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  • How to find a Window which should be visible on Ubuntu 14.04

    - by Bernard
    In Ubuntu 14.04 I have Keepass2 in my Launchbar. I do execute Keepass and I can see it is executing by a small arrow. With statement : ps - fu bernard | grep keepass2 Also with alt-tab I see Keepass. If I click on the Keepass icon still I am not switched to Keepass. The same happened to me with XAMPP from https://www.apachefriends.org so it seems a general Ubuntu 14.04 problem I execute this in Virtualbox client. If I switch sometimes to other VB client, when I come back the Windows is visible.

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  • Push back rectangle where collision happens

    - by Tifa
    I have a tile collision on a game I am creating but the problem is once a collision happens for example a collision happens in right side my sprite cant move to up and bottom :( thats because i set the speed to 0. I thinks its wrong. here is my code: int startX, startY, endX, endY; float pushx = 0,pushy = 0; // move player if(Gdx.input.isKeyPressed(Input.Keys.LEFT)){ dx=-1; currentWalk = leftWalk; } if(Gdx.input.isKeyPressed(Input.Keys.RIGHT)){ dx=1; currentWalk = rightWalk; } if(Gdx.input.isKeyPressed(Input.Keys.DOWN)){ dy=-1; currentWalk = downWalk; } if(Gdx.input.isKeyPressed(Input.Keys.UP)){ dy=1; currentWalk = upWalk; } sr.setProjectionMatrix(camera.combined); sr.begin(ShapeRenderer.ShapeType.Line); Rectangle koalaRect = rectPool.obtain(); koalaRect.set(player.getX(), player.getY(), pw, ph /2 ); float oldX = player.getX(), oldY = player.getY(); // THIS LINE WAS ADDED player.setXY(player.getX() + dx * Gdx.graphics.getDeltaTime() * 4f, player.getY() + dy * Gdx.graphics.getDeltaTime() * 4f); // THIS LINE WAS MOVED HERE FROM DOWN BELOW if(dx> 0) { startX = endX = (int)(player.getX() + pw); } else { startX = endX = (int)(player.getX() ); } startY = (int)(player.getY()); endY = (int)(player.getY() + ph); getTiles(startX, startY, endX, endY, tiles); for(Rectangle tile: tiles) { sr.rect(tile.x,tile.y,tile.getWidth(),tile.getHeight()); if(koalaRect.overlaps(tile)) { //dx = 0; player.setX(oldX); // THIS LINE CHANGED Gdx.app.log("x","hit " + player.getX() + " " + oldX); break; } } if(dy > 0) { startY = endY = (int)(player.getY() + ph ); } else { startY = endY = (int)(player.getY() ); } startX = (int)(player.getX()); endX = (int)(player.getX() + pw); getTiles(startX, startY, endX, endY, tiles); for(Rectangle tile: tiles) { if(koalaRect.overlaps(tile)) { //dy = 0; player.setY(oldY); // THIS LINE CHANGED //Gdx.app.log("y","hit" + player.getY() + " " + oldY); break; } } sr.rect(koalaRect.x,koalaRect.y,koalaRect.getWidth(),koalaRect.getHeight() / 2); sr.setColor(Color.GREEN); sr.end(); I want to push back the sprite when a collision happens but i have no idea how :D pls help

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  • Optimized algorithm for line-sphere intersection in GLSL

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

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  • Detecting walls or floors in pygame

    - by Serial
    I am trying to make bullets bounce of walls, but I can't figure out how to correctly do the collision detection. What I am currently doing is iterating through all the solid blocks and if the bullet hits the bottom, top or sides, its vector is adjusted accordingly. However, sometimes when I shoot, the bullet doesn't bounce, I think it's when I shoot at a border between two blocks. Here is the update method for my Bullet class: def update(self, dt): if self.can_bounce: #if the bullet hasnt bounced find its vector using the mousclick pos and player pos speed = -10. range = 200 distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]] norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2) direction = [distance[0] / norm, distance[1 ] / norm] bullet_vector = [direction[0] * speed, direction[1] * speed] self.dx = bullet_vector[0] self.dy = bullet_vector[1] #check each block for collision for block in self.game.solid_blocks: last = self.rect.copy() if self.rect.colliderect(block): topcheck = self.rect.top < block.rect.bottom and self.rect.top > block.rect.top bottomcheck = self.rect.bottom > block.rect.top and self.rect.bottom < block.rect.bottom rightcheck = self.rect.right > block.rect.left and self.rect.right < block.rect.right leftcheck = self.rect.left < block.rect.right and self.rect.left > block.rect.left each test tests if it hit the top bottom left or right side of the block its colliding with if self.can_bounce: if topcheck: self.rect = last self.dy *= -1 self.can_bounce = False print "top" if bottomcheck: self.rect = last self.dy *= -1 #Bottom check self.can_bounce = False print "bottom" if rightcheck: self.rect = last self.dx *= -1 #right check self.can_bounce = False print "right" if leftcheck: self.rect = last self.dx *= -1 #left check self.can_bounce = False print "left" else: # if it has already bounced and colliding again kill it self.kill() for enemy in self.game.enemies_list: if self.rect.colliderect(enemy): self.kill() #update position self.rect.x -= self.dx self.rect.y -= self.dy This definitely isn't the best way to do it but I can't think of another way. If anyone has done this or can help that would be awesome!

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  • Trouble with speed and vectors

    - by Eegabooga
    I'm working on adding bullets to my game. Right now I can shoot bullets in the direction that I would like from a ship by getting the ship's angle: int speed = 5; int dx = -(cos(degreesToRadians(ship.angle)) * speed); // rate of change in the x direction int dy = -(sin(degreesToRadians(ship.angle)) * speed); // rate of change in the y direction bulletPosition.addX(dx); // addX(dx) is simply bulletPosition.x += dx bulletPosition.addY(dy); The ship is pretty much the exact same thing, except I use the += operator: int dx += -(cos(degreesToRadians(angle)) * 0.15) int dy += -(sin(degreesToRadians(angle)) * 0.15); shipPosition.addX(dx); shipPosition.addY(dy); I would like to be able to add the ship's velocity to the bullet's velocity, but I'm a little confused as to how should get the speed from the ship's vector. I thought that adding the ship's dx to the bullet's dx like int dx = -(cos(degreesToRadians(ship.angle)) * speed * dx) would work because I'm adding the rate of change of the ship to the rate of change of the bullet, but that doesn't work. So here's the final question: How can I get the speed of my ship and apply it to my bullet's speed? Thanks in advance for all help :)

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  • LibGDX onTouch() method kill on touch

    - by johnny-b
    How can I add this on my application. i want to use the onTouch() method from the implementation of the InputProcessor to kill the enemies on screen. how do i do that? do i have to do anything to the enemy class? please help Thank you M @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { return false; } here is my enemy class public class Bullet extends Sprite { private Vector2 velocity; private float lifetime; public Bullet(float x, float y) { velocity = new Vector2(0, 0); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); velocity.x += dx * delta; velocity.y += dy * delta; } } i am rendering all graphics in a GameRender class and a gameworld class if you need more info please let me know Thank you

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  • My raycaster is putting out strange results, how do I fix it?

    - by JamesK89
    I'm working on a raycaster in ActionScript 3.0 for the fun of it, and as a learning experience. I've got it up and running and its displaying me output as expected however I'm getting this strange bug where rays go through corners of blocks and the edges of blocks appear through walls. Maybe somebody with more experience can point out what I'm doing wrong or maybe a fresh pair of eyes can spot a tiny bug I haven't noticed. Thank you so much for your help! Screenshots: http://i55.tinypic.com/25koebm.jpg http://i51.tinypic.com/zx5jq9.jpg Relevant code: function drawScene() { rays.graphics.clear(); rays.graphics.lineStyle(1, rgba(0x00,0x66,0x00)); var halfFov = (player.fov/2); var numRays:int = ( stage.stageWidth / COLUMN_SIZE ); var prjDist = ( stage.stageWidth / 2 ) / Math.tan(toRad( halfFov )); var angStep = ( player.fov / numRays ); for( var i:int = 0; i < numRays; i++ ) { var rAng = ( ( player.angle - halfFov ) + ( angStep * i ) ) % 360; if( rAng < 0 ) rAng += 360; var ray:Object = castRay(player.position, rAng); drawRaySlice(i*COLUMN_SIZE, prjDist, player.angle, ray); } } function drawRaySlice(sx:int, prjDist, angle, ray:Object) { if( ray.distance >= MAX_DIST ) return; var height:int = int(( TILE_SIZE / (ray.distance * Math.cos(toRad(angle-ray.angle))) ) * prjDist); if( !height ) return; var yTop = int(( stage.stageHeight / 2 ) - ( height / 2 )); if( yTop < 0 ) yTop = 0; var yBot = int(( stage.stageHeight / 2 ) + ( height / 2 )); if( yBot > stage.stageHeight ) yBot = stage.stageHeight; rays.graphics.moveTo( (ray.origin.x / TILE_SIZE) * MINI_SIZE, (ray.origin.y / TILE_SIZE) * MINI_SIZE ); rays.graphics.lineTo( (ray.hit.x / TILE_SIZE) * MINI_SIZE, (ray.hit.y / TILE_SIZE) * MINI_SIZE ); for( var x:int = 0; x < COLUMN_SIZE; x++ ) { for( var y:int = yTop; y < yBot; y++ ) { buffer.setPixel(sx+x, y, clrTable[ray.tile-1] >> ( ray.horz ? 1 : 0 )); } } } function castRay(origin:Point, angle):Object { // Return values var rTexel = 0; var rHorz = false; var rTile = 0; var rDist = MAX_DIST + 1; var rMap:Point = new Point(); var rHit:Point = new Point(); // Ray angle and slope var ra = toRad(angle) % ANGLE_360; if( ra < ANGLE_0 ) ra += ANGLE_360; var rs = Math.tan(ra); var rUp = ( ra > ANGLE_0 && ra < ANGLE_180 ); var rRight = ( ra < ANGLE_90 || ra > ANGLE_270 ); // Ray position var rx = 0; var ry = 0; // Ray step values var xa = 0; var ya = 0; // Ray position, in map coordinates var mx:int = 0; var my:int = 0; var mt:int = 0; // Distance var dx = 0; var dy = 0; var ds = MAX_DIST + 1; // Horizontal intersection if( ra != ANGLE_180 && ra != ANGLE_0 && ra != ANGLE_360 ) { ya = ( rUp ? TILE_SIZE : -TILE_SIZE ); xa = ya / rs; ry = int( origin.y / TILE_SIZE ) * ( TILE_SIZE ) + ( rUp ? TILE_SIZE : -1 ); rx = origin.x + ( ry - origin.y ) / rs; mx = 0; my = 0; while( mx >= 0 && my >= 0 && mx < world.size.x && my < world.size.y ) { mx = int( rx / TILE_SIZE ); my = int( ry / TILE_SIZE ); mt = getMapTile(mx,my); if( mt > 0 && mt < 9 ) { dx = rx - origin.x; dy = ry - origin.y; ds = ( dx * dx ) + ( dy * dy ); if( rDist >= MAX_DIST || ds < rDist ) { rDist = ds; rTile = mt; rMap.x = mx; rMap.y = my; rHit.x = rx; rHit.y = ry; rHorz = true; rTexel = int(rx % TILE_SIZE) } break; } rx += xa; ry += ya; } } // Vertical intersection if( ra != ANGLE_90 && ra != ANGLE_270 ) { xa = ( rRight ? TILE_SIZE : -TILE_SIZE ); ya = xa * rs; rx = int( origin.x / TILE_SIZE ) * ( TILE_SIZE ) + ( rRight ? TILE_SIZE : -1 ); ry = origin.y + ( rx - origin.x ) * rs; mx = 0; my = 0; while( mx >= 0 && my >= 0 && mx < world.size.x && my < world.size.y ) { mx = int( rx / TILE_SIZE ); my = int( ry / TILE_SIZE ); mt = getMapTile(mx,my); if( mt > 0 && mt < 9 ) { dx = rx - origin.x; dy = ry - origin.y; ds = ( dx * dx ) + ( dy * dy ); if( rDist >= MAX_DIST || ds < rDist ) { rDist = ds; rTile = mt; rMap.x = mx; rMap.y = my; rHit.x = rx; rHit.y = ry; rHorz = false; rTexel = int(ry % TILE_SIZE); } break; } rx += xa; ry += ya; } } return { angle: angle, distance: Math.sqrt(rDist), hit: rHit, map: rMap, tile: rTile, horz: rHorz, origin: origin, texel: rTexel }; }

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  • libgdx rotation (animation, arrays) issues and help needed

    - by johnny-b
    well i am a noob at java and libgdx. i got the homing bullet working with the help of someone. now i am smashing my head as to how i can make it rotate so it faces the ball (which is the main character) when it goes around it or when it is coming towards it. the bullet is facing <--- and the code below is what i have done so far. also i used sprites for the bullet and also animation method. Also how do i make it an array/arraylist which is best so i can have multiple bullets at random or placed places. i tried many things nothing workd :( thank you for the help. // below is the bullet or enemy if you want to call it. public class Bullet extends Sprite { public static final float BULLET_HOMING = 6000; public static final float BULLET_SPEED = 300; private Vector2 velocity; private float lifetime; public Bullet(float x, float y) { velocity = new Vector2(0, 0); setPosition(x, y); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); dx /= distToTarget; dy /= distToTarget; dx *= BULLET_HOMING; dy *= BULLET_HOMING; velocity.x += dx * delta; velocity.y += dy * delta; float vMag = (float) Math.sqrt(velocity.x * velocity.x + velocity.y * velocity.y); velocity.x /= vMag; velocity.y /= vMag; velocity.x *= BULLET_SPEED; velocity.y *= BULLET_SPEED; Vector2 v = velocity.cpy().scl(delta); setPosition(getX() + v.x, getY() + v.y); setOriginCenter(); setRotation(velocity.angle()); lifetime += delta; setRegion(AssetLoader.bulletAnimation.getKeyFrame(lifetime)); } } // this is where i load the images. public class AssetLoader { public static Animation bulletAnimation; public static Sprite bullet1, bullet2; public static void load() { texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, aims); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); } public static void dispose() { // We must dispose of the texture when we are finished. texture.dispose(); } // this is for the rendering of the images etc public class GameRenderer { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); // Disable transparency // This is good for performance when drawing images that do not require // transparency. batcher.disableBlending(); // The ball needs transparency, so we enable that again. batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); // End SpriteBatch batcher.end(); } } // this is to load the image etc on the screen i guess public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } so there is the whole thing. the images are loaded via the AssetLoader then to the GameRenderer and GameWorld via the Bullet class. i am guessing that is how it is. sorry newbie so still learning. thank you in advace for the help or any advice.

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  • Which of these algorithms is best for my goal?

    - by JonathonG
    I have created a program that restricts the mouse to a certain region based on a black/white bitmap. The program is 100% functional as-is, but uses an inaccurate, albeit fast, algorithm for repositioning the mouse when it strays outside the area. Currently, when the mouse moves outside the area, basically what happens is this: A line is drawn between a pre-defined static point inside the region and the mouse's new position. The point where that line intersects the edge of the allowed area is found. The mouse is moved to that point. This works, but only works perfectly for a perfect circle with the pre-defined point set in the exact center. Unfortunately, this will never be the case. The application will be used with a variety of rectangles and irregular, amorphous shapes. On such shapes, the point where the line drawn intersects the edge will usually not be the closest point on the shape to the mouse. I need to create a new algorithm that finds the closest point to the mouse's new position on the edge of the allowed area. I have several ideas about this, but I am not sure of their validity, in that they may have far too much overhead. While I am not asking for code, it might help to know that I am using Objective C / Cocoa, developing for OS X, as I feel the language being used might affect the efficiency of potential methods. My ideas are: Using a bit of trigonometry to project lines would work, but that would require some kind of intense algorithm to test every point on every line until it found the edge of the region... That seems too resource intensive since there could be something like 200 lines that would have each have to have as many as 200 pixels checked for black/white.... Using something like an A* pathing algorithm to find the shortest path to a black pixel; however, A* seems resource intensive, even though I could probably restrict it to only checking roughly in one direction. It also seems like it will take more time and effort than I have available to spend on this small portion of the much larger project I am working on, correct me if I am wrong and it would not be a significant amount of code (100 lines or around there). Mapping the border of the region before the application begins running the event tap loop. I think I could accomplish this by using my current line-based algorithm to find an edge point and then initiating an algorithm that checks all 8 pixels around that pixel, finds the next border pixel in one direction, and continues to do this until it comes back to the starting pixel. I could then store that data in an array to be used for the entire duration of the program, and have the mouse re-positioning method check the array for the closest pixel on the border to the mouse target position. That last method would presumably execute it's initial border mapping fairly quickly. (It would only have to map between 2,000 and 8,000 pixels, which means 8,000 to 64,000 checked, and I could even permanently store the data to make launching faster.) However, I am uncertain as to how much overhead it would take to scan through that array for the shortest distance for every single mouse move event... I suppose there could be a shortcut to restrict the number of elements in the array that will be checked to a variable number starting with the intersecting point on the line (from my original algorithm), and raise/lower that number to experiment with the overhead/accuracy tradeoff. Please let me know if I am over thinking this and there is an easier way that will work just fine, or which of these methods would be able to execute something like 30 times per second to keep mouse movement smooth, or if you have a better/faster method. I've posted relevant parts of my code below for reference, and included an example of what the area might look like. (I check for color value against a loaded bitmap that is black/white.) // // This part of my code runs every single time the mouse moves. // CGPoint point = CGEventGetLocation(event); float tX = point.x; float tY = point.y; if( is_in_area(tX,tY, mouse_mask)){ // target is inside O.K. area, do nothing }else{ CGPoint target; //point inside restricted region: float iX = 600; // inside x float iY = 500; // inside y // delta to midpoint between iX,iY and tX,tY float dX; float dY; float accuracy = .5; //accuracy to loop until reached do { dX = (tX-iX)/2; dY = (tY-iY)/2; if(is_in_area((tX-dX),(tY-dY),mouse_mask)){ iX += dX; iY += dY; } else { tX -= dX; tY -= dY; } } while (abs(dX)>accuracy || abs(dY)>accuracy); target = CGPointMake(roundf(tX), roundf(tY)); CGDisplayMoveCursorToPoint(CGMainDisplayID(),target); } Here is "is_in_area(int x, int y)" : bool is_in_area(NSInteger x, NSInteger y, NSBitmapImageRep *mouse_mask){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSUInteger pixel[4]; [mouse_mask getPixel:pixel atX:x y:y]; if(pixel[0]!= 0){ [pool release]; return false; } [pool release]; return true; }

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  • Resolving bounding box collision detection

    - by ndg
    I'm working on a simple collision detection and resolution method for a 2d tile-based bounding box system. Collision appears to work correctly, but I'm having issues with resolving a collision after it has happened. Essentially what I'm attempting to do is very similar to this approach. The problem I'm experiencing is that because objects can be traveling with both horizontal and vertical velocity, my resolution code causes the object to jump incorrectly. I've drawn the following annotation to explain my issue. In this example, because my object has both horizontal and vertical velocity, my object (which is heading upwards and collides with the bottom of a tile) has it's position altered twice: To correctly adjust it's vertical position to be beneath the tile. To incorrectly adjust it's horizontal position to be to the left of the tile. Below is my collision/resolution code in full: function intersects(x1, y1, w1, h1, x2, y2, w2, h2) { w2 += x2; w1 += x1; if (x2 > w1 || x1 > w2) return false; h2 += y2; h1 += y1; if (y2 > h1 || y1 > h2) return false; return true; } for(var y = 0; y < this.game.level.tiles.length; y++) { for(var x = 0; x < this.game.level.tiles[y].length; x++) { var tile = this.game.level.getTile(x, y); if(tile) { if( this.velocity.x > 0 && intersects(this.position.x+dx+this.size.w, this.position.y+dy, 1, this.size.h, x*tileSize, y*tileSize, tileSize, tileSize) ) { this.position.x = ((x*tileSize)-this.size.w); hitSomething = true; break; } else if( this.velocity.x < 0 && intersects(this.position.x+dx, this.position.y+dy, 1, this.size.h, x*tileSize, y*tileSize, tileSize, tileSize) ) { this.position.x = ((x*tileSize)+tileSize); hitSomething = true; break; } if( this.velocity.y > 0 && intersects(this.position.x+dx, this.position.y+dy+this.size.h, this.size.w, 1, x*tileSize, y*tileSize, tileSize, tileSize) ) { this.position.y = ((y*tileSize)-this.size.h); hitSomething = true; break; } else if( this.velocity.y < 0 && intersects(this.position.x+dx, this.position.y+dy, this.size.w, 1, x*tileSize, y*tileSize, tileSize, tileSize) ) { this.position.y = ((y*tileSize)+tileSize); hitSomething = true; break; } } } } if(hitSomething) { this.velocity.x = this.velocity.y = 0; dx = dy = 0; this.setJumping(false); }

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  • Determine if getPixel() value is greater than or less than 50% gray

    - by cmal
    I am trying to loop through a bitmap and determine if each pixel is lighter or darker than gray using getPixel(). Problem is, I am not sure how to tell whether the value returned by getPixel() is darker or lighter than gray. Neutral gray is about 0x808080 or R:127, G:127, B:127. How would I need to modify the code below to accurately determine this? for (var dx:int=0; dx < objectWidth; dx++) { for (var dy:int=0; dy < objectHeight; dy++) { if (testBmd.getPixel(dx, dy) > GRAY) { trace("Lighter than gray!"); } else { trace("Darker than gray!"); } } }

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  • The Math of a Jump in a 2D game.

    - by ONi
    I have been all around with this question and I can't find the correct answer! So, behold, the description of my question: I'm working in J2ME, I have my gameloop that do the following: public void run() { Graphics g = this.getGraphics(); while (running) { long diff = System.currentTimeMillis() - lastLoop; lastLoop = System.currentTimeMillis(); input(); this.level.doLogic(); render(g, diff); try { Thread.sleep(10); } catch (InterruptedException e) { stop(e); } } } so it's just a basic gameloop, the doLogic() function calls for all the logic functions of the characters in the scene and render(g, diff) calls the animateChar function of every character on scene, following this, the animChar function in the Character class sets up everything in the screen as this: protected void animChar(long diff) { this.checkGravity(); this.move((int) ((diff * this.dx) / 1000), (int) ((diff * this.dy) / 1000)); if (this.acumFrame > this.framerate) { this.nextFrame(); this.acumFrame = 0; } else { this.acumFrame += diff; } } This ensures me that everything must to move according to the time that the machine takes to go from cycle to cycle (remember it's a phone, not a gaming rig). I'm sure it's not the most efficient way to achieve this behavior so I'm totally open for criticism of my programming skills in the comments, but here my problem: When I make I character jump, what I do is that I put his dy to a negative value, say -200 and I set the boolean jumping to true, that makes the character go up, and then I have this function called checkGravity() that ensure that everything that goes up has to go down, checkGravity also checks for the character being over platforms so I will strip it down a little for the sake of your time: public void checkGravity() { if (this.jumping) { this.jumpSpeed += 10; if (this.jumpSpeed > 0) { this.jumping = false; this.falling = true; } this.dy = this.jumpSpeed; } if (this.falling) { this.jumpSpeed += 10; if (this.jumpSpeed > 200) this.jumpSpeed = 200; this.dy = this.jumpSpeed; if (this.collidesWithPlatform()) { this.falling = false; this.standing = true; this.jumping = false; this.jumpSpeed = 0; this.dy = this.jumpSpeed; } } } So, the problem is, that this function updates the dy regardless of the diff, making the characters fly like Superman in slow machines, and I have no idea how to implement the diff factor so that when a character is jumping, his speed decrement in a proportional way to the game speed. Can anyone help me fix this issue? or give me pointers on how to make a 2D Jump in J2ME the right way. Thank you very much for your time.

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  • The correct usage of nested #pragma omp for directives

    - by GoldenLee
    The following code runs like a charm before OpenMP parallelization was applied. In fact, the following code was in a state of endless loop! I'm sure that's result from my incorrect use to the OpenMP directives. Would you please show me the correct way? Thank you very much. #pragma omp parallel for for (int nY = nYTop; nY <= nYBottom; nY++) { for (int nX = nXLeft; nX <= nXRight; nX++) { // Use look-up table for performance dLon = theApp.m_LonLatLUT.LonGrid()[nY][nX] + m_FavoriteSVISSRParams.m_dNadirLon; dLat = theApp.m_LonLatLUT.LatGrid()[nY][nX]; // If you don't want to use longitude/latitude look-up table, uncomment the following line //NOMGeoLocate.XYToGEO(dLon, dLat, nX, nY); if (dLon > 180 || dLat > 180) { continue; } if (Navigation.GeoToXY(dX, dY, dLon, dLat, 0) > 0) { continue; } // Skip void data scanline dY = dY - nScanlineOffset; // Compute coefficients as well as its four neighboring points' values nX1 = int(dX); nX2 = nX1 + 1; nY1 = int(dY); nY2 = nY1 + 1; dCx = dX - nX1; dCy = dY - nY1; dP1 = pIRChannelData->operator [](nY1)[nX1]; dP2 = pIRChannelData->operator [](nY1)[nX2]; dP3 = pIRChannelData->operator [](nY2)[nX1]; dP4 = pIRChannelData->operator [](nY2)[nX2]; // Bilinear interpolation usNomDataBlock[nY][nX] = (unsigned short)BilinearInterpolation(dCx, dCy, dP1, dP2, dP3, dP4); } }

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  • How to make a pause before continuing method

    - by user1766728
    Now, I know that this has been asked, but I need to know how to do this NOT on html or anything. Heres my code, not including all of the other java files. package rtype; import java.awt.Image; import java.awt.event.KeyEvent; import java.util.ArrayList; import javax.swing.ImageIcon; public class aa { private int xd; private int yd; private int dx; private int dy; private int x; private int y; private Image image; private ArrayList missiles; private final int CRAFT_SIZE = 70; public aa() { ImageIcon ii = new ImageIcon(this.getClass().getResource("/aa.png")); image = ii.getImage(); missiles = new ArrayList(); x = 10; y = 10; xd = -14; yd = 140; } public void move() { if(y >=xd) y += dx; else if(y < xd) y += 1; if(y <=yd) y += dy; else if(y > yd) y += -1; } public int getX() { return x; } public int getY() { return y; } public Image getImage() { return image; } public ArrayList getMissiles() { return missiles; } public void keyPressed(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_SPACE) { fire(); } if (key == KeyEvent.VK_UP) { dy = -1; } if (key == KeyEvent.VK_DOWN) { dy = 1; } if (key == KeyEvent.VK_RIGHT) { yd++; } if (key == KeyEvent.VK_LEFT) { yd--; } if (key == KeyEvent.VK_W) { xd++; } if (key == KeyEvent.VK_S) { xd--; } } public void fire() { try{ missiles.add(new Missle(x + CRAFT_SIZE, y + CRAFT_SIZE)); }catch(Exception e){} } public void keyReleased(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_UP) { dy = 0; } if (key == KeyEvent.VK_DOWN) { dy = 0; } } } So, at the method, fire(), I want to make it delay between shots. HOW? sorry if this is n00bish

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  • Building a Flash Platformer

    - by Jonathan O
    I am basically making a game where the whole game is run in the onEnterFrame method. This is causing a delay in my code that makes debugging and testing difficult. Should programming an entire platformer in this method be efficient enough for me to run hundreds of lines of code? Also, do variables in flash get updated immediately? Are there just lots of threads listening at the same time? Here is the code... stage.addEventListener(Event.ENTER_FRAME, onEnter); function onEnter(e:Event):void { //Jumping if (Yoshi.y > groundBaseLevel) { dy = 0; canJump = true; onGround = true; //This line is not updated in time } if (Key.isDown(Key.UP) && canJump) { dy = -10; canJump = false; onGround = false; //This line is not updated in time } if(!onGround) { dy += gravity; Yoshi.y += dy; } //limit screen boundaries //character movement if (! Yoshi.hitTestObject(Platform)) //no collision detected { if (Key.isDown(Key.RIGHT)) { speed += 4; speed *= friction; Yoshi.x = Yoshi.x + movementIncrement + speed; Yoshi.scaleX = 1; Yoshi.gotoAndStop('Walking'); } else if (Key.isDown(Key.LEFT)) { speed -= 4; speed *= friction; Yoshi.x = Yoshi.x - movementIncrement + speed; Yoshi.scaleX = -1; Yoshi.gotoAndStop('Walking'); } else { speed *= friction; Yoshi.x = Yoshi.x + speed; Yoshi.gotoAndStop('Still'); } } else //bounce back collision detected { if(Yoshi.hitTestPoint(Platform.x - Platform.width/2, Platform.y - Platform.height/2, false)) { trace('collision left'); Yoshi.x -=20; } if(Yoshi.hitTestPoint(Platform.x, Platform.y - Platform.height/2, false)) { trace('collision top'); onGround=true; //This update is not happening in time speed = 0; } } }

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  • Android, how important is deltaTime?

    - by iQue
    Im making a game that is getting pretty big and sometimes my thread has to skip a frame, so far I'm not using deltaTime for setting the speed of my different objects in the game because it's still not a big enough game for it to matter imo. But its getting bigger then I planned, so my question is, how important is delta Time? If I should use delta time there is a problem, since speedX and speedY are integers(they have to be for eclipse to let you make a rectangle of them), I cant add delta time very functionally as far as I understand, but might be wrong? Ive tried adding deltaTime to the code below, and sometimes my enemies just not move after spawn, they just stand there and run in the same place Will add an some code for how I set / use speed: public void update(int dx, int dy) { double theta = 180.0 / Math.PI * Math.atan2(-(y - controls.pointerPosition.y), controls.pointerPosition.x - x); x +=dx * Math.cos(Math.toRadians(theta)); y +=dy * Math.sin(Math.toRadians(theta)); currentFrame = ++currentFrame % BMP_COLUMNS; } public void draw(Canvas canvas) { int srcX = currentFrame * width; int srcY = 1 * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bitmap, src, dst, null); } So if someone with some experience with this has any thoughts, please share. Thank you! Changed code: public void update(int dx, int dy, float delta) { double theta = 180.0 / Math.PI * Math.atan2(-(y - controls.pointerPosition.y), controls.pointerPosition.x - x); double speedX = delta * dx * Math.cos(Math.toRadians(theta)); double speedY = delta * dy * Math.sin(Math.toRadians(theta)); x += speedX; y += speedY; currentFrame = ++currentFrame % BMP_COLUMNS; } public void draw(Canvas canvas) { int srcX = currentFrame * width; int srcY = 1 * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bitmap, src, dst, null); } with this code my enemies move like before, except they wont move to the right (wont increment x), all other directions work.

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  • rotate sprite and shooting bullets from the end of a cannon

    - by Alberto
    Hi all i have a problem in my Andengine code, I need , when I touch the screen, shoot a bullet from the cannon (in the same direction of the cannon) The cannon rotates perfectly but when I touch the screen the bullet is not created at the end of the turret This is my code: private void shootProjectile(final float pX, final float pY){ int offX = (int) (pX-canon.getSceneCenterCoordinates()[0]); int offY = (int) (pY-canon.getSceneCenterCoordinates()[1]); if (offX <= 0) return ; if(offY>=0) return; double X=canon.getX()+canon.getWidth()*0,5; double Y=canon.getY()+canon.getHeight()*0,5 ; final Sprite projectile; projectile = new Sprite( (float) X, (float) Y, mProjectileTextureRegion,this.getVertexBufferObjectManager() ); mMainScene.attachChild(projectile); int realX = (int) (mCamera.getWidth()+ projectile.getWidth()/2.0f); float ratio = (float) offY / (float) offX; int realY = (int) ((realX*ratio) + projectile.getY()); int offRealX = (int) (realX- projectile.getX()); int offRealY = (int) (realY- projectile.getY()); float length = (float) Math.sqrt((offRealX*offRealX)+(offRealY*offRealY)); float velocity = (float) 480.0f/1.0f; float realMoveDuration = length/velocity; MoveModifier modifier = new MoveModifier(realMoveDuration,projectile.getX(), realX, projectile.getY(), realY); projectile.registerEntityModifier(modifier); } @Override public boolean onSceneTouchEvent(Scene pScene, TouchEvent pSceneTouchEvent) { if (pSceneTouchEvent.getAction() == TouchEvent.ACTION_MOVE){ double dx = pSceneTouchEvent.getX() - canon.getSceneCenterCoordinates()[0]; double dy = pSceneTouchEvent.getY() - canon.getSceneCenterCoordinates()[1]; double Radius = Math.atan2(dy,dx); double Angle = Radius * 180 / Math.PI; canon.setRotation((float)Angle); return true; } else if (pSceneTouchEvent.getAction() == TouchEvent.ACTION_DOWN){ final float touchX = pSceneTouchEvent.getX(); final float touchY = pSceneTouchEvent.getY(); double dx = pSceneTouchEvent.getX() - canon.getSceneCenterCoordinates()[0]; double dy = pSceneTouchEvent.getY() - canon.getSceneCenterCoordinates()[1]; double Radius = Math.atan2(dy,dx); double Angle = Radius * 180 / Math.PI; canon.setRotation((float)Angle); shootProjectile(touchX, touchY); } return false; } Anyone know how to calculate the coordinates (X,Y) of the end of the barrel to draw the bullet?

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  • box2d resize bodies arround point

    - by philipp
    I have a compound object, consisting of a b2Body, vector-graphics and a list polygons which describe the b2body's shapes. This object has its own transformation matrix to centralize the storage of transformations. So far everything is working quiet fine, even scaling works, but not if i scale around a point. In the initialization phase of the object it is scaled around a point. This happens in this order: transform the main matrix transform the vector graphics and the polygons recreate the b2Body After this function ran, the shapes and all the graphics are exactly where they should be, BUT: after the first steps of the b2World the graphical stuff moves away from the body. When I ran the debugger I found out that the position of the body is 0/0 the red dot shows the center of scaling. the first image shows the basic setup and the second the final position of the graphics. This distance stays constant for the rest of the simulation. If I set the position via myBody.SetPosition( sx, sy ); the whole scenario just plays a bit more distant for the origin. Any Idea how to fix this? EDIT:: I came deeper down to the problem and it lies in the fact that i must not scale the transform matrix for the b2body shapes around the center, but set the b2body's position back to the point after scaling. But how can I calculate that point? EDIT 2 :: I came ever deeper down to it, even solved it, but this is a slow solution and i hope that there is somebody who understands what formula I need. assuming to have a set polygons relative to an origin as basis shapes for a b2body: scaling the whole object around a certain point is done in the following steps: i scale everything around the center except the polygons i create a clone of the polygons matrix i scale this clone around the point i calculate dx, dy as difference of clone.tx - original.tx and clone.ty - original.ty i scale the original polygon matrix NOT around the point i recreate the body i create the fixture i set the position of the body to dx and dy done! So what i an interested in is a formula for dx and dy without cloning matrices, scaling the clone around a point, getting dx and dy and finally scale the vertex matrix.

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  • 2D Collision in Canvas - Balls Overlapping When Velocity is High

    - by kushsolitary
    I am doing a simple experiment in canvas using Javascript in which some balls will be thrown on the screen with some initial velocity and then they will bounce on colliding with each other or with the walls. I managed to do the collision with walls perfectly but now the problem is with the collision with other balls. I am using the following code for it: //Check collision between two bodies function collides(b1, b2) { //Find the distance between their mid-points var dx = b1.x - b2.x, dy = b1.y - b2.y, dist = Math.round(Math.sqrt(dx*dx + dy*dy)); //Check if it is a collision if(dist <= (b1.r + b2.r)) { //Calculate the angles var angle = Math.atan2(dy, dx), sin = Math.sin(angle), cos = Math.cos(angle); //Calculate the old velocity components var v1x = b1.vx * cos, v2x = b2.vx * cos, v1y = b1.vy * sin, v2y = b2.vy * sin; //Calculate the new velocity components var vel1x = ((b1.m - b2.m) / (b1.m + b2.m)) * v1x + (2 * b2.m / (b1.m + b2.m)) * v2x, vel2x = (2 * b1.m / (b1.m + b2.m)) * v1x + ((b2.m - b1.m) / (b2.m + b1.m)) * v2x, vel1y = v1y, vel2y = v2y; //Set the new velocities b1.vx = vel1x; b2.vx = vel2x; b1.vy = vel1y; b2.vy = vel2y; } } You can see the experiment here. The problem is, some balls overlap each other and stick together while some of them rebound perfectly. I don't know what is causing this issue. Here's my balls object if that matters: function Ball() { //Random Positions this.x = 50 + Math.random() * W; this.y = 50 + Math.random() * H; //Random radii this.r = 15 + Math.random() * 30; this.m = this.r; //Random velocity components this.vx = 1 + Math.random() * 4; this.vy = 1 + Math.random() * 4; //Random shade of grey color this.c = Math.round(Math.random() * 200); this.draw = function() { ctx.beginPath(); ctx.fillStyle = "rgb(" + this.c + ", " + this.c + ", " + this.c + ")"; ctx.arc(this.x, this.y, this.r, 0, Math.PI*2, false); ctx.fill(); ctx.closePath(); } }

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  • LibGDX onTouch() method Array and flip method

    - by johnny-b
    How can I add this on my application. i want to use the onTouch() method from the implementation of the InputProcessor to kill the enemies on screen. how do i do that? do i have to do anything to the enemy class? also i am trying to add a Array of enemies and it keeps throwing exceptions or the bullet now is facing LEFT <--- again after I used the flip method in the bullet class. All the code is below so please anyone feel free to have a look thanks. please help Thank you M // This is the bullet class. public class Bullet extends Sprite { public static final float BULLET_HOMING = 6000; public static final float BULLET_SPEED = 300; private Vector2 velocity; private float lifetime; private Rectangle bul; public Bullet(float x, float y) { velocity = new Vector2(0, 0); setPosition(x, y); AssetLoader.bullet1.flip(true, false); AssetLoader.bullet2.flip(true, false); setSize(AssetLoader.bullet1.getWidth(), AssetLoader.bullet1.getHeight()); bul = new Rectangle(); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); dx /= distToTarget; dy /= distToTarget; dx *= BULLET_HOMING; dy *= BULLET_HOMING; velocity.x += dx * delta; velocity.y += dy * delta; float vMag = (float) Math.sqrt(velocity.x * velocity.x + velocity.y * velocity.y); velocity.x /= vMag; velocity.y /= vMag; velocity.x *= BULLET_SPEED; velocity.y *= BULLET_SPEED; bul.set(getX(), getY(), getOriginX(), getOriginY()); Vector2 v = velocity.cpy().scl(delta); setPosition(getX() + v.x, getY() + v.y); setOriginCenter(); setRotation(velocity.angle()); } public Rectangle getBounds() { return bul; } public Rectangle getBounds1() { return this.getBoundingRectangle(); } } // This is the class where i load all the images from public class AssetLoader { public static Texture texture; public static TextureRegion bg, ball1, ball2; public static Animation bulletAnimation, ballAnimation; public static Sprite bullet1, bullet2; public static void load() { texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bg = new TextureRegion(texture, 80, 421, 395, 30); bg.flip(false, true); ball1 = new TextureRegion(texture, 0, 321, 32, 32); ball1.flip(false, true); ball2 = new TextureRegion(texture, 32, 321, 32, 32); ball2.flip(false, true); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); TextureRegion[] balls = { ball1, ball2 }; ballAnimation = new Animation(0.16f, balls); ballAnimation.setPlayMode(Animation.PlayMode.LOOP); } Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, aims); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); } public static void dispose() { texture.dispose(); } // This is for the rendering or drawing onto the screen/canvas. public class GameRenderer { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); batcher.disableBlending(); batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY(), bullet.getOriginX(), bullet.getOriginY(), bullet.getWidth(), bullet.getHeight(), 1.0f, 1.0f, bullet.getRotation()); // End SpriteBatch batcher.end(); } } // this is to load the image etc on the screen i guess public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } //This is the input handler class public class InputHandler implements InputProcessor { private Ball myBall; private Bullet bullet; private GameRenderer aims; // Ask for a reference to the Soldier when InputHandler is created. public InputHandler(Ball ball) { myBall = ball; } @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { return false; } @Override public boolean keyDown(int keycode) { return false; } @Override public boolean keyUp(int keycode) { return false; } @Override public boolean keyTyped(char character) { return false; } @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { return false; } @Override public boolean touchDragged(int screenX, int screenY, int pointer) { return false; } @Override public boolean mouseMoved(int screenX, int screenY) { return false; } @Override public boolean scrolled(int amount) { return false; } } i am rendering all graphics in a GameRender class and a gameworld class if you need more info please let me know I am trying to make the array work but keep finding that when an array is initialized then the bullet fips back to the original and ends up being backwards???? and if I create an array I keep getting Exceptions throw??? Thank you for any help given.

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  • Determining the angle to fire a shot when target and shooter moves, and bullet moves with shooter velocity added in

    - by Azaral
    I saw this question: Predicting enemy position in order to have an object lead its target and followed the link in the answer to stack overflow. In the stack overflow page I used the 2nd answer, the one that is a large mathematical derivation. My situation is a little different though. My first question though is will the answer provided in the stack overflow page even work to begin with, assuming the original circumstances of moving target and stationary shooter. My situation is a little different than that situation. My target moves, the shooter moves, and the bullets from the shooter start off with the velocities in x and y added to the bullets' x and y velocities. If you are sliding to the right, the bullets will remain in front of you as you move so as long as your velocity remains constant. What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player. Unless the player and enemy is stationary, the velocity from the ship adding to the velocity of the bullets will cause a miss. I'd rather like to prevent that. I used the formula in the stack overflow answer and did what I thought were the appropriate adjustments. I've been banging at this for the last four hours and I just can't make it click. It is probably something really simple and boneheaded that I am missing (that seems to be a lot of my problems lately). Here is the solution presented from the stack overflow answer: It boils down to solving a quadratic equation of the form: a * sqr(x) + b * x + c == 0 Note that by sqr I mean square, as opposed to square root. Use the following values: a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X) + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y) Now we can look at the discriminant to determine if we have a possible solution. disc := sqr(b) - 4 * a * c If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions: t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a) Note that if disc == 0 then t1 and t2 are equal. If there are no other considerations such as intervening obstacles, simply choose the smaller positive value. (Negative t values would require firing backward in time to use!) Substitute the chosen t value back into the target's position equations to get the coordinates of the leading point you should be aiming at: aim.X := t * target.velocityX + target.startX aim.Y := t * target.velocityY + target.startY Here is my code, after being corrected by Sam Hocevar (thank you again for your help!). It still doesn't work. For some reason it never enters the section of code inside the if(disc = 0) (obviously because it is always less than zero but...). However, if I plug the numbers from my game log on the enemy and player positions and velocities it outputs a valid firing solution. I have looked at the code side by side a couple of times now and I can't find any differences. There has got to be something simple I'm missing here. If someone else could look at this code and determine what is going on here I'd appreciate it. I know it's not going through that section because if it were, shouldShoot would become true and the enemy would be blasting away at the player. This section calls the function in question, CalculateShootHeading() if(shouldMove) { UseEngines(); } x += xVelocity; y += yVelocity; CalculateShootHeading(); if(shouldShoot) { ShootWeapons(); } UpdateWeapons(); This is CalculateShootHeading(). This is inside the enemy class so x and y are the enemy's x and y and the same with velocity. One output from my game log gives Player X = 2108, Player Y = -180.956, Player X velocity = 10.9949, Player Y Velocity = -6.26017, Enemy X = 1988.31, Enemy Y = -339.051, Enemy X velocity = 1.81666, Enemy Y velocity = -9.67762, 0 enemy projectiles. The output from the console tester is Bullet position = 2210.49, -239.313 and Player Position = 2210.49, -239.313. This doesn't make any sense. The only thing that could be different is the code or the input into my function in the game and I've checked that and I don't think that it is wrong as it's updated before this and never changed. float const bulletSpeed = 30.f; float const dx = playerX - x; float const dy = playerY - y; float const vx = playerXVelocity - xVelocity; float const vy = playerYVelocity - yVelocity; float const a = vx * vx + vy * vy - bulletSpeed * bulletSpeed; float const b = 2.f * (vx * dx + vy * dy); float const c = dx * dx + dy * dy; float const disc = b * b - 4.f * a * c; shouldShoot = false; if (disc >= 0.f) { float t0 = (-b - std::sqrt(disc)) / (2.f * a); float t1 = (-b + std::sqrt(disc)) / (2.f * a); if (t0 < 0.f || (t1 < t0 && t1 >= 0.f)) { t0 = t1; } if (t0 >= 0.f) { float shootx = vx + dx / t0; float shooty = vy + dy / t0; heading = std::atan2(shooty, shootx) * RAD2DEGREE; } shouldShoot = true; }

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  • lwjgl isKeyDown canceling out other keys

    - by AKrush95
    While trying to create a simple game where a square is manipulated via the keyboard keys, I have come across a small, rather irritating problem. I would like it to work so that when the opposite directional key is pressed, the character will stop; the character may move the other two directions while stopped in this situation. This works perfectly with LEFT and RIGHT held down; the player may move UP or DOWN. If UP and DOWN are held down, however, the player will not move, nor will Java recognize that the LEFT or RIGHT keys were pressed. import java.util.ArrayList; import java.util.Random; import org.lwjgl.*; import org.lwjgl.input.Keyboard; import org.lwjgl.opengl.*; import static org.lwjgl.opengl.GL11.*; public class Main { private Man p; private ArrayList<Integer> keysDown, keysUp; public Main() { try { Display.setDisplayMode(new DisplayMode(640, 480)); Display.setTitle("LWJGLHelloWorld"); Display.create(); } catch (LWJGLException e) { e.printStackTrace(); } p = new Man(0, 0); keysDown = new ArrayList<>(); keysUp = new ArrayList<>(); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0, 640, 480, 0, 1, -1); glMatrixMode(GL_MODELVIEW); while (!Display.isCloseRequested()) { glClear(GL_COLOR_BUFFER_BIT); checkKeys(); p.draw(); Display.update(); Display.sync(60); } Display.destroy(); } public void checkKeys() { ArrayList<Integer> keys = new ArrayList<>(); keys.add(Keyboard.KEY_A); keys.add(Keyboard.KEY_D); keys.add(Keyboard.KEY_W); keys.add(Keyboard.KEY_S); for (int key : keys) { if (Keyboard.isKeyDown(key)) keysDown.add(key); else keysUp.add(key); } keysDown.removeAll(keysUp); keysUp = new ArrayList<>(); int speed = 4; int dx = 0; int dy = 0; if (keysDown.contains(keys.get(2))) { System.out.println("keyUP"); dy -= speed; } if (keysDown.contains(keys.get(3))) { System.out.println("keyDOWN"); dy += speed; } if (keysDown.contains(keys.get(0))) { System.out.println("keyLEFT"); dx -= speed; } if (keysDown.contains(keys.get(1))) { System.out.println("keyRIGHT"); dx += speed; } //if (keysDown.contains(keys.get(0)) && keysDown.contains(keys.get(1))) dx = 0; //if (keysDown.contains(keys.get(2)) && keysDown.contains(keys.get(3))) dy = 0; p.update(dx, dy); } public static void main(String[] args) { new Main(); } class Man { public int x, y, w, h; public float cR, cG, cB; public Man(int x, int y) { this.x = x; this.y = y; w = 50; h = 50; Random rand = new Random(); cR = rand.nextFloat(); cG = rand.nextFloat(); cB = rand.nextFloat(); } public void draw() { glColor3f(cR, cG, cB); glRecti(x, y, x+w, y+h); } public void update(int dx, int dy) { x += dx; y += dy; } } } That is the code that I am working with. In addition, I am unsure how to compile an executable jar that is using the lwjgl library in addition to slick-util.

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  • Delayed startup of network icon (wi-fi)

    - by Michael Dy
    When my Windows 7 Starter netbook boots up and after everything is loaded, it takes about five minutes before the network icon near the clock becomes functional. When there's an available wi-fi signal (which automatically connects to my netbook as preconfigured) after the boot, my netbook seamlessly connects to it even if the network icon cannot be clicked or accessed. (The icon is shown to be loading for about five minutes.) During this time, when I go to Network and Sharing Center, it takes the same time to load. So even while the icon and the Center cannot be accessed, I can surf the Internet. When my netbook was still new, it didn't have this issue. How do I fix this?

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  • Wi-Fi connected but can't go to any site

    - by Michael Dy
    My Windows 7 laptop can connect to our Wi-Fi signal, I can sign in on Yahoo! Messenger, but I can't go to any site. I can access the Net on other devices. The issue started a few weeks ago, so I've been troubleshooting since then in vain. There's no virus, and I already used System Restore. In Wireless Network Connection Status, the received activity is greater than the sent activity. I turned off Windows Firewall and still no Net access. My ping tests: How do I fix this?

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  • How to make a character jump, both on objects and just normal jump.

    - by haxerflaxer
    Hi, I'm kind of a beginner when it comes to java programming, and I have a project in school where I'm going to create a game much like Icy Tower. And my question is, how am I going to write to make the character stand on the ground and be able to jump up on objects? Here's my code so far: Part one package Sprites; import java.awt.Image; import java.awt.event.KeyEvent; import javax.swing.ImageIcon; public class jumper { private String jump = "oka.png"; private int dx; private int dy; private int x; private int y; private Image image; public jumper() { ImageIcon ii = new ImageIcon(this.getClass().getResource(jump)); image = ii.getImage(); x = 50; y = 100; } public void move() { x += dx; y += dy; } public int getX() { return x; } public int getY() { return y; } public Image getImage() { return image; } public void keyPressed(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = -5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oki.png")); image = ii.getImage(); } if (key == KeyEvent.VK_RIGHT){ dx = 5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oka.png")); image = ii.getImage(); } if (key == KeyEvent.VK_SPACE) { dy = -5; } if (key == KeyEvent.VK_DOWN) { dy = 5; } } public void keyReleased(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = 0; } if (key == KeyEvent.VK_RIGHT){ dx = 0; } if (key == KeyEvent.VK_SPACE) { dy = 0; } if (key == KeyEvent.VK_DOWN) { dy = 0; } } } Part two package Sprites; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.JPanel; import javax.swing.Timer; public class board extends JPanel implements ActionListener { private Timer klocka; private jumper jumper; public board() { addKeyListener(new TAdapter()); setFocusable(true); setBackground(Color.WHITE); setDoubleBuffered(true); jumper = new jumper(); klocka = new Timer(5, this); klocka.start(); } public void paint(Graphics g) { super.paint(g); Graphics2D g2d = (Graphics2D)g; g2d.drawImage(jumper.getImage(), jumper.getX(), jumper.getY(), this); Toolkit.getDefaultToolkit().sync(); g.dispose(); } public void actionPerformed(ActionEvent e) { jumper.move(); repaint(); } private class TAdapter extends KeyAdapter { public void keyReleased(KeyEvent e) { jumper.keyReleased(e); } public void keyPressed(KeyEvent e) { jumper.keyPressed(e); } } } Part three package Sprites; import javax.swing.JFrame; public class RType extends JFrame { public RType() { add(new board()); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setSize(800, 600); setLocationRelativeTo(null); setTitle("R - type"); setResizable(false); setVisible(true); } public static void main(String[] args) { new RType(); } } I really appreciate all the help I can get!

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