r[0].m128_f32[3] = 0.0f; m_ViewMatrix.r[1].m128_f32[3] = 0.0f; m_ViewMatrix.r[2].m128_f32[3] = 0.0f; m_ViewMatrix.r[3].m128_f32[3] = 1.0f; m_ViewMatrix = XMMatrixInverse( &XMMatrixDeterminant(m_ViewMatrix), m_ViewMatrix ); Everything looks fine when I run it. Another question is, I saw on this site(http://webglfactory.blogspot.com/2011/06/how-to-create-view-matrix.html) that he subtracted lookat from position in his vector vz. I tried it but gave me wrong view matrix. Can anyone check my code. I'm studying linear algebra right now. Sucks my course doesn't have one. Thank you, Balls

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• Glitch-free cross-fades in HTML5

  - by Alexander Gladysh

  In my HTML5 canvas game, I need to cross-fade two sprites which have some glow around them. (Glow is backed into sprites.) Initially, the first sprite is visible. During the cross-fade the first sprite should vanish, and be replaced with the second one. How exactly the cross-fade is done — does not matter, as long as it is smooth and there are no visual glitches. I've tried two techniques: During the cross-fade I simultaneously interpolate alpha of the first sprite from 1.0 to 0.0, and alpha of the second sprite — from 0.0 to 1.0. With this technique I can see background in the middle of the cross-fade. That's because both sprites are semi-transparent most of the time. During the cross-fade I first interpolate alpha of the second sprite from 0.0 to 1.0 (first sprite alpha is at 1.0), and then interpolate alpha of the first sprite from 1.0 to 0.0. With this technique background is not seen, but the glow around sprites flashes during the cross-fide — when both sprites are near the full visibility. In non-HTML5 game I'd use shaders to do cross-fade separately in RGB and alpha channels. Is there a trick to do the cross-fade I need in HTML5 without visual glitches?

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• Kinect Click counter function

  - by Sweta Dwivedi

  So i have the following kinect click function which will check if the hand is within the bounds then it will click with a counter . . however there is a slight problem . .the first few button clicks work fine.. but after it clicks one of the buttons it changes the game state and immediately clicks the other button without the counter reaching 200. . . Kinect click is a method in the button class. . .and each button inside a list can access the Kinect click method. . . public bool KinectClick(int x,int y) { if ((x >= position.X && x <= position.X + position.Width) && (y >= position.Y && y <= position.Y + position.Height)) { counter++; if (counter > 200) { counter = 0; return true; } } else { counter = 0; } return false; } I call to check if this property is true in the Game update method to act as a button click. . foreach(Button g_t in Game_theme) { if ((g_t.KinectClick(x_c, y_c) == true || g_t.ButtonClicked() == true) && g_t.name == "animoe") { Selected_anim = true; currentGameState = GameState.InGame; } if ((g_t.KinectClick(x_c, y_c) == true || g_t.ButtonClicked() == true) && g_t.name == "planet") { Selected_planet = true; currentGameState = GameState.InGame; }

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• Show path of a body of where it should go after linear impulse is applied

  - by Farooq Arshed

  I am making a game with Andengine and Box2D. I have a dynamic body and I apply linear impulse on the body to move it around when the user have touched the screen. Now I want to show the path where the body will go when the user have touched. If you have played Angry Birds or Basket Ball Shoot or any other which have projectile motion with a path shown you will get my point. I want to show the white dots which are shown in those games.

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• Change collision action

  - by PatrickR

  I have a collision detection and its working fine, the problem is, that whenever my "bird" is hitting a "cloud", the cloud dissapers and i get some points. The same happens for the "sol" which it should, but not with the clouds. How can this be changed ? ive tryed a lot, but can seem to figger it out. Collision Code - (void)update:(ccTime)dt { bird.position = ccpAdd(bird.position, skyVelocity); NSMutableArray *projectilesToDelete = [[NSMutableArray alloc] init]; for (CCSprite *bird in _projectiles) { bird.anchorPoint = ccp(0, 0); CGRect absoluteBox = CGRectMake(bird.position.x, bird.position.y, [bird boundingBox].size.width, [bird boundingBox].size.height); NSMutableArray *targetsToDelete = [[NSMutableArray alloc] init]; for (CCSprite *cloudSprite in _targets) { cloudSprite.anchorPoint = ccp(0, 0); CGRect absoluteBox = CGRectMake(cloudSprite.position.x, cloudSprite.position.y, [cloudSprite boundingBox].size.width, [cloudSprite boundingBox].size.height); if (CGRectIntersectsRect([bird boundingBox], [cloudSprite boundingBox])) { [targetsToDelete addObject:cloudSprite]; } } for (CCSprite *solSprite in _targets) { solSprite.anchorPoint = ccp(0, 0); CGRect absoluteBox = CGRectMake(solSprite.position.x, solSprite.position.y, [solSprite boundingBox].size.width, [solSprite boundingBox].size.height); if (CGRectIntersectsRect([bird boundingBox], [solSprite boundingBox])) { [targetsToDelete addObject:solSprite]; score += 50/2; [scoreLabel setString:[NSString stringWithFormat:@"%d", score]]; } } // NÅR SKYEN BLIVER RAMT AF FUGLEN for (CCSprite *cloudSprite in targetsToDelete) { //[_targets removeObject:cloudSprite]; //[self removeChild:cloudSprite cleanup:YES]; } // NÅR SOLEN BLIVER RAMT AF FUGLEN for (CCSprite *solSprite in targetsToDelete) { [_targets removeObject:solSprite]; [self removeChild:solSprite cleanup:YES]; } if (targetsToDelete.count > 0) { [projectilesToDelete addObject:bird]; } [targetsToDelete release]; } // NÅR FUGLEN BLIVER RAMT AF ALT ANDET for (CCSprite *bird in projectilesToDelete) { //[_projectiles removeObject:bird]; //[self removeChild:bird cleanup:YES]; } [projectilesToDelete release]; }

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• Java: Reflection Packet Builder using getField()

  - by Matchlighter

  So I just finished writing a packet builder that dynamically loads data into a data stream which is then sent out. Each builder operates by finding fields in its class (and its superclasses) that are marked with an @data annotation. Upon finishing the builder, I remembered that getFields() does not return in "any specific order". I quite like my builder because it allows for quite simple, yet hard-typed packets. Could this implementation be a problem? What would be the best next step to keep the simplicity - do alphabetical sorting of fields?

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• GLSL: Strange light reflections

  - by Tom

  According to this tutorial I'm trying to make a normal mapping using GLSL, but something is wrong and I can't find the solution. The output render is in this image: Image1 in this image is a plane with two triangles and each of it is different illuminated (that is bad). The plane has 6 vertices. In the upper left side of this plane are 2 identical vertices (same in the lower right). Here are some vectors same for each vertice: normal vector = 0, 1, 0 (red lines on image) tangent vector = 0, 0,-1 (green lines on image) bitangent vector = -1, 0, 0 (blue lines on image) here I have one question: The two identical vertices does need to have the same tangent and bitangent? I have tried to make other values to the tangents but the effect was still similar. Here are my shaders Vertex shader: #version 130 // Input vertex data, different for all executions of this shader. in vec3 vertexPosition_modelspace; in vec2 vertexUV; in vec3 vertexNormal_modelspace; in vec3 vertexTangent_modelspace; in vec3 vertexBitangent_modelspace; // Output data ; will be interpolated for each fragment. out vec2 UV; out vec3 Position_worldspace; out vec3 EyeDirection_cameraspace; out vec3 LightDirection_cameraspace; out vec3 LightDirection_tangentspace; out vec3 EyeDirection_tangentspace; // Values that stay constant for the whole mesh. uniform mat4 MVP; uniform mat4 V; uniform mat4 M; uniform mat3 MV3x3; uniform vec3 LightPosition_worldspace; void main(){ // Output position of the vertex, in clip space : MVP * position gl_Position = MVP * vec4(vertexPosition_modelspace,1); // Position of the vertex, in worldspace : M * position Position_worldspace = (M * vec4(vertexPosition_modelspace,1)).xyz; // Vector that goes from the vertex to the camera, in camera space. // In camera space, the camera is at the origin (0,0,0). vec3 vertexPosition_cameraspace = ( V * M * vec4(vertexPosition_modelspace,1)).xyz; EyeDirection_cameraspace = vec3(0,0,0) - vertexPosition_cameraspace; // Vector that goes from the vertex to the light, in camera space. M is ommited because it's identity. vec3 LightPosition_cameraspace = ( V * vec4(LightPosition_worldspace,1)).xyz; LightDirection_cameraspace = LightPosition_cameraspace + EyeDirection_cameraspace; // UV of the vertex. No special space for this one. UV = vertexUV; // model to camera = ModelView vec3 vertexTangent_cameraspace = MV3x3 * vertexTangent_modelspace; vec3 vertexBitangent_cameraspace = MV3x3 * vertexBitangent_modelspace; vec3 vertexNormal_cameraspace = MV3x3 * vertexNormal_modelspace; mat3 TBN = transpose(mat3( vertexTangent_cameraspace, vertexBitangent_cameraspace, vertexNormal_cameraspace )); // You can use dot products instead of building this matrix and transposing it. See References for details. LightDirection_tangentspace = TBN * LightDirection_cameraspace; EyeDirection_tangentspace = TBN * EyeDirection_cameraspace; } Fragment shader: #version 130 // Interpolated values from the vertex shaders in vec2 UV; in vec3 Position_worldspace; in vec3 EyeDirection_cameraspace; in vec3 LightDirection_cameraspace; in vec3 LightDirection_tangentspace; in vec3 EyeDirection_tangentspace; // Ouput data out vec3 color; // Values that stay constant for the whole mesh. uniform sampler2D DiffuseTextureSampler; uniform sampler2D NormalTextureSampler; uniform sampler2D SpecularTextureSampler; uniform mat4 V; uniform mat4 M; uniform mat3 MV3x3; uniform vec3 LightPosition_worldspace; void main(){ // Light emission properties // You probably want to put them as uniforms vec3 LightColor = vec3(1,1,1); float LightPower = 40.0; // Material properties vec3 MaterialDiffuseColor = texture2D( DiffuseTextureSampler, vec2(UV.x,-UV.y) ).rgb; vec3 MaterialAmbientColor = vec3(0.1,0.1,0.1) * MaterialDiffuseColor; //vec3 MaterialSpecularColor = texture2D( SpecularTextureSampler, UV ).rgb * 0.3; vec3 MaterialSpecularColor = vec3(0.5,0.5,0.5); // Local normal, in tangent space. V tex coordinate is inverted because normal map is in TGA (not in DDS) for better quality vec3 TextureNormal_tangentspace = normalize(texture2D( NormalTextureSampler, vec2(UV.x,-UV.y) ).rgb*2.0 - 1.0); // Distance to the light float distance = length( LightPosition_worldspace - Position_worldspace ); // Normal of the computed fragment, in camera space vec3 n = TextureNormal_tangentspace; // Direction of the light (from the fragment to the light) vec3 l = normalize(LightDirection_tangentspace); // Cosine of the angle between the normal and the light direction, // clamped above 0 // - light is at the vertical of the triangle -> 1 // - light is perpendicular to the triangle -> 0 // - light is behind the triangle -> 0 float cosTheta = clamp( dot( n,l ), 0,1 ); // Eye vector (towards the camera) vec3 E = normalize(EyeDirection_tangentspace); // Direction in which the triangle reflects the light vec3 R = reflect(-l,n); // Cosine of the angle between the Eye vector and the Reflect vector, // clamped to 0 // - Looking into the reflection -> 1 // - Looking elsewhere -> < 1 float cosAlpha = clamp( dot( E,R ), 0,1 ); color = // Ambient : simulates indirect lighting MaterialAmbientColor + // Diffuse : "color" of the object MaterialDiffuseColor * LightColor * LightPower * cosTheta / (distance*distance) + // Specular : reflective highlight, like a mirror MaterialSpecularColor * LightColor * LightPower * pow(cosAlpha,5) / (distance*distance); //color.xyz = E; //color.xyz = LightDirection_tangentspace; //color.xyz = EyeDirection_tangentspace; } I have replaced the original color value by EyeDirection_tangentspace vector and then I got other strange effect but I can not link the image (not eunogh reputation) Is it possible that with this shaders is something wrong, or maybe in other place in my code e.g with my matrices? SOLVED Solved... 3 days needed for changing one letter from this: glBindBuffer(GL_ARRAY_BUFFER, vbo); glVertexAttribPointer ( 4, // attribute 3, // size GL_FLOAT, // type GL_FALSE, // normalized? sizeof(VboVertex), // stride (void*)(12*sizeof(float)) // array buffer offset ); to this: glBindBuffer(GL_ARRAY_BUFFER, vbo); glVertexAttribPointer ( 4, // attribute 3, // size GL_FLOAT, // type GL_FALSE, // normalized? sizeof(VboVertex), // stride (void*)(11*sizeof(float)) // array buffer offset ); see difference? :)

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• When I shoot from a gun while walking, the bullet is off the center, but when stand still it's fine

  - by Vlad1k

  I am making a small project in Unity, and whenever I walk with the gun and shoot at the same time, the bullets seem to curve and shoot off 2-3 CMs from the center. When I stand still this doesn't happen. This is my main Javascript code: @script RequireComponent(AudioSource) var projectile : Rigidbody; var speed = 500; var ammo = 30; var fireRate = 0.1; private var nextFire = 0.0; function Update() { if(Input.GetButton ("Fire1") && Time.time > nextFire) { if(ammo != 0) { nextFire = Time.time + fireRate; var clone = Instantiate(projectile, transform.position, transform.root.rotation); clone.velocity = transform.TransformDirection(Vector3 (0, 0, speed)); ammo = ammo - 1; audio.Play(); } else { } } } I assume that these two lines need to be tweaked: var clone = Instantiate(projectile, transform.position, transform.root.rotation); clone.velocity = transform.TransformDirection(Vector3 (0, 0, speed)); Thanks in advanced, and please remember that I just started Unity, and I might have a difficult time understanding some things. Thanks!

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• How do I keep a 3D model on the screen in OpenGL?

  - by NoobScratcher

  I'm trying to keep a 3D model on the screen by placing my glDrawElement functions inside the draw function with the declarations at the top of .cpp. When I render the model, the model attaches it self to the current vertex buffer object. This is because my whole graphical user interface is in 2D quads except the window frame. Is there a way to avoid this from happening? or any common causes of this? Creating the file object: int index = IndexAssigner(1, 1); //make a fileobject and store list and the index of that list in a c string ifstream file (list[index].c_str() ); //Make another string //string line; points.push_back(Point()); Point p; int face[4]; Model rendering code: int numfloats = 4; float* point=reinterpret_cast<float*>(&points[0]); int num_bytes=numfloats*sizeof(float); cout << "Size Of Point" << sizeof(Point) << endl; GLuint vertexbuffer; glGenVertexArrays(1, &vao[3]); glGenBuffers(1, &vertexbuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glBufferData(GL_ARRAY_BUFFER, points.size()*sizeof(points), points.data(), GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, num_bytes, &points[0]); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, points.size(), &points[0]); glEnableClientState(GL_INDEX_ARRAY); glIndexPointer(GL_FLOAT, faces.size(), faces.data()); glEnableVertexAttribArray(0); glDrawElements(GL_QUADS, points.size(), GL_UNSIGNED_INT, points.data()); glDrawElements(GL_QUADS, faces.size(), GL_UNSIGNED_INT, faces.data());

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• Architecture of an action multiplayer game from scratch

  - by lcf

  Not sure whether it's a good place to ask (do point me to a better one if it's not), but since what we're developing is a game - here it goes. So this is a "real-time" action multiplayer game. I have familiarized myself with concepts like lag compensation, view interpolation, input prediction and pretty much everything that I need for this. I have also prepared a set of prototypes to confirm that I understood everything correctly. My question is about the situation when game engine must be rewind to the past to find out whether there was a "hit" (sometimes it may involve the whole 'recomputation' of the world from that moment in the past up to the present moment. I already have a piece of code that does it, but it's not as neat as I need it to be. The domain logic of the app (the physics of the game) must be separated from the presentation (render) and infrastructure tools (e.g. the remote server interaction specifics). How do I organize all this? :) Is there any worthy implementation with open sources I can take a look at? What I'm thinking is something like this: -> Render / User Input -> Game Engine (this is the so called service layer) -> Processing User Commands & Remote Server -> Domain (Physics) How would you add into this scheme the concept of "ticks" or "interactions" with the possibility to rewind and recalculate "the game"? Remember, I cannot change the Domain/Physics but only the Game Engine. Should I store an array of "World's States"? Should they be just some representations of the world, optimized for this purpose somehow (how?) or should they be actual instances of the world (i.e. including behavior and all that). Has anybody had similar experience? (never worked on a game before if that matters)

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• std::vector::size with glDrawElements crashes?

  - by NoobScratcher

  ( win32 / OpenGL 3.3 / GLSL 330 ) I decided after a long time of trying to do a graphical user interface using just opengl graphics to go back to a gui toolkit and so in the process have had to port alot of my code to win32. But I have a problem with my glDrawElement function. my program compiles and runs fine until it gets to glDrawElements then crashes.. which is rather annoying right. so I was trying to figure out why and I found out its std::vector::size member not returning the correct amount of faces in the unsigned interger vector eg, "vector<unsigned int>faces; " so when I use cout << faces.size() << endl; I got 68 elements???? instead of 24 as you can see here in this .obj file: # Blender v2.61 (sub 0) OBJ File: '' # www.blender.org v 1.000000 -1.000000 -1.000000 v 1.000000 -1.000000 1.000000 v -1.000000 -1.000000 1.000000 v -1.000000 -1.000000 -1.000000 v 1.000000 1.000000 -0.999999 v 0.999999 1.000000 1.000001 v -1.000000 1.000000 1.000000 v -1.000000 1.000000 -1.000000 s off f 1 2 3 4 f 5 8 7 6 f 1 5 6 2 f 2 6 7 3 <--- 24 Faces not 68? f 3 7 8 4 f 5 1 4 8 I'm using a parser I created to get the faces/vertexes in my .obj file: char modelbuffer [20000]; int MAX_BUFF = 20000; unsigned int face[3]; FILE * pfile; pfile = fopen(szFileName, "rw"); while(fgets(modelbuffer, MAX_BUFF, pfile) != NULL) { if('v') { Point p; sscanf(modelbuffer, "v %f %f %f", &p.x, &p.y, &p.z); points.push_back(p); cout << " p.x = " << p.x << " p.y = " << p.y << " p.z = " << p.x << endl; } if('f') { sscanf(modelbuffer, "f %d %d %d %d", &face[0], &face[1], &face[2], &face[3]); cout << "face[0] = " << face[0] << " face[1] = " << face[1] << " face[2] = " << face[2] << " face[3] = " << face[3] << "\n"; faces.push_back(face[0] - 1); faces.push_back(face[1] - 1); faces.push_back(face[2] - 1); faces.push_back(face[3] - 1); cout << face[0] - 1 << face[1] - 1 << face[2] - 1 << face[3] - 1 << endl; } } using this struct to store the x,y,z positions also this vector was used with Point: vector<Point>points; struct Point { float x, y, z; }; If someone could tell me why its not working and how to fix it that would be awesome I also provide a pastebin to the full source code if you want a closer look. http://pastebin.com/gznYLVw7

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• HLSL problem with divide by homogeneous component

  - by Berend

  When I try to divide my position.z by my position.w in HLSL I get as result always 1.0f or higher. Is this a common problem for some reason? When I divide my position.x or y by the w this works fine. But the divide for the z gives a wrong result. I use the view matrix for my camera and the projection matrix as i use it in the game because I want to create a depthmap from the cameraposition. Can anybody explain what I'm doing wrong? Do I need another view matrix?

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• Incorrect results for frustum cull

  - by DeadMG

  Previously, I had a problem with my frustum culling producing too optimistic results- that is, including many objects that were not in the view volume. Now I have refactored that code and produced a cull that should be accurate to the actual frustum, instead of an axis-aligned box approximation. The problem is that now it never returns anything to be in the view volume. As the mathematical support library I'm using does not provide plane support functions, I had to code much of this functionality myself, and I'm not really the mathematical type, so it's likely that I've made some silly error somewhere. As follows is the relevant code: class Plane { public: Plane() { r0 = Math::Vector(0,0,0); normal = Math::Vector(0,1,0); } Plane(Math::Vector p1, Math::Vector p2, Math::Vector p3) { r0 = p1; normal = Math::Cross((p2 - p1), (p3 - p1)); } Math::Vector r0; Math::Vector normal; }; This class represents one plane as a point and a normal vector. class Frustum { public: Frustum( const std::array<Math::Vector, 8>& points ) { planes[0] = Plane(points[0], points[1], points[2]); planes[1] = Plane(points[4], points[5], points[6]); planes[2] = Plane(points[0], points[1], points[4]); planes[3] = Plane(points[2], points[3], points[6]); planes[4] = Plane(points[0], points[2], points[4]); planes[5] = Plane(points[1], points[3], points[5]); } Plane planes[6]; }; The points are passed in order where (the inverse of) each bit of the index of each point indicates whether it's the left, top, and back of the frustum, respectively. As such, I just picked any three points where they all shared one bit in common to define the planes. My intersection test is as follows (based on this): bool Intersects(Math::AABB lhs, const Frustum& rhs) const { for(int i = 0; i < 6; i++) { Math::Vector pvertex = lhs.TopRightFurthest; Math::Vector nvertex = lhs.BottomLeftClosest; if (rhs.planes[i].normal.x <= -0.0f) { std::swap(pvertex.x, nvertex.x); } if (rhs.planes[i].normal.y <= -0.0f) { std::swap(pvertex.y, nvertex.y); } if (rhs.planes[i].normal.z <= -0.0f) { std::swap(pvertex.z, nvertex.z); } if (Math::Dot(rhs.planes[i].r0, nvertex) < 0.0f) { return false; } } return true; } Also of note is that because I'm using a left-handed co-ordinate system, I wrote my Cross function to return the negative of the formula given on Wikipedia. Any suggestions as to where I've made a mistake?

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• Slerping rotation mirrors

  - by Esa

  I rotate my game character to watch at the target using the following code: transform.rotation = Quaternion.Slerp(startQuaternion, lookQuaternion, turningNormalizer*turningSpeed/10f) startQuaternion is the character's current rotation when a new target is given. lookQuaternion is the direction the character should look at and it's set like this: destinationVector = currentWaypoint.transform.position - transform.position; lookQuaternion = Quaternion.LookRotation(destinationVector, Vector3.up); turningNormalizer is just Time.deltaTime incremented and turningSpeed is a static value given in the editor. The problem is that while the character turns as it should most of the time, it has problems when it has to do close to 180 degrees. Then it at times jitters and mirrors the rotation: In this poorly drawn image the character(on the right) starts to turn towards the circle on the left. Instead of just turning either through left or right it starts this "mirror dance": It starts to rotate towards the new facing Then it suddenly snaps to the same angle but on other side and keeps rotating It does this "mirroring" so long until it looks at the target. Is this a thing with quaternions, slerping/lerping or something else?

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• Problems with SAT Collision Detection

  - by DJ AzKai

  I'm doing a project in one of my modules for college in C++ with SFML and I was hoping someone may be able to help me. I'm using a vector of squares and triangles and I am using the SAT collision detection method to see if objects collide and to make the objects respond to the collision appropriately using the MTV(minimum translation vector) Below is my code: //from the main method int main(){ // Create the main window sf::RenderWindow App(sf::VideoMode(800, 600, 32), "SFML OpenGL"); // Create a clock for measuring time elapsed sf::Clock Clock; srand(time(0)); //prepare OpenGL surface for HSR glClearDepth(1.f); glClearColor(0.3f, 0.3f, 0.3f, 0.f); //background colour glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); //// Setup a perspective projection & Camera position glMatrixMode(GL_PROJECTION); glLoadIdentity(); //set up a 3D Perspective View volume //gluPerspective(90.f, 1.f, 1.f, 300.0f);//fov, aspect, zNear, zFar //set up a orthographic projection same size as window //this mease the vertex coordinates are in pixel space glOrtho(0,800,0,600,0,1); // use pixel coordinates // Finally, display rendered frame on screen vector<BouncingThing*> triangles; for(int i = 0; i < 10; i++) { //instantiate each triangle; triangles.push_back(new BouncingTriangle(Vector2f(rand() % 700, rand() % 500), 3)); } vector<BouncingThing*> boxes; for(int i = 0; i < 10; i++) { //instantiate each box; boxes.push_back(new BouncingBox(Vector2f(rand() % 700, rand() % 500), 4)); } CollisionDetection * b = new CollisionDetection(); // Start game loop while (App.isOpen()) { // Process events sf::Event Event; while (App.pollEvent(Event)) { // Close window : exit if (Event.type == sf::Event::Closed) App.close(); // Escape key : exit if ((Event.type == sf::Event::KeyPressed) && (Event.key.code == sf::Keyboard::Escape)) App.close(); } //Prepare for drawing // Clear color and depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Apply some transformations glMatrixMode(GL_MODELVIEW); glLoadIdentity(); for(int i = 0; i < 10; i++) { triangles[i]->draw(); boxes[i]->draw(); triangles[i]->update(Vector2f(800,600)); boxes[i]->draw(); boxes[i]->update(Vector2f(800,600)); } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(boxes[i]))); } } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(boxes[i]))); } } App.display(); } return EXIT_SUCCESS; } (ignore this line) //from the BouncingThing.cpp BouncingThing::BouncingThing(Vector2f position, int noSides) : pos(position), pi(3.14), radius(3.14), nSides(noSides) { collided = false; if(nSides ==3) { Vector2f vert1 = Vector2f(-12.0f,-12.0f); Vector2f vert2 = Vector2f(0.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); } else if(nSides == 4) { Vector2f vert1 = Vector2f(-12.0f,12.0f); Vector2f vert2 = Vector2f(12.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); Vector2f vert4 = Vector2f(-12.0f, -12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); verts.push_back(vert4); } velocity.x = ((rand() % 5 + 1) / 3) + 1; velocity.y = ((rand() % 5 + 1) / 3 ) +1; } void BouncingThing::update(Vector2f screenSize) { Transform t; t.rotate(0); for(int i=0;i< verts.size(); i++) { verts[i]=t.transformPoint(verts[i]); } if(pos.x >= screenSize.x || pos.x <= 0) { velocity.x *= -1; } if(pos.y >= screenSize.y || pos.y <= 0) { velocity.y *= -1; } if(collided) { //velocity.x *= -1; //velocity.y *= -1; collided = false; } pos += velocity; } void BouncingThing::setCollision(bool x){ collided = x; } void BouncingThing::draw() { glBegin(GL_POLYGON); glColor3f(0,1,0); for(int i = 0; i < verts.size(); i++) { glVertex2f(pos.x + verts[i].x,pos.y + verts[i].y); } glEnd(); } vector<Vector2f> BouncingThing::getNormals() { vector<Vector2f> normalVerts; if(nSides == 3) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); Vector2f ac = Vector2f((verts[2].x + pos.x) - (verts[0].x + pos.x), (verts[2].y + pos.y) - (verts[0].y + pos.y)); ac = flip(ac); ac.x *= -1; normalVerts.push_back(ac); return normalVerts; } if(nSides ==4) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); return normalVerts; } } Vector2f BouncingThing::flip(Vector2f v){ float vyTemp = v.x; float vxTemp = v.y * -1; return Vector2f(vxTemp, vyTemp); } (Ignore this line) CollisionDetection::CollisionDetection() { } vector<float> CollisionDetection::bubbleSort(vector<float> w) { int temp; bool finished = false; while (!finished) { finished = true; for (int i = 0; i < w.size()-1; i++) { if (w[i] > w[i+1]) { temp = w[i]; w[i] = w[i+1]; w[i+1] = temp; finished=false; } } } return w; } class Vector{ public: //static int dp_count; static float dot(sf::Vector2f a,sf::Vector2f b){ //dp_count++; return a.x*b.x+a.y*b.y; } static float length(sf::Vector2f a){ return sqrt(a.x*a.x+a.y*a.y); } static Vector2f add(Vector2f a, Vector2f b) { return Vector2f(a.x + b.y, a.y + b.y); } static sf::Vector2f getNormal(sf::Vector2f a,sf::Vector2f b){ sf::Vector2f n; n=a-b; n/=Vector::length(n);//normalise float x=n.x; n.x=n.y; n.y=-x; return n; } }; bool CollisionDetection::CheckCollision(BouncingThing & x, BouncingThing & y) { vector<Vector2f> xVerts = x.getVerts(); vector<Vector2f> yVerts = y.getVerts(); vector<Vector2f> xNormals = x.getNormals(); vector<Vector2f> yNormals = y.getNormals(); int size; vector<float> xRange; vector<float> yRange; for(int j = 0; j < xNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(xNormals[j], Vector2f(xVerts[i].x, xVerts[i].x))); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(xNormals[j], Vector2f(yVerts[i].x , yVerts[i].y))); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } float x3 = Min(xRange[0], yRange[0]); float y3 = Max(xRange[xRange.size() - 1], yRange[yRange.size() - 1]); float length = Max(x3, y3) - Min(x3, y3); } for(int j = 0; j < yNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(yNormals[j], xVerts[i])); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(yNormals[j], yVerts[i])); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } } return true; } float CollisionDetection::Min(float min, float max) { if(max < min) { min = max; } else return min; } float CollisionDetection::Max(float min, float max) { if(min > max) { max = min; } else return min; } On the screen the objects will freeze for a small amount of time before moving off again. However the problem is is that when this happens there are no collisions actually happening and I would really love to find out where the flaw is in the code. If you need any more information/code please don't hesitate to ask and I'll reply as soon as possible Regards, AzKai

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