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  • How do I have an arrow follow different height parabolas depending on how long the player holds down a key?

    - by Moondustt
    i'm trying to throw an arrow in my game, but i'm having a hard time trying to realize how to make a good parabola. What I need: The more you hold "enter" stronger the arrow goes. The arrow angle will be always the same, 45 degrees. This is what I have already have: private float velocityHeld = 1f; protected override void Update(GameTime gameTime) { private void GetKeyboardEvent() { if (Keyboard.GetState().IsKeyDown(Keys.Enter) && !released) { timeHeld += velocityHeld; holding = true; } else { if (holding) { released = true; holding = false; lastTimeHeld = timeHeld; } } } if (released && timeHeld > 0) { float alpha = MathHelper.ToRadians(45f); double vy = timeHeld * Math.Sin(alpha); double vx = timeHeld * Math.Cos(alpha); ShadowPosition.Y -= (int)vy; ShadowPosition.X += (int)vx; timeHeld -= velocityHeld; } else { released = false; } } My question is, what do I need to do to make the arrow to go bottom as it loses velocity (timeHeld) to make a perfect parabola?

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  • PyOpenGL: glVertexPointer() offset problem

    - by SurvivalMachine
    My vertices are interleaved in a numpy array (dtype = float32) like this: ... tu, tv, nx, ny, nz, vx, vy, vz, ... When rendering, I'm calling gl*Pointer() like this (I have enabled the arrays before): stride = (2 + 3 + 3) * 4 glTexCoordPointer( 2, GL_FLOAT, stride, self.vertArray ) glNormalPointer( GL_FLOAT, stride, self.vertArray + 2 ) glVertexPointer( 3, GL_FLOAT, stride, self.vertArray + 5 ) glDrawElements( GL_TRIANGLES, len( self.indices ), GL_UNSIGNED_SHORT, self.indices ) The result is that nothing renders. However, if I organize my array so that the vertex position is the first element ( ... vx, vy, vz, tu, tv, nx, ny, nz, ... ) I get correct positions for vertices while rendering but texture coords and normals aren't rendered correctly. This leads me to believe that I'm not setting the pointer offset right. How should I set it? I'm using almost the exact same code in my other app in C++ and it works.

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  • Mass Ball-to-Ball Collision Handling (as in, lots of balls)

    - by BlueThen
    Update: Found out that I was using the radius as the diameter, which was why the mtd was overcompensating. Hi, StackOverflow. I've written a Processing program awhile back simulating ball physics. Basically, I have a large number of balls (1000), with gravity turned on. Detection works great, but my issue is that they start acting weird when they're bouncing against other balls in all directions. I'm pretty confident this involves the handling. For the most part, I'm using Jay Conrod's code. One part that's different is if (distance > 1.0) return; which I've changed to if (distance < 1.0) return; because the collision wasn't even being performed with the first bit of code, I'm guessing that's a typo. The balls overlap when I use his code, which isn't what I was looking for. My attempt to fix it was to move the balls to the edge of each other: float angle = atan2(y - collider.y, x - collider.x); float distance = dist(x,y, balls[ID2].x,balls[ID2].y); x = collider.x + radius * cos(angle); y = collider.y + radius * sin(angle); This isn't correct, I'm pretty sure of that. I tried the correction algorithm in the previous ball-to-ball topic: // get the mtd Vector2d delta = (position.subtract(ball.position)); float d = delta.getLength(); // minimum translation distance to push balls apart after intersecting Vector2d mtd = delta.multiply(((getRadius() + ball.getRadius())-d)/d); // resolve intersection -- // inverse mass quantities float im1 = 1 / getMass(); float im2 = 1 / ball.getMass(); // push-pull them apart based off their mass position = position.add(mtd.multiply(im1 / (im1 + im2))); ball.position = ball.position.subtract(mtd.multiply(im2 / (im1 + im2))); except my version doesn't use vectors, and every ball's weight is 1. The resulting code I get is this: PVector delta = new PVector(collider.x - x, collider.y - y); float d = delta.mag(); PVector mtd = new PVector(delta.x * ((radius + collider.radius - d) / d), delta.y * ((radius + collider.radius - d) / d)); // push-pull apart based on mass x -= mtd.x * 0.5; y -= mtd.y * 0.5; collider.x += mtd.x * 0.5; collider.y += mtd.y * 0.5; This code seems to over-correct collisions. Which doesn't make sense to me because in no other way do I modify the x and y values of each ball, other than this. Some other part of my code could be wrong, but I don't know. Here's the snippet of the entire ball-to-ball collision handling I'm using: if (alreadyCollided.contains(new Integer(ID2))) // if the ball has already collided with this, then we don't need to reperform the collision algorithm return; Ball collider = (Ball) objects.get(ID2); PVector collision = new PVector(x - collider.x, y - collider.y); float distance = collision.mag(); if (distance == 0) { collision = new PVector(1,0); distance = 1; } if (distance < 1) return; PVector velocity = new PVector(vx,vy); PVector velocity2 = new PVector(collider.vx, collider.vy); collision.div(distance); // normalize the distance float aci = velocity.dot(collision); float bci = velocity2.dot(collision); float acf = bci; float bcf = aci; vx += (acf - aci) * collision.x; vy += (acf - aci) * collision.y; collider.vx += (bcf - bci) * collision.x; collider.vy += (bcf - bci) * collision.y; alreadyCollided.add(new Integer(ID2)); collider.alreadyCollided.add(new Integer(ID)); PVector delta = new PVector(collider.x - x, collider.y - y); float d = delta.mag(); PVector mtd = new PVector(delta.x * ((radius + collider.radius - d) / d), delta.y * ((radius + collider.radius - d) / d)); // push-pull apart based on mass x -= mtd.x * 0.2; y -= mtd.y * 0.2; collider.x += mtd.x * 0.2; collider.y += mtd.y * 0.2; Thanks. (Apologies for lack of sources, stackoverflow thinks I'm a spammer)

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  • slowly rotate an object towards another object

    - by numerical25
    I have an object that points in the direction of another object (i.e. it rotates to the direction that the second objects x and y coordinates are at) below is the code I use. var distx = target.x - x; var disty = target.y - y; var angle:Number = Math.atan2(disty, distx); var vx:Number = Math.cos(angle) * cspeed; var vy:Number = Math.sin(angle) * cspeed; rotation = angle * 180/Math.PI; x += vx; y += vy; as you can see. Not only does it rotate towards the target object, but it also moves towards it too. When I play the movie, the object instantly points to the targeted object and moves towards it. I would like for it to slowly turn towards the object instead of instantly turning towards it. anyone know how to do this.

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  • Gamepad Control for Processing + Android to Control Arduino Robot

    - by Iker
    I would like to create a Multitouch Gamepad control for Processing and use it to control a remote Arduino Robot. I would like to make the GUI on Processing and compile it for Android. Here is the GUI Gamepad for Processing I have created so far: float easing = 0.09; // start position int posX = 50; int posY = 200; // target position int targetX = 50; int targetY = 200; boolean dragging = false; void setup() { size(500,250); smooth(); } void draw() { background(255); if (!dragging) { // calculate the difference in position, apply easing and add to vx/vy float vx = (targetX - (posX)) * easing; float vy = (targetY - (posY)) * easing; // Add the velocity to the current position: make it move! posX += vx; posY += vy; } if(mousePressed) { dragging = true; posX = mouseX; posY = mouseY; } else { dragging = false; } DrawGamepad(); DrawButtons(); } void DrawGamepad() { //fill(0,155,155); //rect(0, 150, 100, 100, 15); ellipseMode(RADIUS); // Set ellipseMode to RADIUS fill(0,155,155); // Set fill to blue ellipse(50, 200, 50, 50); // Draw white ellipse using RADIUS mode ellipseMode(CENTER); // Set ellipseMode to CENTER fill(255); // Set fill to white// ellipse(posX, posY, 35, 35); // Draw gray ellipse using CENTER mode } void DrawButtons() { fill(0,155,155); // Set fill to blue ellipse(425, 225, 35, 35); ellipse(475, 225, 35, 35); fill(255,0,0); // Set fill to blue ellipse(425, 175, 35, 35); ellipse(475, 175, 35, 35); } I have realized that probably that code will not support Multitouch events on Android so I came up with another code found on this link Can Processing handle multi-touch? So the aim of this project is to create de multitouch gamepad to use to control my Arduino Robot. The gamepad should detect which key was pressed as well as the direction of the Joystick. Any help appreciated.

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  • O'Reilly book clarification on 2d linear system

    - by Eric
    The Oreilly book "Learning openCV" states at page 356 : Quote Before we get totally lost, let’s consider a particular realistic situation of taking measurements on a car driving in a parking lot. We might imagine that the state of the car could be summarized by two position variables, x and y, and two velocities, vx and vy. These four variables would be the elements of the state vector xk. Th is suggests that the correct form for F is: x = [ x; y; vx; vy; ]k F = [ 1, 0, dt, 0; 0, 1, 0, dt; 0, 0, 1, 0; 0, 0, 0, 1; ] It seems natural to put 'dt' just there in the F matrix but I just don't get why. What if I have a n states system, how would I spray some "dt" in the F matrix?

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  • Bouncing a ball off a surface

    - by Sagekilla
    Hi all, I'm currently in the middle of writing a game like Breakout, and I was wondering how I could properly bounce a ball off a surface. I went with the naive way of rotating the velocity by 180 degrees, which was: [vx, vy] -> [-vy, vx] Which (unsurprisingly) didn't work so well. If I know the position and veocity of the ball, as well as the point the ball would hit (but is going to instead bounce off of) how can I bounce it off that point? I don't need any language specific code. If anyone could provide a small, mathematical formula on how to properly do this that would work fine for me. I also need this to work with integer positions and velocity (I can't use floating point anywhere). Thanks!

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  • Call a non member function on an instance before is constructed.

    - by Tom
    Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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  • Call a non member funcion on an instance before is constructed.

    - by Tom
    Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); ~C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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  • How do I use a graphics method to pass parameters? Example is below.

    - by sonny5
    private static void getCorners(out float Wx, out float Wy, out float Vx, out float Vy) { // note-- I don't know how to flip the Y axis using this method... this is not a "graphics" method // In other words, I should use something like: // flipY(object sender, System.EventArgs e); // but don't know the syntax or whatever // I tried to do this: //Graphics g = this.CreateGraphic //Matrix myMatrix2 = new Matrix(1, 0, 0, -1, 0, 0); // flip Y axis //g.Transform = myMatrix2; //g.TranslateTransform(0, 480, MatrixOrder.Append); // ...but I get the error: // error CS0026: Keyword 'this' is not valid in a static property, static method, or // static field initializer Wx = 1.00F; Wy = 1.00F; // make this 1.00 (not 3.00F) down from the TOP since cannot get Y flipped Vx = ((Wx- WXmin)*((VXmax-VXmin)+VXmin)/(WXmax-WXmin)); Vy = ((Wy-WYmin)*(VYmax-VYmin)/(WYmax-WYmin)+VYmin); } thanks, Sonny5

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  • trouble running smooth animation in thread only when using key listener

    - by heysuse renard
    first time using a forum for coding help so sorry if i post this all wrong. i have more than a few classes i don't think screenManger or core holds the problem but i included them just incase. i got most of this code working through a set of tutorials. but a certain point started trying to do more on my own. i want to play the animation only when i'm moving my sprite. in my KeyTest class i am using threads to run the animation it used to work (poorly) but now not at all pluss it really gunks up my computer. i think it's because of the thread. im new to threads so i'm not to sure if i should even be using one in this situation or if its dangerous for my computer. the animation worked smoothly when i had the sprite bouce around the screen forever. the animation loop played with out stopping. i think the main problem is between the animationThread, Sprite, and keyTest classes, but itcould be more indepth. if someone could point me in the right direction for making the animation run smoothly when i push down a key and stop runing when i let off it would be greatly apriciated. i already looked at this Java a moving animation (sprite) obviously we were doing the same tutorial. but i feel my problem is slightly different. p.s. sorry for the typos. import java.awt.*; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import java.util.ArrayList; import javax.swing.ImageIcon; import javax.swing.JFrame; public class KeyTest extends Core implements KeyListener { public static void main(String[] args) { new KeyTest().run(); } Sprite player1; Image hobo; Image background; animation hoboRun; animationThread t1; //init also calls init form superclass public void init() { super.init(); loadImages(); Window w = s.getFullScreenWindow(); w.setFocusTraversalKeysEnabled(false); w.addKeyListener(this); } //load method will go here. //load all pics need for animation and sprite public void loadImages() { background = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\yellow square.jpg").getImage(); Image face1 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\circle.png").getImage(); Image face2 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\one eye.png").getImage(); hoboRun = new animation(); hoboRun.addScene(face1, 250); hoboRun.addScene(face2, 250); player1 = new Sprite(hoboRun); this.t1 = new animationThread(); this.t1.setAnimation(player1); } //key pressed public void keyPressed(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_ESCAPE) { stop(); } if (keyCode == KeyEvent.VK_RIGHT) { player1.setVelocityX(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_UP) { player1.setVelocityY(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1);; th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } else { e.consume(); } } //keyReleased @SuppressWarnings("static-access") public void keyReleased(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_RIGHT || keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } if (keyCode == KeyEvent.VK_UP || keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } else { e.consume(); } } //last method from interface public void keyTyped(KeyEvent e) { e.consume(); } //draw public void draw(Graphics2D g) { Window w = s.getFullScreenWindow(); g.setColor(w.getBackground()); g.fillRect(0, 0, s.getWidth(), s.getHieght()); g.setColor(w.getForeground()); g.drawImage(player1.getImage(), Math.round(player1.getX()), Math.round(player1.getY()), null); } public void update(long timePassed) { player1.update(timePassed); } } abstract class Core { private static DisplayMode modes[] = { new DisplayMode(1600, 900, 64, 0), new DisplayMode(800, 600, 32, 0), new DisplayMode(800, 600, 24, 0), new DisplayMode(800, 600, 16, 0), new DisplayMode(800, 480, 32, 0), new DisplayMode(800, 480, 24, 0), new DisplayMode(800, 480, 16, 0),}; private boolean running; protected ScreenManager s; //stop method public void stop() { running = false; } public void run() { try { init(); gameLoop(); } finally { s.restoreScreen(); } } //set to full screen //set current background here public void init() { s = new ScreenManager(); DisplayMode dm = s.findFirstCompatibleMode(modes); s.setFullScreen(dm); Window w = s.getFullScreenWindow(); w.setFont(new Font("Arial", Font.PLAIN, 20)); w.setBackground(Color.GREEN); w.setForeground(Color.WHITE); running = true; } //main gameLoop public void gameLoop() { long startTime = System.currentTimeMillis(); long cumTime = startTime; while (running) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; update(timePassed); Graphics2D g = s.getGraphics(); draw(g); g.dispose(); s.update(); try { Thread.sleep(20); } catch (Exception ex) { } } } //update animation public void update(long timePassed) { } //draws to screen abstract void draw(Graphics2D g); } class animationThread implements Runnable { String name; boolean playing; Sprite a; //constructor takes input from keyboard public animationThread() { } //The run method for animation public void run() { long startTime = System.currentTimeMillis(); long cumTime = startTime; boolean test = getRunning(); while (test) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; test = getRunning(); } } public String getName() { return name; } public void setAnimation(Sprite a) { this.a = a; } public void setName(String name) { this.name = name; } public void setRunning(boolean running) { this.playing = running; } public boolean getRunning() { return playing; } } class animation { private ArrayList scenes; private int sceneIndex; private long movieTime; private long totalTime; //constructor public animation() { scenes = new ArrayList(); totalTime = 0; start(); } //add scene to ArrayLisy and set time for each scene public synchronized void addScene(Image i, long t) { totalTime += t; scenes.add(new OneScene(i, totalTime)); } public synchronized void start() { movieTime = 0; sceneIndex = 0; } //change scenes public synchronized void update(long timePassed) { if (scenes.size() > 1) { movieTime += timePassed; if (movieTime >= totalTime) { movieTime = 0; sceneIndex = 0; } while (movieTime > getScene(sceneIndex).endTime) { sceneIndex++; } } } //get animations current scene(aka image) public synchronized Image getImage() { if (scenes.size() == 0) { return null; } else { return getScene(sceneIndex).pic; } } //get scene private OneScene getScene(int x) { return (OneScene) scenes.get(x); } //Private Inner CLASS////////////// private class OneScene { Image pic; long endTime; public OneScene(Image pic, long endTime) { this.pic = pic; this.endTime = endTime; } } } class Sprite { private animation a; private float x; private float y; private float vx; private float vy; //Constructor public Sprite(animation a) { this.a = a; } //change position public void update(long timePassed) { x += vx * timePassed; y += vy * timePassed; } public void startAnimation(long timePassed) { a.update(timePassed); } //get x position public float getX() { return x; } //get y position public float getY() { return y; } //set x public void setX(float x) { this.x = x; } //set y public void setY(float y) { this.y = y; } //get sprite width public int getWidth() { return a.getImage().getWidth(null); } //get sprite height public int getHeight() { return a.getImage().getHeight(null); } //get horizontal velocity public float getVelocityX() { return vx; } //get vertical velocity public float getVelocityY() { return vx; } //set horizontal velocity public void setVelocityX(float vx) { this.vx = vx; } //set vertical velocity public void setVelocityY(float vy) { this.vy = vy; } //get sprite / image public Image getImage() { return a.getImage(); } } class ScreenManager { private GraphicsDevice vc; public ScreenManager() { GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment(); vc = e.getDefaultScreenDevice(); } //get all compatible DM public DisplayMode[] getCompatibleDisplayModes() { return vc.getDisplayModes(); } //compares DM passed into vc DM and see if they match public DisplayMode findFirstCompatibleMode(DisplayMode modes[]) { DisplayMode goodModes[] = vc.getDisplayModes(); for (int x = 0; x < modes.length; x++) { for (int y = 0; y < goodModes.length; y++) { if (displayModesMatch(modes[x], goodModes[y])) { return modes[x]; } } } return null; } //get current DM public DisplayMode getCurrentDisplayMode() { return vc.getDisplayMode(); } //checks if two modes match each other public boolean displayModesMatch(DisplayMode m1, DisplayMode m2) { if (m1.getWidth() != m2.getWidth() || m1.getHeight() != m2.getHeight()) { return false; } if (m1.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m2.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m1.getBitDepth() != m2.getBitDepth()) { return false; } if (m1.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m2.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m1.getRefreshRate() != m2.getRefreshRate()) { return false; } return true; } //make frame full screen public void setFullScreen(DisplayMode dm) { JFrame f = new JFrame(); f.setUndecorated(true); f.setIgnoreRepaint(true); f.setResizable(false); vc.setFullScreenWindow(f); if (dm != null && vc.isDisplayChangeSupported()) { try { vc.setDisplayMode(dm); } catch (Exception ex) { } } f.createBufferStrategy(2); } //sets graphics object = this return public Graphics2D getGraphics() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); return (Graphics2D) s.getDrawGraphics(); } else { return null; } } //updates display public void update() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); if (!s.contentsLost()) { s.show(); } } } //returns full screen window public Window getFullScreenWindow() { return vc.getFullScreenWindow(); } //get width of window public int getWidth() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getWidth(); } else { return 0; } } //get height of window public int getHieght() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getHeight(); } else { return 0; } } //get out of full screen public void restoreScreen() { Window w = vc.getFullScreenWindow(); if (w != null) { w.dispose(); } vc.setFullScreenWindow(null); } //create image compatible with monitor public BufferedImage createCopatibleImage(int w, int h, int t) { Window win = vc.getFullScreenWindow(); if (win != null) { GraphicsConfiguration gc = win.getGraphicsConfiguration(); return gc.createCompatibleImage(w, h, t); } return null; } }

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  • 2D Tile based Game Collision problem

    - by iNbdy
    I've been trying to program a tile based game, and I'm stuck at the collision detection. Here is my code (not the best ^^): void checkTile(Character *c, int **map) { int x1,x2,y1,y2; /* Character position in the map */ c->upY = (c->y) / TILE_SIZE; // Top left corner c->downY = (c->y + c->h) / TILE_SIZE; // Bottom left corner c->leftX = (c->x) / TILE_SIZE; // Top right corner c->rightX = (c->x + c->w) / TILE_SIZE; // Bottom right corner x1 = (c->x + 10) / TILE_SIZE; // 10px from left side point x2 = (c->x + c->w - 10) / TILE_SIZE; // 10px from right side point y1 = (c->y + 10) / TILE_SIZE; // 10px from top side point y2 = (c->y + c->h - 10) / TILE_SIZE; // 10px from bottom side point /* Top */ if (map[c->upY][x1] > 2 || map[c->upY][x2] > 2) c->topCollision = 1; else c->topCollision = 0; /* Bottom */ if ((map[c->downY][x1] > 2 || map[c->downY][x2] > 2)) c->downCollision = 1; else c->downCollision = 0; /* Left */ if (map[y1][c->leftX] > 2 || map[y2][c->leftX] > 2) c->leftCollision = 1; else c->leftCollision = 0; /* Right */ if (map[y1][c->rightX] > 2 || map[y2][c->rightX] > 2) c->rightCollision = 1; else c->rightCollision = 0; } That calculates 8 collision points My moving function is like that: void movePlayer(Character *c, int **map) { if ((c->dirX == LEFT && !c->leftCollision) || (c->dirX == RIGHT && !c->rightCollision)) c->x += c->vx; if ((c->dirY == UP && !c->topCollision) || (c->dirY == DOWN && !c->downCollision)) c->y += c->vy; checkPosition(c, map); } and the checkPosition: void checkPosition(Character *c, int **map) { checkTile(c, map); if (c->downCollision) { if (c->state != JUMPING) { c->vy = 0; c->y = (c->downY * TILE_SIZE - c->h); } } if (c->leftCollision) { c->vx = 0; c->x = (c->leftX) * TILE_SIZE + TILE_SIZE; } if (c->rightCollision) { c->vx = 0; c->x = c->rightX * TILE_SIZE - c->w; } } This works, but sometimes, when the player is landing on ground, right and left collision points become equal to 1. So it's as if there were collision coming from left or right. Does anyone know why this is doing this?

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  • Speed, delta time and movement

    - by munchor
    player.vx = scroll_speed * dt /* Update positions */ player.x += player.vx player.y += player.vy I have a delta time in miliseconds, and I was wondering how I can use it properly. I tried the above, but that makes the player go fast when the computer is fast, and the player go slow when the computer is slow. The same thing happens with jumping. The player can jump really high when the computer is faster. This is sort of unfair, I think, because. Should I be doing this someway else? Thanks.

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  • Bouncing ball slowing down over time

    - by user46610
    I use the unreal engine 4 to bounce a ball off of walls in a 2D space, but over time the ball gets slower and slower. Movement happens in the tick function of the ball FVector location = GetActorLocation(); location.X += this->Velocity.X * DeltaSeconds; location.Y += this->Velocity.Y * DeltaSeconds; SetActorLocation(location, true); When a wall gets hit I get a Hit Event with the normal of the collision. This is how I calculate the new velocity of the ball: FVector2D V = this->Velocity; FVector2D N = FVector2D(HitNormal.X, HitNormal.Y); FVector2D newVelocity = -2 * (V.X * N.X + V.Y * N.Y) * N + V; this->Velocity = newVelocity; Over time, the more the ball bounced around, the velocity gets smaller and smaller. How do I prevent speed loss when bouncing off walls like that? It's supposed to be a perfect bounce without friction or anything.

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  • Parse SyndicationItem to c# class

    - by user285677
    What's the best way to parse the folowing rss Syndication Item into a c# class: <rss version="2.0" xmlns:fh="http://rss.flightstats.com/ns/rss/1.0"> <channel> <title>FlightStats - Lisboa Airport Departures</title> <language>en-us</language> <copyright>Copyright (c) 2007 Conducive Technology Inc. All rights reserved.</copyright> <description>FlightStats is your source for airport and flight information</description> <link>http://www.flightstats.com?utm_source=49e3481552e7c4c9:4e080df5:1281bf8969d:60e0&utm_medium=cpc&utm_campaign=rss</link> <pubDate>Sun, 25 Apr 2010 12:30:14 +0000</pubDate> <lastBuildDate>Sun, 25 Apr 2010 12:30:14 +0000</lastBuildDate> <ttl>15</ttl> <image> <url>http://dem5xqcn61lj8.cloudfront.net/Widgets/images/flightstats_logo_widget.gif</url> <title>FlightStats - Lisboa Airport Departures</title> <link>http://www.flightstats.com?utm_source=49e3481552e7c4c9:4e080df5:1281bf8969d:60e0&utm_medium=cpc&utm_campaign=rss</link> </image> <item> <fh:FlightHistory FlightHistoryId="190011545" DepartureDate="2010-04-25 12:00" ArrivalDate="2010-04-25 14:45" PublishedDepartureDate="2010-04-25 12:00" PublishedArrivalDate="2010-04-25 14:45" ScheduledGateDepartureDate="2010-04-25 12:00" ScheduledGateArrivalDate="2010-04-25 14:45" EstimatedGateArrivalDate="2010-04-25 14:40" ActualRunwayDepartureDate="2010-04-25 12:13" FlightNumber="8461" StatusCode="A" Status="Active" CreatorCode="O" ScheduledBlockTime="105" DepartureAirportTimeZoneOffset="1" ArrivalAirportTimeZoneOffset="2" ScheduledAircraftType="320" DepartureTerminal="T1" ArrivalTerminal="1" TrackingEnabled="False"> <fh:Airline AirlineCode="VY" Name="Vueling Airlines" /> <fh:Origin AirportCode="LIS" Name="Lisboa Airport" City="Lisbon" CountryCode="PT" /> <fh:Destination AirportCode="BCN" Name="Barcelona Airport" City="Barcelona" StateCode="SP" CountryCode="ES" /> </fh:FlightHistory> <guid isPermaLink="false">VY8461LISBCN</guid> <title>VY 8461 LIS-BCN Departed</title> <description> teste </description> <link>http://www.flightstats.com/go/FlightStatus/flightStatusByFlight.do? id=190011545&utm_source=49e3481552e7c4c9:4e080df5:1281bf8969d:60e0&utm_medium=cpc&utm_campaign=rss</link> </item> </channel> </rss>

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  • 2d trajectory planning of a spaceship with physics.

    - by egarcia
    I'm implementing a 2D game with ships in space. In order to do it, I'm using LÖVE, which wraps Box2D with Lua. But I believe that my question can be answered by anyone with a greater understanding of physics than myself - so pseudo code is accepted as a response. My problem is that I don't know how to move my spaceships properly on a 2D physics-enabled world. More concretely: A ship of mass m is located at an initial position {x, y}. It has an initial velocity vector of {vx, vy} (can be {0,0}). The objective is a point in {xo,yo}. The ship has to reach the objective having a velocity of {vxo, vyo} (or near it), following the shortest trajectory. There's a function called update(dt) that is called frequently (i.e. 30 times per second). On this function, the ship can modify its position and trajectory, by applying "impulses" to itself. The magnitude of the impulses is binary: you can either apply it in a given direction, or not to apply it at all). In code, it looks like this: def Ship:update(dt) m = self:getMass() x,y = self:getPosition() vx,vy = self.getLinearVelocity() xo,yo = self:getTargetPosition() vxo,vyo = self:getTargetVelocity() thrust = self:getThrust() if(???) angle = ??? self:applyImpulse(math.sin(angle)*thrust, math.cos(angle)*thrust)) end end The first ??? is there to indicate that in some occasions (I guess) it would be better to "not to impulse" and leave the ship "drift". The second ??? part consists on how to calculate the impulse angle on a given dt. We are in space, so we can ignore things like air friction. Although it would be very nice, I'm not looking for someone to code this for me; I put the code there so my problem is clearly understood. What I need is an strategy - a way of attacking this. I know some basic physics, but I'm no expert. For example, does this problem have a name? That sort of thing. Thanks a lot.

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  • Dynamic Jump spot

    - by Pasquale Sada
    I have an initial velocity V(Vx,Vy,VZ) and a spot where he stands still at S(Sx,Sy,Sz). What I'm trying to achieve is a jump on a spot E(Ex,Ey,Ez) where you have clicked on(only lower or higher spot, because I've in place a simple steering behavior for even terrains). There are no obstacle around. I've implemented a formula that can make him jump in a precise way on a spot but you need to declare an angle: the problem arise when the selected spot is straight above your head. It' pretty lame that the char hang there and can reach a thing that is 1cm above is head. I'll share the code I'm using: Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 *a)); return vel * dir.normalized;

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  • Theory of computation - Using the pumping lemma for context free languages

    - by Tony
    I'm reviewing my notes for my course on theory of computation and I'm having trouble understanding how to complete a certain proof. Here is the question: A = {0^n 1^m 0^n | n>=1, m>=1} Prove that A is not regular. It's pretty obvious that the pumping lemma has to be used for this. So, we have |vy| = 1 |vxy| <= p (p being the pumping length, = 1) uv^ixy^iz exists in A for all i = 0 Trying to think of the correct string to choose seems a bit iffy for this. I was thinking 0^p 1^q 0^p, but I don't know if I can obscurely make a q, and since there is no bound on u, this could make things unruly.. So, how would one go about this?

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  • Theory of computation - Using the pumping lemma for CFLs

    - by Tony
    I'm reviewing my notes for my course on theory of computation and I'm having trouble understanding how to complete a certain proof. Here is the question: A = {0^n 1^m 0^n | n>=1, m>=1} Prove that A is not regular. It's pretty obvious that the pumping lemma has to be used for this. So, we have |vy| = 1 |vxy| <= p (p being the pumping length, = 1) uv^ixy^iz exists in A for all i = 0 Trying to think of the correct string to choose seems a bit iffy for this. I was thinking 0^p 1^q 0^p, but I don't know if I can obscurely make a q, and since there is no bound on u, this could make things unruly.. So, how would one go about this?

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  • Virtual bridged networking with VLAN, could not ping

    - by v.yegy
    I require a virtual network with VLAN be build between two virtual hosts - which can be (lxc/ vbox -ubuntu or win xp). I tried with lxc and vbox with Ubuntu and was finding difficult to make it work without vlan, but was successful with vbox with xp. vbox-xp1 --- br1 ---------------- br2 ---- vbox-xp2 The config is: brctl addbr br1; brctl addbr br2 ifconfig br1 up; ifconfig br2 up stp br1 off; stp br2 off ip link add name br1-br2-l0 type veth peer name br1-br2-l1 sudo brctl addif br1 br1-br2-l0 sudo brctl addif br2 br1-br2-l1 vbox - xp 1 and 2 with network ; bridged and br1 and br2 respectively. The adapter is intel PRO/1000 MT Server and driver installed in guests. Configured IPs and two hosts pinged! VLAN config: ip link add link br1 name br1-2.5 type vlan id 5 brctl addif br2 br1-2.5 create vlan 5 in xp 1 and 2 and assign ip address Ping on with this config does not work. Wireshark trace on interface br1-br2-l1 / br1-2.5 shows that one ping results in ~240 ping packets and each growing by 4 bytes - first one being correct and 60, ping does not reach other host as I see mac is not learnt[arp -a]. -- if br1-2.5 is not configured, I see untagged packets in br1-br2-l1/0, but still not reaching other host as mac is not learnt. if br1-br2-l0/1 is made down, even if br1-2.5 is up, I count not see any packets. I tried with ebtables, but still could not make a correct config to work. -- If any one here are aware of any configuration, please let me know. I need to make a network of switches. Seems I have a very long way. Sorry for a very long question. Thanks and regards, vy

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  • Making AI jump on a spot effectively

    - by Pasquale Sada
    How to calculate, in 3D environment, the closest point, from which an AI character can jump onto a platform? Setup I have an initial velocity V(Vx,Vy,VZ) and a spot where the character stands still at S(Sx,Sy,Sz). What I'm trying to achieve is a successful jump on a spot E(Ex,Ey,Ez) where you have clicked on(only lower or higher spot, because I've in place a simple steering behavior for even terrains). There are no obstacles around. I've implemented a formula that can make him jump in a precise way on a spot but you need to declare an angle: the problem arise when the selected spot is straight above your head. It' pretty lame that the char hang there and can reach a thing that is 1cm above is head. I'll share the code I'm using: Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 *a)); return vel * dir.normalized; Ended up using the lowest angle (20 degree) and checking for collision on the trajectory. If found any increase the angle. Here some code (to improve the code maybe must stop the check at the highest point of the curve): Vector3 BallisticVel(Vector3 target, float angle) { Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 * a)); return vel * dir.normalized; } Vector3 TrajectoryPoint(Vector3 startingPosition, Vector3 startingVelocity, float n ) { float t = 1/60 ; // seconds per time step Vector3 stepVelocity = t * startingVelocity; // m/s Vector3 stepGravity = t * t * Physics.gravity; // m/s/s return startingPosition + n * stepVelocity + 0.5f * (n*n+n) * stepGravity; } bool CheckTrajectory(Vector3 startingPosition,Vector3 target, float angle_jump) { Debug.Log("checking"); if(angle_jump < 80f) { Debug.Log("if"); Vector3 startingVelocity = BallisticVel(target, angle_jump); for (int i = 0; i < 180; i++) { //Debug.Log(i); Vector3 trajectoryPosition = TrajectoryPoint( startingPosition, startingVelocity, i ); if(Physics.Raycast(trajectoryPosition,Vector3.forward,safeDistance)) { angle_jump += 10; break; // restart loop with the new angle } else continue; } return true; JumpVelocity = BallisticVel(target, angle_jump); } return false; }

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  • flexible length struct array inside another struct using C

    - by renz
    Hi I am trying to use C to implement a simple struct: 2 boxes, each contains different number of particles; the exact number of particles are passed in main(). I wrote the following code: typedef struct Particle{ float x; float y; float vx; float vy; }Particle; typedef struct Box{ Particle p[]; }Box; void make_box(Box *box, int number_of_particles); int main(){ Box b1, b2; make_box(&b1, 5); //create a box containing 5 particles make_box(&b2, 10); //create a box containing 10 particles } I've tried to implement make_box with the following code void make_box(struct Box *box, int no_of_particles){ Particle po[no_of_particles]; po[0].x = 1; po[1].x = 2; //so on and so forth... box->p = po; } It's always giving me "invalid use of flexible array member". Greatly appreciated if someone can shed some light on this.

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  • JSONP request using jquery $.getJSON not working on well formed JSON.

    - by Antti
    I'm not sure is it possible now from the url I am trying. Please see this url: http://www.heiaheia.com/voimakaksikko/stats.json It always serves the same padding function "voimakaksikkoStats". It is well formed JSON, but I have not been able to load it from remote server. Does it need some work from the server side or can it be loaded with javascript? I think the problems gotta to have something to with that callback function... JQuery is not requirement, but it would be nice. This (callback=voimakaksikkoStats) returns nothing (firebug - net - response), and alert doesn't fire: $.getJSON("http://www.heiaheia.com/voimakaksikko/stats.json?callback=voimakaksikkoStats", function(data){ alert(data); }) but this (callback=?): $.getJSON("http://www.heiaheia.com/voimakaksikko/stats.json?callback=?", function(data){ alert(data); }) returns: voimakaksikkoStats({"Top5Sports":[],"Top5Tests":{"8":"No-exercise ennuste","1":"Painoindeksi","2":"Vy\u00f6t\u00e4r\u00f6n ymp\u00e4rys","10":"Cooperin testi","4":"Etunojapunnerrus"},"Top5CitiesByTests":[],"Top5CitiesByExercises":[],"ExercisesLogged":0,"Top5CitiesByUsers":[""],"TestsTaken":22,"RegisteredUsers":1}); But I cannot access it... In both examples the alert never fires. Can someone help?

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  • Deobfuscating Javascript

    - by David Murdoch
    What is this monstrosity? Anyone know of a way to make it readable? <script type="text/javascript"> //<![CDATA[ <!-- var x="function f(x){var i,o=\"\",l=x.length;for(i=0;i<l;i+=2) {if(i+1<l)o+=" + "x.charAt(i+1);try{o+=x.charAt(i);}catch(e){}}return o;}f(\"ufcnitnof x({)av" + " r,i=o\\\"\\\"o,=l.xelgnhtl,o=;lhwli(e.xhcraoCedtAl(1/)3=!76{)rt{y+xx=l;=+;" + "lc}tahce({)}}of(r=i-l;1>i0=i;--{)+ox=c.ahAr(t)i};erutnro s.buts(r,0lo;)f}\\" + "\"(0),9\\\"\\\\$.;(.34U03\\\\\\\\16\\\\0E\\\\NSCZhC24\\\\03\\\\01\\\\\\\\St" + "DEMPbM02\\\\0C\\\\x#opms58aJ}qb<jb7`17\\\\\\\\hc7s17\\\\\\\\rzEeljdp7m03\\\\"+ "\\\\36\\\\0F\\\\24\\\\06\\\\01\\\\\\\\25\\\\01\\\\02\\\\\\\\26\\\\03\\\\03\\"+ "\\\\\\(W4N02\\\\\\\\24\\\\02\\\\00\\\\\\\\07\\\\0N\\\\14\\\\0P\\\\BI07\\\\0" + "4\\\\00\\\\\\\\02\\\\02\\\\02\\\\\\\\14\\\\06\\\\02\\\\\\\\24\\\\0L\\\\25\\" + "\\06\\\\01\\\\\\\\3:?(>4\\\"\\\\f(;} ornture;}))++(y)^(iAtdeCoarchx.e(odrCh" + "amCro.fngriSt+=;o27=1y%i;+=)y90==(iif){++;i<l;i=0(ior;fthnglex.l=\\\\,\\\\\\"+ "\"=\\\",o iar{vy)x,f(n ioctun\\\"f)\")" ; while(x=eval(x)); //--> //]]> </script>

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