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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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  • 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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  • Java Animation Memory Overload [on hold]

    - by user2425429
    I need a way to reduce the memory usage of these programs while keeping the functionality. Every time I add 50 milliseconds or so to the set&display loop in AnimationTest1, it throws an out of memory error. Here is the code I have now: import java.awt.DisplayMode; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Polygon; import java.util.ArrayList; import java.util.List; import java.util.concurrent.Executor; import java.util.concurrent.Executors; import javax.swing.ImageIcon; public class AnimationTest1 { public static void main(String args[]) { AnimationTest1 test = new AnimationTest1(); test.run(); } private static final DisplayMode POSSIBLE_MODES[] = { new DisplayMode(800, 600, 32, 0), new DisplayMode(800, 600, 24, 0), new DisplayMode(800, 600, 16, 0), new DisplayMode(640, 480, 32, 0), new DisplayMode(640, 480, 24, 0), new DisplayMode(640, 480, 16, 0) }; private static final long DEMO_TIME = 4000; private ScreenManager screen; private Image bgImage; private Animation anim; public void loadImages() { // create animation List<Polygon> polygons=new ArrayList(); int[] x=new int[]{20,4,4,20,40,56,56,40}; int[] y=new int[]{20,32,40,44,44,40,32,20}; polygons.add(new Polygon(x,y,8)); anim = new Animation(); //# of frames long startTime = System.currentTimeMillis(); long currTimer = startTime; long elapsedTime = 0; boolean animated = false; Graphics2D g = screen.getGraphics(); int width=200; int height=200; //set&display loop while (currTimer - startTime < DEMO_TIME*2) { //draw the polygons if(!animated){ for(int j=0; j<polygons.size();j++){ for(int pos=0; pos<polygons.get(j).npoints; pos++){ polygons.get(j).xpoints[pos]+=1; } } anim.setNewPolyFrame(polygons , width , height , 64); } else{ // update animation anim.update(elapsedTime); draw(g); g.dispose(); screen.update(); try{ Thread.sleep(20); } catch(InterruptedException ie){} } if(currTimer - startTime == DEMO_TIME) animated=true; elapsedTime = System.currentTimeMillis() - currTimer; currTimer += elapsedTime; } } public void run() { screen = new ScreenManager(); try { DisplayMode displayMode = screen.findFirstCompatibleMode(POSSIBLE_MODES); screen.setFullScreen(displayMode); loadImages(); } finally { screen.restoreScreen(); } } public void draw(Graphics g) { // draw background g.drawImage(bgImage, 0, 0, null); // draw image g.drawImage(anim.getImage(), 0, 0, null); } } ScreenManager: import java.awt.Color; import java.awt.DisplayMode; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GraphicsConfiguration; import java.awt.GraphicsDevice; import java.awt.GraphicsEnvironment; import java.awt.Toolkit; import java.awt.Window; import java.awt.event.KeyListener; import java.awt.event.MouseListener; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; import javax.swing.JPanel; public class ScreenManager extends JPanel { private GraphicsDevice device; /** Creates a new ScreenManager object. */ public ScreenManager() { GraphicsEnvironment environment=GraphicsEnvironment.getLocalGraphicsEnvironment(); device = environment.getDefaultScreenDevice(); setBackground(Color.white); } /** Returns a list of compatible display modes for the default device on the system. */ public DisplayMode[] getCompatibleDisplayModes() { return device.getDisplayModes(); } /** Returns the first compatible mode in a list of modes. Returns null if no modes are compatible. */ public DisplayMode findFirstCompatibleMode( DisplayMode modes[]) { DisplayMode goodModes[] = device.getDisplayModes(); for (int i = 0; i < modes.length; i++) { for (int j = 0; j < goodModes.length; j++) { if (displayModesMatch(modes[i], goodModes[j])) { return modes[i]; } } } return null; } /** Returns the current display mode. */ public DisplayMode getCurrentDisplayMode() { return device.getDisplayMode(); } /** Determines if two display modes "match". Two display modes match if they have the same resolution, bit depth, and refresh rate. The bit depth is ignored if one of the modes has a bit depth of DisplayMode.BIT_DEPTH_MULTI. Likewise, the refresh rate is ignored if one of the modes has a refresh rate of DisplayMode.REFRESH_RATE_UNKNOWN. */ public boolean displayModesMatch(DisplayMode mode1, DisplayMode mode2) { if (mode1.getWidth() != mode2.getWidth() || mode1.getHeight() != mode2.getHeight()) { return false; } if (mode1.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && mode2.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && mode1.getBitDepth() != mode2.getBitDepth()) { return false; } if (mode1.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && mode2.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && mode1.getRefreshRate() != mode2.getRefreshRate()) { return false; } return true; } /** Enters full screen mode and changes the display mode. If the specified display mode is null or not compatible with this device, or if the display mode cannot be changed on this system, the current display mode is used. <p> The display uses a BufferStrategy with 2 buffers. */ public void setFullScreen(DisplayMode displayMode) { JFrame frame = new JFrame(); frame.setUndecorated(true); frame.setIgnoreRepaint(true); frame.setResizable(true); device.setFullScreenWindow(frame); if (displayMode != null && device.isDisplayChangeSupported()) { try { device.setDisplayMode(displayMode); } catch (IllegalArgumentException ex) { } } frame.createBufferStrategy(2); Graphics g=frame.getGraphics(); g.setColor(Color.white); g.drawRect(0, 0, frame.WIDTH, frame.HEIGHT); frame.paintAll(g); g.setColor(Color.black); g.dispose(); } /** Gets the graphics context for the display. The ScreenManager uses double buffering, so applications must call update() to show any graphics drawn. <p> The application must dispose of the graphics object. */ public Graphics2D getGraphics() { Window window = device.getFullScreenWindow(); if (window != null) { BufferStrategy strategy = window.getBufferStrategy(); return (Graphics2D)strategy.getDrawGraphics(); } else { return null; } } /** Updates the display. */ public void update() { Window window = device.getFullScreenWindow(); if (window != null) { BufferStrategy strategy = window.getBufferStrategy(); if (!strategy.contentsLost()) { strategy.show(); } } // Sync the display on some systems. // (on Linux, this fixes event queue problems) Toolkit.getDefaultToolkit().sync(); } /** Returns the window currently used in full screen mode. Returns null if the device is not in full screen mode. */ public Window getFullScreenWindow() { return device.getFullScreenWindow(); } /** Returns the width of the window currently used in full screen mode. Returns 0 if the device is not in full screen mode. */ public int getWidth() { Window window = device.getFullScreenWindow(); if (window != null) { return window.getWidth(); } else { return 0; } } /** Returns the height of the window currently used in full screen mode. Returns 0 if the device is not in full screen mode. */ public int getHeight() { Window window = device.getFullScreenWindow(); if (window != null) { return window.getHeight(); } else { return 0; } } /** Restores the screen's display mode. */ public void restoreScreen() { Window window = device.getFullScreenWindow(); if (window != null) { window.dispose(); } device.setFullScreenWindow(null); } /** Creates an image compatible with the current display. */ public BufferedImage createCompatibleImage(int w, int h, int transparency) { Window window = device.getFullScreenWindow(); if (window != null) { GraphicsConfiguration gc = window.getGraphicsConfiguration(); return gc.createCompatibleImage(w, h, transparency); } return null; } } Animation: import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Polygon; import java.awt.image.BufferedImage; import java.util.ArrayList; import java.util.List; /** The Animation class manages a series of images (frames) and the amount of time to display each frame. */ public class Animation { private ArrayList frames; private int currFrameIndex; private long animTime; private long totalDuration; /** Creates a new, empty Animation. */ public Animation() { frames = new ArrayList(); totalDuration = 0; start(); } /** Adds an image to the animation with the specified duration (time to display the image). */ public synchronized void addFrame(BufferedImage image, long duration){ ScreenManager s = new ScreenManager(); totalDuration += duration; frames.add(new AnimFrame(image, totalDuration)); } /** Starts the animation over from the beginning. */ public synchronized void start() { animTime = 0; currFrameIndex = 0; } /** Updates the animation's current image (frame), if necessary. */ public synchronized void update(long elapsedTime) { if (frames.size() >= 1) { animTime += elapsedTime; /*if (animTime >= totalDuration) { animTime = animTime % totalDuration; currFrameIndex = 0; }*/ while (animTime > getFrame(0).endTime) { frames.remove(0); } } } /** Gets the Animation's current image. Returns null if this animation has no images. */ public synchronized Image getImage() { if (frames.size() > 0&&!(currFrameIndex>=frames.size())) { return getFrame(currFrameIndex).image; } else{ System.out.println("There are no frames!"); System.exit(0); } return null; } private AnimFrame getFrame(int i) { return (AnimFrame)frames.get(i); } private class AnimFrame { Image image; long endTime; public AnimFrame(Image image, long endTime) { this.image = image; this.endTime = endTime; } } public void setNewPolyFrame(List<Polygon> polys,int imagewidth,int imageheight,int time){ BufferedImage image=new BufferedImage(imagewidth, imageheight, 1); Graphics g=image.getGraphics(); for(int i=0;i<polys.size();i++){ g.drawPolygon(polys.get(i)); } addFrame(image,time); g.dispose(); } }

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  • XNA model drawing problem

    - by user1990950
    When using this code: public static void DrawModel(Model model, Vector3 position, Vector3 offset, float xRotation, float yRotation, float zRotation, float allrot, float xScale, float yScale, float zScale) { position.Y *= -1; offset.Y *= -1; Matrix worldMatrix = ((Matrix.CreateRotationZ(MathHelper.ToRadians(zRotation)) * Matrix.CreateRotationX(MathHelper.ToRadians(xRotation))) * Matrix.CreateRotationY(MathHelper.ToRadians(yRotation))) * (Matrix.CreateTranslation(offset) * Matrix.CreateRotationY(MathHelper.ToRadians(allrot))) * Matrix.CreateScale(xScale, yScale, zScale); worldMatrix *= Matrix.CreateTranslation(position) * theCamera.GetTransformation() * Matrix.CreateTranslation(new Vector3(-(graphics.GraphicsDevice.Viewport.Width / 2), graphics.GraphicsDevice.Viewport.Height / 2, 0)); foreach (ModelMesh mesh in model.Meshes) { for (int i = 0; i < mesh.Effects.Count; i++) { ((BasicEffect)mesh.Effects[i]).EnableDefaultLighting(); ((BasicEffect)mesh.Effects[i]).World = worldMatrix; ((BasicEffect)mesh.Effects[i]).View = viewMatrix; ((BasicEffect)mesh.Effects[i]).Projection = projectionMatrix; } mesh.Draw(); } } The model rotates and then scales. It should scale and then rotate, but whenever I try to change it, it won't work.

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  • Implementing movement on a grid

    - by Dvole
    I have a simple snake game, where I have other NPC snakes on the field. How do I calculate the movement of those other snakes so that they did not hit walls, and each other? So far I have it like this: I check for current coordinates and when there is a wall nearby I change direction to some other one. And so on, this way the snakes never collide the walls. But not actually colliding other snakes, how do I prevent this? I figured I could probe for the direction I'm heading and if there is anything there I would change direction too, but there is a set of situation where this won't work, for example if another snake will block off all exits later.

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  • scaling point sprites with distance

    - by Will
    How can you scale a point sprite by its distance from the camera? GLSL fragment shader: gl_PointSize = size / gl_Position.w; seems along the right tracks; for any given scene all sprites seem nicely scaled by distance. Is this correct? How do you compute the proper scaling for my vertex attribute size? I want each sprite to be scaled by the modelview matrix. I had played with arbitrary values and it seems that size is the radius in pixels at the camera, and is not in modelview scale. I've also tried: gl_Position = pMatrix * mvMatrix * vec4(vertex,1.0); vec4 v2 = pMatrix * mvMatrix * vec4(vertex.x,vertex.y+0.5*size,vertex.z,1.0); gl_PointSize = length(gl_Position.xyz-v2.xyz) * gl_Position.w; But this makes the sprites be bigger in the distance, rather than smaller:

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  • Circle collision detection and Vector math: HELP?

    - by Griffin
    Hey so i'm currently going through the wildbunny blog to learn about collision detection, but i'm a bit confused on how the vectors he's talking about come into play QUOTED BLOG: p = ||A-B|| – (r1+r2) The two spheres are penetrating by distance p. We would also like the penetration vector so that we can correct the penetration once we discover it. This is the vector that moves both circles to the point where they just touch, correcting the penetration. Importantly it is not only just a vector that does this, it is the only vector which corrects the penetration by moving the minimum amount. This is important because we only want to correct the error, not introduce more by moving too much when we correct, or too little. N = (A-B) / ||A-B|| P = N*p Here we have calculated the normalised vector N between the two centres and the penetration vector P by multiplying our unit direction by the penetration distance. Ok so i understand that p is the distance each circle is penetrating each other, but i don't get what exactly N and P is. it seems to me N is just the coordinates of the 3rd point of the right trianlge formed by point A and B (A-B) then being divided by the hypotenuse of that triangle or distance between A and B (||A-B||) Whats the significance of this? Also, what is the penetration vector used for? It seems to me like a movement that one of the circles would perform to get un-penetrated.

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  • How do I simulate the mouse and keyboard using C# or C++?

    - by Art
    I want to start develop for Kinect, but hardest theme for it - how to send keyboard and mouse input to any application. In previous question I got an advice to develop my own driver for this devices, but this will take a while. I imagine application like a gate, that can translate SendMessage's into system wide input or driver application with API to send this inputs. So I wonder, is there are drivers or simulators that can interact with C# or C++? Small edition: SendMessage, PostMessage, keybd_event will work only on Windows application with common messages loop. So I need driver application that will work on low, kernel, level.

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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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  • 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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  • Procedural object generation and unique identification

    - by 2080
    My question relates to procedural content generation and data management of the emerging objects in a database. I assume a networked game, with a server-client model. Unspecified objects in the game world are generated while the game is running with procedural algorithms (for example perlin noise). The players (/clients) can modify the properties of these objects, but have to notify the server of these changes. How could this communication address unique objects, so that both the server and the client know of which object they are speaking? Not only the inner properties of the objects can differ, but also visible, such as the position. When the player wants to select one of these objects the game has to find out the id - does anyone know which methods or algorithms can accomplish that?

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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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  • Jumping a sprite while moving in a Bezier action

    - by marcg11
    I'm creating a game and I need the sprite to jump (move up and down basically) while it's moving on a bezier path so it moves vertically while it still follows the path. If I do this while it's moving along the bezier path: [mySprite runAction:[CCJumpBy actionWithDuration:0.1 position:ccp(0,0) height:10 jumps:1]]; It jumps vertically but instantly it returns to the position on the path. What I want is to jump relative to the path. Anyone knows something about it? It would looks something like this: the curve is a sequence of CCBezierBy's by the way. Thanks.

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  • Developing games using virtualization on macOS (or Linux) [on hold]

    - by zpinner
    From what I've seen, most of the gamedev tools and engines (that could generate cross platform games) are not supported on Mac. Havok/Project Anarchy, UDK, GameMaker, e.g. . Basically, the only options I found are: Unity3d and monogame + xamarin. Unity is nice and I've been playing with it for some time, but the free version is quite limited when we're talking about shaders, that made me consider that as an indie developer, I might want more freedom to experiment new things, without paying the expensive unity license. I didn't try monogame + xamarin yet, and altough XNA is a very nice game framework, I'd like to have more freedom to experiment and finish a game first before paying for the IDE, which is not possible with the current Xamarin business model. That leaves me with the thought that I must go back to windows, which I'd preferably do it partially, if it's possible. Using BootCamp is something that I'd like to avoid, since it's a pain to reboot when changing OS and that would probably force me to become a 100% windows user. Is there anyone actually developing a game using virtualization solutions like parallels or vmwareFusion? How was your experience?

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  • Good GUI for OpenGL

    - by Cristina
    I am starting to learn OpenGL with FreeGLUT using the Superbible and the knowledge i have from my elementary graphics to brush up on my skills. To get more from this experience i want to integrate a GUI to overwrite the one FreeGLUT uses, now my question is this: is this thing possible and what library should i use? Some characteristics for the library: Open source Multi-platform (Linux and Windows) C/C++ If you have any other recommendations please feel free to post them along with your answers for my problem.

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  • Is there a cross-platform special directory I can use for game save files?

    - by Suds
    I'm developing with LWJGL and Java on a Windows 7 laptop. I've successfully set up saving to the %appdata%\gamename\saves\ or long form c:\users\user\appdata\roaming\gamename\saves\ folder by using File dir = new File(System.getenv("APPDATA") + "\\gamename\\saves\\");. I have hobbyist level experience with Linux, and zero experience with OSX. My game will be fully cross platform. Is System.getenv("APPDATA"); cross platform? If so, where does it point to on Linux or OSX? Is there a best practices alternative that I should use?

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  • Avoid double compression of resources

    - by user1095108
    I am using .pngs for my textures and am using a virtual file system in a .zip file for my game project. This means my textures are compressed and decompressed twice. What are the solutions to this double compression problem? One solution I've heard about is to use .tgas for textures, but it seems ages ago, since I've heard that. Another solution is to implement decompression on the GPU and, since that is fast, forget about the overhead.

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  • how to make a continuous machine gun sound-effect

    - by Jan
    I am trying to make an entity fire one or more machine-guns. For each gun I store the time between shots (1.0 / firing rate) and the time since the last shot. Also I've loaded ~10 different gun-shot sound-effects. Now, for each gun I do the following: function update(deltatime): timeSinceLastShot += deltatime if timeSinceLastShot >= timeBetweenShots + verySmallRandomValue(): timeSinceLastShot -= timeBetweenShots if gunIsFiring: displayMuzzleFlash() spawnBullet() selectRandomSound().play() But now I often get a crackling noise (which I assume is when two or more guns are firing at the same time and confuse the sound-device). My question is whether A) This a common problem and there is a well-known solution, maybe to do with the channels or something, or B) I am using a completely wrong approach to the task. I had a look at some sound-assets for other games and they used complete burst with multiple shots. I suppose I could try that, but I would like to have organic little hickups in the gun-fire (that's what the random value is for) to make the game more gritty and dirty. I am using Panda3D, but I had the exact same problem in PyGame and SDL. [edit] Thanks a lot for the answers so far! One more problem with faking it though: Now how do I stop the sound? Let's say I have an effect with 5 bangs... *bang* *bang* *bang* *bang* *bang* And I magically manage to loop it so that there's no gap or overlap if the player fires more than 5 shots. Now, what do I do if the player stops firing halfway through the third bang? How do I know how long to keep playing the sample so that the third bang is completed and I can start playing the rumbling echo of the last shot? Of course I can look up the shot/pause timing of that sound-sample and code accordingly, but it feels extremely hacky.

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  • My frustum culling is culling from the wrong point [SOLVED]

    - by Xbetas
    I'm having problems with my frustum being in the wrong origin. It follows the rotation of my camera but not the position. In my camera class I'm generating a view-matrix: void Camera::Update() { UpdateViewMatrix(); glMatrixMode(GL_MODELVIEW); //glLoadIdentity(); glLoadMatrixf(GetViewMatrix().m); } Then extracting the planes using the projection matrix and modelview matrix: void UpdateFrustum() { Matrix4x4 projection, model, clip; glGetFloatv(GL_PROJECTION_MATRIX, projection.m); glGetFloatv(GL_MODELVIEW_MATRIX, model.m); clip = model * projection; m_Planes[RIGHT][0] = clip.m[ 3] - clip.m[ 0]; m_Planes[RIGHT][1] = clip.m[ 7] - clip.m[ 4]; m_Planes[RIGHT][2] = clip.m[11] - clip.m[ 8]; m_Planes[RIGHT][3] = clip.m[15] - clip.m[12]; NormalizePlane(RIGHT); m_Planes[LEFT][0] = clip.m[ 3] + clip.m[ 0]; m_Planes[LEFT][1] = clip.m[ 7] + clip.m[ 4]; m_Planes[LEFT][2] = clip.m[11] + clip.m[ 8]; m_Planes[LEFT][3] = clip.m[15] + clip.m[12]; NormalizePlane(LEFT); m_Planes[BOTTOM][0] = clip.m[ 3] + clip.m[ 1]; m_Planes[BOTTOM][1] = clip.m[ 7] + clip.m[ 5]; m_Planes[BOTTOM][2] = clip.m[11] + clip.m[ 9]; m_Planes[BOTTOM][3] = clip.m[15] + clip.m[13]; NormalizePlane(BOTTOM); m_Planes[TOP][0] = clip.m[ 3] - clip.m[ 1]; m_Planes[TOP][1] = clip.m[ 7] - clip.m[ 5]; m_Planes[TOP][2] = clip.m[11] - clip.m[ 9]; m_Planes[TOP][3] = clip.m[15] - clip.m[13]; NormalizePlane(TOP); m_Planes[NEAR][0] = clip.m[ 3] + clip.m[ 2]; m_Planes[NEAR][1] = clip.m[ 7] + clip.m[ 6]; m_Planes[NEAR][2] = clip.m[11] + clip.m[10]; m_Planes[NEAR][3] = clip.m[15] + clip.m[14]; NormalizePlane(NEAR); m_Planes[FAR][0] = clip.m[ 3] - clip.m[ 2]; m_Planes[FAR][1] = clip.m[ 7] - clip.m[ 6]; m_Planes[FAR][2] = clip.m[11] - clip.m[10]; m_Planes[FAR][3] = clip.m[15] - clip.m[14]; NormalizePlane(FAR); } void NormalizePlane(int side) { float length = 1.0/(float)sqrt(m_Planes[side][0] * m_Planes[side][0] + m_Planes[side][1] * m_Planes[side][1] + m_Planes[side][2] * m_Planes[side][2]); m_Planes[side][0] *= length; m_Planes[side][1] *= length; m_Planes[side][2] *= length; m_Planes[side][3] *= length; } And check against it with: bool PointInFrustum(float x, float y, float z) { for(int i = 0; i < 6; i++) { if( m_Planes[i][0] * x + m_Planes[i][1] * y + m_Planes[i][2] * z + m_Planes[i][3] <= 0 ) return false; } return true; } Then i render using: camera->Update(); UpdateFrustum(); int numCulled = 0; for(int i = 0; i < (int)meshes.size(); i++) { if(!PointInFrustum(meshCenter.x, meshCenter.y, meshCenter.z)) { meshes[i]->SetDraw(false); numCulled++; } else meshes[i]->SetDraw(true); } Matrices look like (Camera is at (5, 0, 0)): ModelView [0,0,0.99,0] [0,1,0,0] [-0.99,0,0,0] [0,0,-5,1] Projection [0.814,0,0,0] [0,1.303,0,0] [0,0,-1,0] [0,0,-0.02,0] Clip [0,0,-1,-0.999] [0,1.30,0,0] [-0.814,0,0,0] [0,0,4.98,4.99] What am i doing wrong?

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  • Where to implement storable items

    - by James Hay
    I'm creating a multiplayer online trading game. The things that are traded range from raw items to complex products. For example Steel is a raw item. Mechanical Assembly is a more complex item that requires 2x Steel and maybe 1x Rubber. Then Hydraulics is an item that contains 2x Mechanical Assemblies and 1x Electronics (which is another complex item). So and so forth. These items will be created by me, players can't create their own items, so it doesn't need to be able to handle arbitrary layers of complexity for items. If my example isn't clear, think Minecraft. You have wooden planks, which can be made into sticks. From there the sticks - combined with metals - can be made into tools. My game is nothing to do with minecraft or any sandbox building game, but it uses a similar progressive complexity to creating items that I want to have in my game. My question is basically, how do you store something like this assuming that I will want to add more items in the future? Do you store it in a database or in a seperate library that the game uses? EDIT None of the items actually "do" anything, they are simply there to either sell, purchase, or combine with other items to make a more complex item, which can then be sold, purchased or combined... you get the idea. The items themselves would not have any properties, but the instances of the items would. For example an item that one player has would have a certain "quality" and if they were selling it a certain "price". An instance of that same item that a different player had would need to have a different "quality" and "price" if they were selling it. I think the price part will not be required on an individual item because instead I would have a "sale" object which was for a price and contained certain items.

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  • Realtime rendering using a ray tracing engine

    - by Keyhan Asghari
    I want to render an object that has a mesh with one million hexagonal elements(100 * 100 * 100). Lights, shadows and textures is not important and each element has a solid color. and finally, the actions I want to have, is simply rotating the object, zooming and panning. I am wondering what ray tracing engine is better for my conditions. or, do I have to take another approach? any help will be appreciated.

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  • Check for bodies within a specific circle in Box2D

    - by ltjax
    I'm trying to find positions to insert new bodies into my world. For that, I'd like to have a "free" spot where this body wouldn't overlap with anything else. So my plan was to sample "random" positions and check whether they overlap with my "potential" new body. Since my bodies are always circular, I'd need to test within a given circle. So far, the only way to use box2d for this seems to use b2World::QueryAABB around my circle and manually doing an overlap test with all the fixtures it gives me (Box2D doesn't event seem to allow me to tap into its overlapping tests?!). It seems to me like Box2D should already provide such functionality - is there a way that lets me do this without reinventing most of the wheel again?

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  • Calculate velocity of a bullet ricocheting on a circle

    - by SteveL
    I made a picture to demostrate what I need,basecaly I have a bullet with velocity and I want it to bounce with the correct angle after it hits a circle Solved(look the accepted answer for explain): Vector.vector.set(bullet.vel); //->v Vector.vector2.setDirection(pos, bullet.pos); //->n normal from center of circle to bullet float dot=Vector.vector.dot(Vector.vector2); //->dot product Vector.vector2.mul(dot).mul(2); Vector.vector.sub(Vector.vector2); Vector.vector.y=-Vector.vector.y; //->for some reason i had to invert the y bullet.vel.set(Vector.vector);

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  • OpenGL ES 2 jittery camera movement

    - by user16547
    First of all, I am aware that there's no camera in OpenGL (ES 2), but from my understanding proper manipulation of the projection matrix can simulate the concept of a camera. What I'm trying to do is make my camera follow my character. My game is 2D, btw. I think the principle is the following (take Super Mario Bros or Doodle Jump as reference - actually I'm trying to replicate the mechanics of the latter): when the caracter goes beyond the center of the screen (in the positive axis/direction), update the camera to be centred on the character. Else keep the camera still. I did accomplish that, however the camera movement is noticeably jittery and I ran out of ideas how to make it smoother. First of all, my game loop (following this article): private int TICKS_PER_SECOND = 30; private int SKIP_TICKS = 1000 / TICKS_PER_SECOND; private int MAX_FRAMESKIP = 5; @Override public void run() { loops = 0; if(firstLoop) { nextGameTick = SystemClock.elapsedRealtime(); firstLoop = false; } while(SystemClock.elapsedRealtime() > nextGameTick && loops < MAX_FRAMESKIP) { step(); nextGameTick += SKIP_TICKS; loops++; } interpolation = ( SystemClock.elapsedRealtime() + SKIP_TICKS - nextGameTick ) / (float)SKIP_TICKS; draw(); } And the following code deals with moving the camera. I was unsure whether to place it in step() or draw(), but it doesn't make a difference to my problem at the moment, as I tried both and neither seemed to fix it. center just represents the y coordinate of the centre of the screen at any time. Initially it is 0. The camera object is my own custom "camera" which basically is a class that just manipulates the view and projection matrices. if(character.getVerticalSpeed() >= 0) { //only update camera if going up float[] projectionMatrix = camera.getProjectionMatrix(); if( character.getY() > center) { center += character.getVerticalSpeed(); cameraBottom = center + camera.getBottom(); cameraTop = center + camera.getTop(); Matrix.orthoM(projectionMatrix, 0, camera.getLeft(), camera.getRight(), center + camera.getBottom(), center + camera.getTop(), camera.getNear(), camera.getFar()); } } Any thought about what I should try or what I am doing wrong? Update 1: I think I updated every value you can see on screen to check whether the jittery movement is affected by that, but nothing changed, so something must be fundamentally flawed with my approach/calculations.

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  • 2D SAT Collision Detection not working when using certain polygons (With example)

    - by sFuller
    My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug? Edit: I forgot this function, which gives me the interval distance: float Polygon::GetIntervalDistance(float minA, float maxA, float minB, float maxB) { float intervalDistance; if (minA < minB) { intervalDistance = minB - maxA; } else { intervalDistance = minA - maxB; } return intervalDistance; //A positive value indicates this axis can be separated. } Edit 2: I have recreated the problem in HTML5/Javascript: Demo

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