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  • Cocos2d rotating sprite while moving with CCBezierBy

    - by marcg11
    I've done my moving actions which consists of sequences of CCBezierBy. However I would like the sprite to rotate by following the direction of the movement (like an airplane). How sould I do this with cocos2d? I've done the following to test this out. CCSprite *green = [CCSprite spriteWithFile:@"enemy_green.png"]; [green setPosition:ccp(50, 160)]; [self addChild:green]; ccBezierConfig bezier; bezier.controlPoint_1 = ccp(100, 200); bezier.controlPoint_2 = ccp(400, 200); bezier.endPosition = ccp(300,160); [green runAction:[CCAutoBezier actionWithDuration:4.0 bezier:bezier]]; In my subclass: @interface CCAutoBezier : CCBezierBy @end @implementation CCAutoBezier - (id)init { self = [super init]; if (self) { // Initialization code here. } return self; } -(void) update:(ccTime) t { CGPoint oldpos=[self.target position]; [super update:t]; CGPoint newpos=[self.target position]; float angle = atan2(newpos.y - oldpos.y, newpos.x - oldpos.x); [self.target setRotation: angle]; } @end However it rotating, but not following the path...

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  • Drawing a texture line between two vectors in XNA WP7

    - by Krav
    I want to create a simple graph maker in WP7. The goal is to draw a texture line between two vectors what the user defines with touch. I already made the rotation, and it is working, but not correctly, because it doesn't calculate the line's texture height, and because of that, there are too many overlapping textures. So it does draw the line, but too many of them. How could I calculate it correctly? Here is the code: public void DrawLine(Vector2 st,Vector2 dest,NodeUnit EdgeParent,NodeUnit EdgeChild) { float d = Vector2.Distance(st, dest); float rotate = (float)(Math.Atan2(st.Y - dest.Y, st.X - dest.X)); direction = new Vector2(((dest.X - st.X) / (float)d), (dest.Y - st.Y) / (float)d); Vector2 _pos = st; World.TheHive.Add(new LineHiveMind(linetexture, _pos, rotate, EdgeParent, EdgeChild,new List<LineUnit>())); for (int i = 0; i < d; i++) { World.TheHive.Last()._lines.Add(new LineUnit(linetexture, _pos, rotate, EdgeParent, EdgeChild)); _pos += direction; } } d is for the Distance of the st (Starting node) and dest (Destination node) rotate is for rotation direction calculates the direction between the starting and the destination node _pos is for starting position changing Thanks for any suggestions/help!

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  • Facing a character towards the mouse

    - by ratata
    I'm trying to port a simple 2d top down shooter game from C++(Allegro) to Java and i'm having problems with rotating my character. Here's the code i used in c++ if (keys[A]) RotateRight(player, degree); if (keys[D]) RotateLeft(player, degree); void RotateLeft(Player& player, float& degree) { degree += player.rotatingSpeed; if ( degree >= 360 ) degree = 0; } void RotateRight(Player& player, float& degree) { degree -= player.rotatingSpeed; if ( degree <= 0) degree = 360; } And this is what i have in render section: al_draw_rotated_bitmap(player.image, player.frameWidth / 2, player.frameHeight / 2, player.x, player.y, degree * 3.14159 / 180, 0); Instead of using A-D keys i want to use mouse this time. I've been searching since last night and came up to few sample codes however noone of them worked. For example this just made my character to circle around the map: int centerX = width / 2; int centerY = height / 2; double angle = Math.atan2(centerY - mouseY, centerX - mouseX) - Math.PI / 2; ((Graphics2D)g).rotate(angle, centerX, centerY); g.fillRect(...); // draw your rectangle Any help is much appreciated.

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  • snapping an angle to the closest cardinal direction

    - by Josh E
    I'm developing a 2D sprite-based game, and I'm finding that I'm having trouble with making the sprites rotate correctly. In a nutshell, I've got spritesheets for each of 5 directions (the other 3 come from just flipping the sprite horizontally), and I need to clamp the velocity/rotation of the sprite to one of those directions. My sprite class has a pre-computed list of radians corresponding to the cardinal directions like this: protected readonly List<float> CardinalDirections = new List<float> { MathHelper.PiOver4, MathHelper.PiOver2, MathHelper.PiOver2 + MathHelper.PiOver4, MathHelper.Pi, -MathHelper.PiOver4, -MathHelper.PiOver2, -MathHelper.PiOver2 + -MathHelper.PiOver4, -MathHelper.Pi, }; Here's the positional update code: if (velocity == Vector2.Zero) return; var rot = ((float)Math.Atan2(velocity.Y, velocity.X)); TurretRotation = SnapPositionToGrid(rot); var snappedX = (float)Math.Cos(TurretRotation); var snappedY = (float)Math.Sin(TurretRotation); var rotVector = new Vector2(snappedX, snappedY); velocity *= rotVector; //...snip private float SnapPositionToGrid(float rotationToSnap) { if (rotationToSnap == 0) return 0.0f; var targetRotation = CardinalDirections.First(x => (x - rotationToSnap >= -0.01 && x - rotationToSnap <= 0.01)); return (float)Math.Round(targetRotation, 3); } What am I doing wrong here? I know that the SnapPositionToGrid method is far from what it needs to be - the .First(..) call is on purpose so that it throws on no match, but I have no idea how I would go about accomplishing this, and unfortunately, Google hasn't helped too much either. Am I thinking about this the wrong way, or is the answer staring at me in the face?

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  • Calculating the correct particle angle in an outwards explosion

    - by Sun
    I'm creating a simple particle explosion but am stuck in finding the correct angle to rotate my particle. The effect I'm going for is similar to this: Where each particle is going outwards from the point of origin and at the correct angle. This is what I currently have: As you can see, each particle is facing the same angle, but I'm having a little difficulty figuring out the correct angle. I have the vector for the point of emission and the new vector for each particle, how can I use this to calculate the angle? Some code for reference: private Particle CreateParticle() { ... Vector2 velocity = new Vector2(2.0f * (float)(random.NextDouble() * 2 - 1), 2.0f * (float)(random.NextDouble() * 2 - 1)); direction = velocity - ParticleLocation; float angle = (float)Math.Atan2(direction.Y, direction.X); ... return new Particle(texture, position, velocity, angle, angularVelocity, color, size, ttl, EmitterLocation); } I am then using the angle created as so in my particles Draw method: spriteBatch.Draw(Texture, Position, null, Color, Angle, origin, Size, SpriteEffects.None, 0f);

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  • how to rotate a sprite using multi touch (andengine) in android?

    - by 786
    I am new to android game development. I am using andengine GLES-2. i have created sprite as a box. this box is now draggable by using this coding. it works fine. but i want multitouch on this which i want to rotate a sprite with 2 finger in that box and even it should be draggable. .... plz help someone by overwriting this code or by giving exact example of this doubt... i am trying this many days but no idea. final float centerX = (CAMERA_WIDTH - this.mBox.getWidth()) / 2; final float centerY = (CAMERA_HEIGHT - this.mBox.getHeight()) / 2; Box= new Sprite(centerX, centerY, this.mBox, this.getVertexBufferObjectManager()) { public boolean onAreaTouched(TouchEvent pSceneTouchEvent, float pTouchAreaLocalX, float pTouchAreaLocalY) { this.setPosition(pSceneTouchEvent.getX() - this.getWidth()/ 2, pSceneTouchEvent.getY() - this.getHeight() / 2); float pValueX = pSceneTouchEvent.getX(); float pValueY = CAMERA_HEIGHT-pSceneTouchEvent.getY(); float dx = pValueX - gun.getX(); float dy = pValueY - gun.getY(); double Radius = Math.atan2(dy,dx); double Angle = Radius * 360 ; Box.setRotation((float)Math.toDegrees(Angle)); return true; } thanks

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  • How to offset particles from point of origin

    - by Sun
    Hi I'm having troubles off setting particles from a point of origin. I want my particles to spread out after a certain radius from a the point of origin. For example, this is what I have right now: All particles emitted from a point of origin. What I want is this: Particles are offset from the point of origin by some amount, i.e after the circle. What is the best way to achieve this? At the moment, I have the point of origin, the position of each particle and its rotation angle. Sorry for the poor illustrations. Edit: I was mistaken, when a particle is created, I have only the point of origin. When the particle is created I am able to calculate the rotation of the particle in the update method after it has moved to a new location using atan2() method. This is how I create/manage particles: Created new particle at enemy ship death location, for every new particle which is added to the list, call Update and Draw to update its position, calculate new angle and draw it.

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  • How do I retain previously drawn graphics?

    - by Cromanium
    I've created a simple program that draws lines from a fixed point to a random point each frame. I wanted to keep each line on the screen. However, it always seems to be cleared each time it draws on the spriteBatch even without GraphicsDevice.Clear(color) being called. What seems to be the problem? protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); DrawLine(spriteBatch); spriteBatch.End(); base.Draw(gameTime); } private void DrawLine(SpriteBatch spriteBatch) { Random r = new Random(); Vector2 a = new Vector2(50, 100); Vector2 b = new Vector2(r.Next(0, 640), r.Next(0,480)); Texture2D filler= new Texture2D(GraphicsDevice, 1, 1, false, SurfaceFormat.Color); filler.SetData(new[] { Color.Black }); float length = Vector2.Distance(a, b); float angle = (float)Math.Atan2(b.Y - a.Y, b.X - a.X); spriteBatch.Draw(filler, a, null, Color.Black, angle, Vector2.Zero, new Vector2(length,10.0f), SpriteEffects.None, 0f); } What am I doing wrong?

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  • what's wrong with my lookAt and move forward code?

    - by alaslipknot
    so am still in the process of getting familiar with libGdx and one of the fun things i love to do is to make basics method for reusability on future projects, and for now am stacked on getting a Sprite rotate toward target (vector2) and then move forward based on that rotation the code am using is this : // set angle public void lookAt(Vector2 target) { float angle = (float) Math.atan2(target.y - this.position.y, target.x - this.position.x); angle = (float) (angle * (180 / Math.PI)); setAngle(angle); } // move forward public void moveForward() { this.position.x += Math.cos(getAngle())*this.speed; this.position.y += Math.sin(getAngle())*this.speed; } and this is my render method : @Override public void render(float delta) { // TODO Auto-generated method stub Gdx.gl.glClearColor(0, 0, 0.0f, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); // groupUpdate(); Vector3 mousePos = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0); camera.unproject(mousePos); ball.lookAt(new Vector2(mousePos.x, mousePos.y)); // if (Gdx.input.isTouched()) { ball.moveForward(); } batch.begin(); batch.draw(ball.getSprite(), ball.getPos().x, ball.getPos().y, ball .getSprite().getOriginX(), ball.getSprite().getOriginY(), ball .getSprite().getWidth(), ball.getSprite().getHeight(), .5f, .5f, ball.getAngle()); batch.end(); } the goal is to make the ball always look at the mouse cursor, and then move forward when i click, am also using this camera : // create the camera and the SpriteBatch camera = new OrthographicCamera(); camera.setToOrtho(false, 800, 480); aaaand the result was so creepy lol Thank you

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  • get rotation direction of UIView on touchesMoved

    - by mlecho
    this may sound funny, but i spent hours trying to recreate a knob with a realistic rotation using UIView and some trig. I achieved the goal, but now i can not figure out how to know if the knob is rotating left or right. The most pertinent part of the math is here: - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint pt = [touch locationInView:self]; float dx = pt.x - iv.center.x; float dy = pt.y - iv.center.y; float ang = atan2(dy,dx); //do the rotation if (deltaAngle == 0.0) { deltaAngle = ang; initialTransform = iv.transform; }else { float angleDif = deltaAngle - ang; CGAffineTransform newTrans = CGAffineTransformRotate(initialTransform, -angleDif); iv.transform = newTrans; currentValue = [self goodDegrees:radiansToDegrees(angleDif)]; } } ideally, i could leverage a numeric value to tell me if the rotation is positive or negative.

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  • Rotation towards an object in 3d space

    - by retoucher
    hello, i have two coordinates on a 2d plane in 3d space, and am trying to rotate one coordinate (a vector) to face the other coordinate. my vertical axis is the y-axis, so if both of the coordinates are located flat on the 2d plane, they would both have a y-axis of 0, and their x and z coordinates determine their position length/width-wise on the plane. right now, i'm calculating the angle like so (language agnostic): angle = atan2(z2-z1,x2-x1); and am rotating/translating in space like so: pushMatrix(); rotateY(angle); popMatrix(); this doesn't seem to be working though. are my calculations/process correct?

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  • How to get Distance Kilometer in android?

    - by user1787493
    i am very new to Google maps i want calculate the distance between two places in android .for that i get the two places lat and lag positions for that i write the following code: private double getDistance(double lat1, double lat2, double lon1, double lon2) { double dLat = Math.toRadians(lat2 - lat1); double dLon = Math.toRadians(lon2 - lon1); double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2) * Math.sin(dLon / 2); double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)); double temp = 6371 * c; temp=temp*0.621; return temp; } the above code cant give the accurate distance between two places .what is the another way to find distance please give me any suggestions thanks in advance....

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  • Relative Position in PHP between 2 points (Lat/Long)

    - by Brian H
    I have a database of airports with Latitude and Longitude for each point. I want to run a PHP script to find all airports that are nearby a given airport, with their distance and relative direction. I.e. for Airport KLDJ (40-37-02.810N 074-14-40.539W) Airport Nearby KJFK - John F Kennedy Airport (21.2 nm NE) (40-38-23.104N 073-46-44.132W) I have used code from http://www.movable-type.co.uk/scripts/latlong.html to find distance, and tried to use it to find bearing, which might not be right. //BEARING RHUMB LINE $phi = log(tan($lat2/2+pi/4)/tan($lat1/2+pi/4)); $distance['bearing'] = (rad2deg(atan2($theta, $phi)) +180) % 360; I basically want to run all points through this script and find the distance, which I have already, but then the direction. (i.e. N, S, W, E, NW, SW, NE, SE)

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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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  • calculating a gps coordinate given a point, bearing and distance

    - by user530509
    Hello, I have a problem which draws my back in some project for some time now. Im basically looking to trap a polygon using x,y points drawn by some script ive written. lat1,lon1 are the center gps cords of the polygon and im looking for its surrounding polygon. here is a part of my code in python: def getcords(lat1,lon1,dr,bearing): lat2=asin(sin(lat1)*cos(dr)+cos(lat1)*sin(dr)*cos(bearing)) lon2=lon1+atan2(sin(bearing)*sin(dr)*cos(lat1),cos(dr)-sin(lat1)*sin(lat2)) return [lat2,lon2] my input goes like this: lat1,lon1 - are given in decimal degrees. -dr is the angular computed by dividing the distance in miles by the earth's -raiuds(=3958.82) -bearing between 0-360 degrees. however for the input getcorsds1(42.189275,-76.85823,0.5/3958.82,30) i get [-1.3485899508698462, -76.8576637627568], however [42.2516666666667,-76.8097222222222] is the right answer. as for the angular distance i calculate it simply by dividing the distance in miles by the earth's raiuds(=3958.82). anybody?

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  • Using Sandy 3D AS3, fill the viewport (exact fit) with multiple 3D objects.

    - by Andrew Mullins
    I'm stitching together an image using multiple instances of the sandy.primitive.Box. Each box is 96x91 while the viewport is 960x273 which should make for an exact fit if I layout the boxes in a perfect grid of 10x3. However, I can't seem to get the exact camera fieldOfView. I've tried a couple formulas (one for adjusting the "focal length" and one for adjusting the fov, directly). Both of these formulas produce a fov angle that is too narrow. // focal length (stage.stageHeight/2) / Math.tan(cam.fov / 2 * Math.PI / 180) // field of view 2 * Math.atan2( (stage.stageHeight/2), -cam.z ) * (180 / Math.PI) Another question about the same project: I need to adjust the perspective of each cube so that the image appears to be in 2D space (flat)... Any ideas on the best method for calculating such a "correction"?

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  • Moving a Ball on iPhone

    - by Chandan Shetty SP
    I am using below formula to move the ball circular, where accelX and accelY are the values from accelerometer, it is working fine. But the problem in this code is mRadius(I fixed its value to 50), i need to change mRadius according to accelerometer values and also i need bouncing effect when it touches other circles please send your answers ASAP... I am waiting. float degrees = -atan2(accelX, accelY) * 180 / 3.14159; int x = cCentrePoint.x + mRadius * cos(degreesToRadians(degrees)); int y = cCentrePoint.y + mRadius * sin(degreesToRadians(degrees)); Here is the snap of the game i want to develop. http://iphront.com/wp-content/uploads/2009/12/bdece528ea334033.jpg.jpg

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  • signed angle between two 3d vectors with same origin within the same plane? recipe?

    - by Advanced Customer
    Was looking through the web for an answer but it seems like there is no clear recipe for it. What I need is a signed angle of rotation between two vectors Va and Vb lying within the same 3D plane and having the same origin knowing that: the plane contatining both vectors is an arbitrary and is not parallel to XY or any other of cardinal planes Vn - is a plane normal both vectors along with the normal have the same origin O = { 0, 0, 0 } Va - is a reference for measuring the left handed rotation at Vn The angle should be measured in such a way so if the plane would be XY plane the Va would stand for X axis unit vector of it. I guess I should perform a kind of coordinate space transformation by using the Va as the X-axis and the cross product of Vb and Vn as the Y-axis and then just using some 2d method like with atan2() or something. Any ideas? Formulas?

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  • Calculating the angle between two points

    - by kingrichard2005
    I'm currently developing a simple 2D game for Android. I have a stationary object that's situated in the center of the screen and I'm trying to get that object to rotate and point to the area on the screen that the user touches. I have the constant coordinates that represent the center of the screen and I can get the coordinates of the point that the user taps on. I'm using the formula outlined in this forum: How to get angle between two points? -It says as follows "If you want the the angle between the line defined by these two points and the horizontal axis: double angle = atan2(y2 - y1, x2 - x1) * 180 / PI;". -I implemented this, but I think the fact the I'm working in screen coordinates is causing a miscalculation, since the Y-coordinate is reversed. I'm not sure if this is the right way to go about it, any other thoughts or suggestions are appreciated.

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  • Why does my sprite glitch when moving? [closed]

    - by rphello101
    Using Slick 2D/Java, I'm using the mouse to rotate a sprite and WASD to move it (A and D are used to strafe). I finally got the directional keys and rotation to work in sync, but I'm having problems with sporadic movement. It seems that the move speed is not always set to the value I have it at. Sometimes the sprite with just shoot across the screen. Furthermore, it seems that at 0 degrees, when the left key is pressed, the sprite moves backwards, not to the left. There also seems to be quite a bit of glitching when two keys are pressed, like left and up. Anyone see anything obvious? Here is the rotational code: int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x+sprite.image.getWidth()/2; int pY = sprite.y+sprite.image.getHeight()/2; double mAng; if(mX!=pX){ mAng = Math.toDegrees(Math.atan2(mY - pY, mX - pX)); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=90; else mAng=270; } sprite.angle = mAng; sprite.image.setRotation((float) mAng); Movement code: Input input = gc.getInput(); Vector2f direction = new Vector2f(); Vector2f velocity = new Vector2f(); Vector2f left; Vector2f right; direction.x = (float) Math.cos(Math.toRadians(sprite.angle)); direction.y = (float) Math.sin(Math.toRadians(sprite.angle)); if(direction.length()>0) direction = direction.normalise(); left = new Vector2f(-direction.y, direction.x); right = new Vector2f(direction.y, -direction.x); velocity.x = (float) (direction.x * sprite.moveSpeed); velocity.y = (float) (direction.y * sprite.moveSpeed); if(input.isKeyDown(sprite.up)){ sprite.x += velocity.x*delta; sprite.y += velocity.y*delta; }if (input.isKeyDown(sprite.down)){ sprite.x -= velocity.x*delta; sprite.y -= velocity.y*delta; }if (input.isKeyDown(sprite.left)){ sprite.x += left.x * sprite.moveSpeed * delta; sprite.y += left.y * sprite.moveSpeed * delta; }if (input.isKeyDown(sprite.right)){ sprite.x += right.x * sprite.moveSpeed * delta; sprite.y += right.y * sprite.moveSpeed * delta; }

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  • determine collision angle on a rotating body

    - by jorb
    update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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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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  • Collision between sprites in game programming?

    - by Lyn Maxino
    I've since just started coding for an android game using eclipse. I've read Beginning Android Game Programming and various other e-books. Recently, I've encountered a problem with collision between sprites. I've used this code template for my program. package com.project.CAI_test; import java.util.Random; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Rect; public class Sprite { // direction = 0 up, 1 left, 2 down, 3 right, // animation = 3 back, 1 left, 0 front, 2 right int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 }; private static final int BMP_ROWS = 4; private static final int BMP_COLUMNS = 3; private static final int MAX_SPEED = 5; private GameView gameView; private Bitmap bmp; private int x = 0; private int y = 0; private int xSpeed; private int ySpeed; private int currentFrame = 0; private int width; private int height; public Sprite(GameView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMP_COLUMNS; this.height = bmp.getHeight() / BMP_ROWS; this.gameView = gameView; this.bmp = bmp; Random rnd = new Random(); x = rnd.nextInt(gameView.getWidth() - width); y = rnd.nextInt(gameView.getHeight() - height); xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; } private void update() { if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) { xSpeed = -xSpeed; } x = x + xSpeed; if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) { ySpeed = -ySpeed; } y = y + ySpeed; currentFrame = ++currentFrame % BMP_COLUMNS; } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = getAnimationRow() * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } private int getAnimationRow() { double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2); int direction = (int) Math.round(dirDouble) % BMP_ROWS; return DIRECTION_TO_ANIMATION_MAP[direction]; } public boolean isCollition(float x2, float y2) { return x2 > x && x2 < x + width && y2 > y && y2 < y + height; } } The above code only detects collision between the generated sprites and the surface border. What I want to achieve is a collision detection that is controlled by the update function without having to change much of the coding. Probably several lines placed in the update() function. Tnx for any comment/suggestion.

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  • Joystick example problem for android 2D

    - by iQue
    I've searched all over the web for an answer to this, and there are simular topics but nothing works for me, and I have no Idea why. I just want to move my sprite using a joystick, since I'm useless at math when it comes to angles etc I used an example, Ill post the code here: public float initx = 50; //og 425; public float inity = 300; //og 267; public Point _touchingPoint = new Point(50, 300); //og(425, 267); public Point _pointerPosition = new Point(100, 170); private Boolean _dragging = false; private MotionEvent lastEvent; @Override public boolean onTouchEvent(MotionEvent event) { if (event == null && lastEvent == null) { return _dragging; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } // drag drop if (event.getAction() == MotionEvent.ACTION_DOWN) { _dragging = true; } else if (event.getAction() == MotionEvent.ACTION_UP) { _dragging = false; } if (_dragging) { // get the pos _touchingPoint.x = (int) event.getX(); _touchingPoint.y = (int) event.getY(); // bound to a box if (_touchingPoint.x < 25) { _touchingPoint.x = 25; //og 400 } if (_touchingPoint.x > 75) { _touchingPoint.x = 75; //og 450 } if (_touchingPoint.y < 275) { _touchingPoint.y = 275; //og 240 } if (_touchingPoint.y > 325) { _touchingPoint.y = 325; //og 290 } // get the angle double angle = Math.atan2(_touchingPoint.y - inity, _touchingPoint.x - initx) / (Math.PI / 180); // Move the beetle in proportion to how far // the joystick is dragged from its center _pointerPosition.y += Math.sin(angle * (Math.PI / 180)) * (_touchingPoint.x / 70); _pointerPosition.x += Math.cos(angle * (Math.PI / 180)) * (_touchingPoint.x / 70); // stop the sprite from goin thru if (_pointerPosition.x + happy.getWidth() >= getWidth()) { _pointerPosition.x = getWidth() - happy.getWidth(); } if (_pointerPosition.x < 0) { _pointerPosition.x = 0; } if (_pointerPosition.y + happy.getHeight() >= getHeight()) { _pointerPosition.y = getHeight() - happy.getHeight(); } if (_pointerPosition.y < 0) { _pointerPosition.y = 0; } } public void render(Canvas canvas) { canvas.drawColor(Color.BLUE); canvas.drawBitmap(joystick.get_joystickBg(), initx-45, inity-45, null); canvas.drawBitmap(happy, _pointerPosition.x, _pointerPosition.y, null); canvas.drawBitmap(joystick.get_joystick(), _touchingPoint.x - 26, _touchingPoint.y - 26, null); } public void update() { this.onTouchEvent(null); } og= original position. as you can see Im trying to move the joystick, but when I do it stops working correctly, I mean it still works like a joystick but the sprite dosnt move accordingly, if I for example push the joystick down, the sprite moves up, and if I push it up it moves left. can anyone PLEASE help me, I've been stuck here for sooo long and its really frustrating.

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  • rotate player based off of joystick

    - by pengume
    Hey everyone I have this game that i am making in android and I have a touch screen joystick that moves the player around based on the joysticks position. I cant figure out how to also get the player to rotate at the same angle of the joystick. so when the joystick is to the left the players bitmap is rotated to the left as well. Maybe someone here has some sample code I could look at here is the joysticks class that I am using. `public class GameControls implements OnTouchListener { public float initx = DroidzActivity.screenWidth - 45; //255; // 320 og 425 public float inity = DroidzActivity.screenHeight - 45;//425; // 480 og 267 public Point _touchingPoint = new Point( DroidzActivity.screenWidth - 45, DroidzActivity.screenHeight - 45); public Point _pointerPosition = new Point(DroidzActivity.screenWidth - 100, DroidzActivity.screenHeight - 100); // ogx 220 ogy 150 private Boolean _dragging = false; private boolean attackMode = false; @Override public boolean onTouch(View v, MotionEvent event) { update(event); return true; } private MotionEvent lastEvent; public boolean ControlDragged; private static double angle; public void update(MotionEvent event) { if (event == null && lastEvent == null) { return; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } // drag drop if (event.getAction() == MotionEvent.ACTION_DOWN) { if ((int) event.getX() > 0 && (int) event.getX() < 50 && (int) event.getY() > DroidzActivity.screenHeight - 160 && (int) event.getY() < DroidzActivity.screenHeight - 0) { setAttackMode(true); } else { _dragging = true; } } else if (event.getAction() == MotionEvent.ACTION_UP) { if(isAttackMode()){ setAttackMode(false); } _dragging = false; } if (_dragging) { ControlDragged = true; // get the pos _touchingPoint.x = (int) event.getX(); _touchingPoint.y = (int) event.getY(); // Log.d("GameControls", "x = " + _touchingPoint.x + " y = " //+ _touchingPoint.y); // bound to a box if (_touchingPoint.x < DroidzActivity.screenWidth - 75) { // og 400 _touchingPoint.x = DroidzActivity.screenWidth - 75; } if (_touchingPoint.x > DroidzActivity.screenWidth - 15) {// og 450 _touchingPoint.x = DroidzActivity.screenWidth - 15; } if (_touchingPoint.y < DroidzActivity.screenHeight - 75) {// og 240 _touchingPoint.y = DroidzActivity.screenHeight - 75; } if (_touchingPoint.y > DroidzActivity.screenHeight - 15) {// og 290 _touchingPoint.y = DroidzActivity.screenHeight - 15; } // get the angle setAngle(Math.atan2(_touchingPoint.y - inity, _touchingPoint.x - initx) / (Math.PI / 180)); // Move the ninja in proportion to how far // the joystick is dragged from its center _pointerPosition.y += Math.sin(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // og 180 70 _pointerPosition.x += Math.cos(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // make the pointer go thru if (_pointerPosition.x > DroidzActivity.screenWidth) { _pointerPosition.x = 0; } if (_pointerPosition.x < 0) { _pointerPosition.x = DroidzActivity.screenWidth; } if (_pointerPosition.y > DroidzActivity.screenHeight) { _pointerPosition.y = 0; } if (_pointerPosition.y < 0) { _pointerPosition.y = DroidzActivity.screenHeight; } } else if (!_dragging) { ControlDragged = false; // Snap back to center when the joystick is released _touchingPoint.x = (int) initx; _touchingPoint.y = (int) inity; // shaft.alpha = 0; } } public void setAttackMode(boolean attackMode) { this.attackMode = attackMode; } public boolean isAttackMode() { return attackMode; } public void setAngle(double angle) { this.angle = angle; } public static double getAngle() { return angle; } }` I should also note that the player has animations based on when he is moving or attacking.

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