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  • How to properly render a Frame Buffer to the BackBuffer in Stage3D / AGAL

    - by bigp
    After doing a render pass with RenderToTarget (RTT), how do you properly render that texture buffer to the screen while maintaining original scale / proportions so it doesn't stretch or lose quality? Can an AGAL VertexShader & FragmentShader be written so it's adaptable to any Texture size and Viewport dimensions? I find I'm getting some "blocky" effects in some of my first attempts at "ping-ponging" between two Texture buffers (to create trailing effects). Perhaps I'm not using the UVs correctly between the rendering-to-target and/or the backbuffer? Is there a simpler way just to "splash" the texture on the backbuffer, or is a Quad absolutely necessary (4 vertices, 2 triangles)? If it needs the Quad, should the Texture buffer be fully drawn (0.0 to 1.0 for vertical and horizontal UVs), or only a percentage of it should, like the example below? Texture Buffer U: 0.0 to viewport.width/texturebuffer.width; Texture Buffer V: 0.0 to viewport.height/texturebuffer.height; Thanks!

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  • A* Jump Point Search - how does pruning really work?

    - by DeadMG
    I've come across Jump Point Search, and it seems pretty sweet to me. However, I'm unsure as to how their pruning rules actually work. More specifically, in Figure 1, it states that we can immediately prune all grey neighbours as these can be reached optimally from the parent of x without ever going through node x However, this seems somewhat at odds. In the second image, node 5 could be reached by first going through node 7 and skipping x entirely through a symmetrical path- that is, 6 -> x -> 5 seems to be symmetrical to 6 -> 7 -> 5. This would be the same as how node 3 can be reached without going through x in the first image. As such, I don't understand how these two images are not entirely equivalent, and not just rotated versions of each other. Secondly, I'd like to understand how this algorithm could be generalized to a three-dimensional search volume.

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  • How do I detect multiple sprite collisions when there are >10 sprites?

    - by yao jiang
    I making a small program to animate the astar algorithm. If you look at the image, there are lots of yellow cars moving around. Those can collide at any moment, could be just one or all of them could just stupidly crash into each other. How do I detect all of those collisions? How do I find out which specific car has crash into which other car? I understand that pygame has collision function, but it only detects one collision at a time and I'd have to specify which sprites. Right now I am just trying to iterate through each sprite to see if there is collision: for car1 in carlist: for car2 in carlist: collide(car1, car2); This can't be the proper way to do it, if the car list goes to a huge number, a double loop will be too slow.

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  • xna orbit camera troubles

    - by user17753
    I have a Model named cube to which I load in LoadContent(): cube = Content.Load<Model>("untitled");. In the Draw Method I call DrawModel: private void DrawModel(Model m, Matrix world) { foreach (ModelMesh mesh in m.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.View = camera.View; effect.Projection = camera.Projection; effect.World = world; } mesh.Draw(); } } camera is of the Camera type, a class I've setup. Right now it is instantiated in the initialization section with the graphics aspect ratio and the translation (world) vector of the model, and the Draw loop calls the camera.UpdateCamera(); before drawing the models. class Camera { #region Fields private Matrix view; // View Matrix for Camera private Matrix projection; // Projection Matrix for Camera private Vector3 position; // Position of Camera private Vector3 target; // Point camera is "aimed" at private float aspectRatio; //Aspect Ratio for projection private float speed; //Speed of camera private Vector3 camup = Vector3.Up; #endregion #region Accessors /// <summary> /// View Matrix of the Camera -- Read Only /// </summary> public Matrix View { get { return view; } } /// <summary> /// Projection Matrix of the Camera -- Read Only /// </summary> public Matrix Projection { get { return projection; } } #endregion /// <summary> /// Creates a new Camera. /// </summary> /// <param name="AspectRatio">Aspect Ratio to use for the projection.</param> /// <param name="Position">Target coord to aim camera at.</param> public Camera(float AspectRatio, Vector3 Target) { target = Target; aspectRatio = AspectRatio; ResetCamera(); } private void Rotate(Vector3 Axis, float Amount) { position = Vector3.Transform(position - target, Matrix.CreateFromAxisAngle(Axis, Amount)) + target; } /// <summary> /// Resets Default Values of the Camera /// </summary> private void ResetCamera() { speed = 0.05f; position = target + new Vector3(0f, 20f, 20f); projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspectRatio, 0.5f, 100f); CalculateViewMatrix(); } /// <summary> /// Updates the Camera. Should be first thing done in Draw loop /// </summary> public void UpdateCamera() { Rotate(Vector3.Right, speed); CalculateViewMatrix(); } /// <summary> /// Calculates the View Matrix for the camera /// </summary> private void CalculateViewMatrix() { view = Matrix.CreateLookAt(position,target, camup); } I'm trying to create the camera so that it can orbit the center of the model. For a test I am calling Rotate(Vector3.Right, speed); but it rotates almost right but gets to a point where it "flips." If I rotate along a different axis Rotate(Vector3.Up, speed); everything seems OK in that direction. So I guess, can someone tell me what I'm not accounting for in the above code I wrote? Or point me to an example of an orbiting camera that can be fixed on an arbitrary point?

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  • GLSL Bokeh using Quads and Textures

    - by Notoriousaur
    I'm trying to create a depth of field effect with bokeh sprites in GLSL. Specifically, what i would like to do is, for each pixel: See if the pixel is out of the focal range If it is, draw a quad and apply a texture to provide a bokeh sprite. This kind of implementation is seen in the Unreal Engine and by Matt Pettineo, however, both implementations are in DX11 and I'm using OpenGL. I'm a bit stuck on the drawing a quad and applying a texture bit. Does anyone know how I can do this, or provide any relevant links as to how I can do this? Thanks

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  • I am looking for an graduation project idea for bacelor of computer engineering [closed]

    - by project idea
    I am interested in computer graphics and I have developed many hobby projects, mostly 2D and 3D games/scenes in directX and openGL, But for a grad project, proffesors wont allow games. I browsed many similar questions here and I am convinced project should be something I am really interested in as I will give considerable time to it. But apart from games I am not able to decide on the topic. I am also open to ideas on social apps and android.

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  • How to create array with unique sprites? in cocos2d iphone

    - by prakash s
    I write the code like this. This displays only one sprite (red colour bubble) with number of times and moving down, but actually I want to display different sprites (different colour bubble) every time and moving down. I also add no of .png images in resource folder of my project. Here I used only 3.png, but I need to display all *.png images (different colour bubbles) in my project but I don't know how to get this. Please help me Thank you. Here is the code: -(void)addTarget { CCSprite *target = [CCSprite spriteWithFile:@"3.png" rect:CGRectMake(0, 0, 256, 256)]; CGSize winSize = [[CCDirector sharedDirector] winSize]; int minY = target.contentSize.height/2; int maxY = winSize.height - target.contentSize.height/2; int rangeY = maxY - minY; int actualY = (arc4random() % rangeY) + minY; // Create the target slightly off-screen along the right edge, // and along a random position along the Y axis as calculated above target.position = ccp(winSize.width + (target.contentSize.width/2), actualY); [self addChild:target]; // Determine speed of the target int minDuration = 4.0; int maxDuration = 12.0; int rangeDuration = maxDuration - minDuration; int actualDuration = (arc4random() % rangeDuration) + minDuration; // Create the actions id actionMove = [CCMoveTo actionWithDuration:actualDuration position:ccp(-target.contentSize.width/2,actualY)]; id actionMoveDone = [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)]; [target runAction:[CCSequence actions:actionMove, actionMoveDone, nil]]; // Add to targets array target.tag = 2; [_targets addObject:target]; } -(void)gameLogic:(ccTime)dt { [self addTarget]; } -(id) init { if( (self=[super initWithColor:ccc4(255,255,255,255)] )) { // Enable touch events self.isTouchEnabled = YES; // Initialize arrays _targets = [[NSMutableArray alloc] init]; _projectiles = [[NSMutableArray alloc] init]; // Get the dimensions of the window for calculation purposes CGSize winSize = [[CCDirector sharedDirector] winSize]; [self schedule:@selector(gameLogic:) interval:1.0]; [self schedule:@selector(update:)]; } return self; } - (void)update:(ccTime)dt { NSMutableArray *projectilesToDelete = [[NSMutableArray alloc] init]; for (CCSprite *projectile in _projectiles) { CGRect projectileRect = CGRectMake(projectile.position.x - (projectile.contentSize.width/2), projectile.position.y - (projectile.contentSize.height/2), projectile.contentSize.width, projectile.contentSize.height); NSMutableArray *targetsToDelete = [[NSMutableArray alloc] init]; for (CCSprite *target in _targets) { CGRect targetRect = CGRectMake(target.position.x - (target.contentSize.width/2), target.position.y - (target.contentSize.height/2), target.contentSize.width, target.contentSize.height); if (CGRectIntersectsRect(projectileRect, targetRect)) { [targetsToDelete addObject:target]; } } for (CCSprite *target in targetsToDelete) { [_targets removeObject:target]; [self removeChild:target cleanup:YES]; _projectilesDestroyed++; if (_projectilesDestroyed > 30) { //GameOverScene *gameOverScene = [GameOverScene node]; // [gameOverScene.layer.label setString:@"You Win!"]; // [[CCDirector sharedDirector] replaceScene:gameOverScene]; } } if (targetsToDelete.count > 0) { [projectilesToDelete addObject:projectile]; } [targetsToDelete release]; } for (CCSprite *projectile in projectilesToDelete) { [_projectiles removeObject:projectile]; [self removeChild:projectile cleanup:YES]; } [projectilesToDelete release]; }

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  • Create dynamic buffer SharpDX

    - by fedab
    I want to set a buffer that is updated every frame but can't figure it out, what i have to do. The only working thing i have is this: mdexcription = new BufferDescription(Matrix.SizeInBytes * Matrices.Length, ResourceUsage.Dynamic, BindFlags.VertexBuffer, CpuAccessFlags.Write, ResourceOptionFlags.None, 0); instanceBuffer = SharpDX.Direct3D11.Buffer.Create(Device, Matrices, mdexcription); vBB = new VertexBufferBinding(instanceBuffer, Matrix.SizeInBytes, 0); DeviceContext.InputAssembler.SetVertexBuffers(1, vBB); Draw: //Change Matrices (Matrix[]) every frame... instanceBuffer.Dispose(); instanceBuffer = SharpDX.Direct3D11.Buffer.Create(Device, Matrices, mdexcription); vBB = new VertexBufferBinding(instanceBuffer, Matrix.SizeInBytes, 0); DeviceContext.InputAssembler.SetVertexBuffers(1, vBB); I guess Dispose() and creating a new buffer is slow and can be done much faster. I've read about DataStream but i do not know, how to set this up properly. What steps do i have to do to set up a DataStream to achieve fast every-frame update?

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  • Transform between two 3d cartesian coordinate systems

    - by Pris
    I'd like to know how to get the rotation matrix for the transformation from one cartesian coordinate system (X,Y,Z) to another one (X',Y',Z'). Both systems are defined with three orthogonal vectors as one would expect. No scaling or translation occurs. I'm using OpenSceneGraph and it offers a Matrix convenience class, if it makes finding the matrix easier: http://www.openscenegraph.org/documentation/OpenSceneGraphReferenceDocs/a00403.html.

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  • Parabolic throw with set Height and range (libgdx)

    - by Tauboga
    Currently i'm working on a minigame for android where you have a rotating ball in the center of the display which jumps when touched in the direction of his current angle. I'm simply using a gravity vector and a velocity vector in this way: positionBall = positionBall.add(velocity); velocity = velocity.add(gravity); and velocity.x = (float) Math.cos(angle) * 12; /* 12 to amplify the velocity */ velocity.y = (float) Math.sin(angle) * 15; /* 15 to amplify the velocity */ That works fine. Here comes the problem: I want to make the jump look the same on all possible resolutions. The velocity needs to be scaled in a way that when the ball is thrown straight upwards it will touch the upper display border. When thrown directly left or right the range shall be exactly long enough to touch the left/right display border. Which formula(s) do I need to use and how to implement them correctly? Thanks in advance!

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  • Orthographic Projection Issue

    - by Nick
    I have a problem with my Ortho Matrix. The engine uses the perspective projection fine but for some reason the Ortho matrix is messed up. (See screenshots below). Can anyone understand what is happening here? At the min I am taking the Projection matrix * Transform (Translate, rotate, scale) and passing to the Vertex shader to multiply the Vertices by it. VIDEO Shows the same scene, rotating on the Y axis. http://youtu.be/2feiZAIM9Y0 void Matrix4f::InitOrthoProjTransform(float left, float right, float top, float bottom, float zNear, float zFar) { m[0][0] = 2 / (right - left); m[0][1] = 0; m[0][2] = 0; m[0][3] = 0; m[1][0] = 0; m[1][1] = 2 / (top - bottom); m[1][2] = 0; m[1][3] = 0; m[2][0] = 0; m[2][1] = 0; m[2][2] = -1 / (zFar - zNear); m[2][3] = 0; m[3][0] = -(right + left) / (right - left); m[3][1] = -(top + bottom) / (top - bottom); m[3][2] = -zNear / (zFar - zNear); m[3][3] = 1; } This is what happens with Ortho Matrix: This is the Perspective Matrix:

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  • Bohemia Interactive's bio2s format

    - by Jaime Soto
    Does anyone have specifications for the bio2s scripting language from Bohemia Interactive? They develop Operation Flashpoint, Armed Assault (ArmA), and Virtual Battlespace. These scripts are sometimes called O2 or Oxygen scripts and are used in their terrain and modeling tools. Oxygen is Bohemia Interactive's modeling tool. I found additional examples of the format in this VBS2 tutorial and this ArmA forum thread. EDIT: I clarified the purpose of the bio2s format and provided some links to examples.

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  • Cannot convert parameter 1 from 'short *' to 'int *' [closed]

    - by Torben Carrington
    I'm trying to learn pointers and since I recently learned that short int takes up less memory [2 bytes as apposed to the long int's memory usage of 4 which is the default for int] I wanted to create a pointer that uses the memory address of a short integer. I'm following a tutorial in my book about Pointers and it's using the Swap function. The problem is I receive this error the moment I change everything from int to short int: error C2664: 'Swap' : cannot convert parameter 1 from 'short *' to 'int *' 1 Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast Since my code is so small here is the whole thing: void Swap(short int *sipX, short int *sipY) { short int siTemp = *sipX; *sipX = *sipY; *sipY = siTemp; } int main() { short int siBig = 100; short int siSmall = 1; std::cout << "Pre-Swap: " << siBig << " " << siSmall << std::endl; Swap(&siBig, &siSmall); std::cout << "Post-Swap: " << siBig << " " << siSmall << std::endl; return 0; }

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  • Arbitrary Rotation about a Sphere

    - by Der
    I'm coding a mechanic which allows a user to move around the surface of a sphere. The position on the sphere is currently stored as theta and phi, where theta is the angle between the z-axis and the xz projection of the current position (i.e. rotation about the y axis), and phi is the angle from the y-axis to the position. I explained that poorly, but it is essentially theta = yaw, phi = pitch Vector3 position = new Vector3(0,0,1); position.X = (float)Math.Sin(phi) * (float)Math.Sin(theta); position.Y = (float)Math.Sin(phi) * (float)Math.Cos(theta); position.Z = (float)Math.Cos(phi); position *= r; I believe this is accurate, however I could be wrong. I need to be able to move in an arbitrary pseudo two dimensional direction around the surface of a sphere at the origin of world space with radius r. For example, holding W should move around the sphere in an upwards direction relative to the orientation of the player. I believe I should be using a Quaternion to represent the position/orientation on the sphere, but I can't think of the correct way of doing it. Spherical geometry is not my strong suit. Essentially, I need to fill the following block: public void Move(Direction dir) { switch (dir) { case Direction.Left: // update quaternion to rotate left break; case Direction.Right: // update quaternion to rotate right break; case Direction.Up: // update quaternion to rotate upward break; case Direction.Down: // update quaternion to rotate downward break; } }

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  • Matrix rotation of a rectangle to "face" a given point in 2d

    - by justin.m.chase
    Suppose you have a rectangle centered at point (0, 0) and now I want to rotate it such that it is facing the point (100, 100), how would I do this purely with matrix math? To give some more specifics I am using javascript and canvas and I may have something like this: var position = {x : 0, y: 0 }; var destination = { x : 100, y: 100 }; var transform = Matrix.identity(); this.update = function(state) { // update transform to rotate to face destination }; this.draw = function(ctx) { ctx.save(); ctx.transform(transform); // a helper that just calls setTransform() ctx.beginPath(); ctx.rect(-5, -5, 10, 10); ctx.fillStyle = 'Blue'; ctx.fill(); ctx.lineWidth = 2; ctx.stroke(); ctx.restore(); } Feel free to assume any matrix function you need is available.

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  • Understanding normal maps on terrain

    - by JohnB
    I'm having trouble understanding some of the math behind normal map textures even though I've got it to work using borrowed code, I want to understand it. I have a terrain based on a heightmap. I'm generating a mesh of triangles at load time and rendering that mesh. Now for each vertex I need to calculate a normal, a tangent, and a bitangent. My understanding is as follows, have I got this right? normal is a unit vector facing outwards from the surface of the triangle. For a vertex I take the average of the normals of the triangles using that vertex. tangent is a unit vector in the direction of the 'u' coordinates of the texture map. As my texture u,v coordinates follow the x and y coordinates of the terrain, then my understanding is that this vector is simply the vector along the surface in the x direction. So should be able to calculate this as simply the difference between vertices in the x direction to get a vector, (and normalize it). bitangent is a unit vector in the direction of the 'v' coordinates of the texture map. As my texture u,v coordinates follow the x and y coordinates of the terrain, then my understanding is that this vector is simply the vector along the surface in the y direction. So should be able to calculate this as simply the difference between vertices in the y direction to get a vector, (and normalize it). However the code I have borrowed seems much more complicated than this and takes into account the actual values of u, and v at each vertex which I don't understand the need for as they increase in exactly the same direction as x, and y. I implemented what I thought from above, and it simply doesn't work, the normals are clearly not working for lighting. Have I misunderstood something? Or can someone explain to me the physical meaning of the tangent and bitangent vectors when applied to a mesh generated from a hightmap like this, when u and v texture coordinates map along the x and y directions. Thanks for any help understanding this.

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  • 3DS Max exporting too many vertexes for model

    - by Juan Pablo
    I have a sample model of a cube and a buddha downloaded from internet in 3ds format which I can load correctly into my program and view them without problem, but wanted to try and create my own model. I created a simple box mesh in 3ds max, and exported it as .3ds (Converted to mesh - export as .3ds) When inspecting the .3ds file with a hex viewer, I was expecting to see 8 vertexes and 12 faces declared (as the model I downloaded from internet). But what i found was that it listed 26 vertexes, and 12 faces! And when I try to load that file with my .3ds viewer, my parser isn't detecting the face block (0x4120), which is strange because it worked for other objects downloaded from internet. Do I have to set any special property in order to export a 3ds file with minimum vertexes and a vertex-index list?

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  • Question about Target parameter of Matrix.CreateLookAt

    - by manning18
    I have a newbie question that's causing me a little bit of confusion when experimenting with cameras and reading other peoples implementations - does this parameter represent a point or a vector? In some examples I've seen people treat it like a specific point they are looking at (eg a position in the world), other times I see people caching the orientation of the camera in a rotation matrix and simply using the Matrix.Forward property as the "target", and other times it's a vector that's the result of targetPos - camPos and also I saw a camPos + orientation.Forward I was also just playing around with hard-coded target positions with same direction eg 1 to 10000 with no discernible difference in what I saw in the scene. Is the "Target" parameter actually a position or a direction (irrespective of magnitude)? Are there any subtle differences in behaviors, common mistakes or gotchas that are associated with what values you provide, or HOW you provide this paramter? Are all the methods I mentioned above equivalent? (sorry, I've only recently started and my math is still catching up)

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  • Rotation of bitmap using a frame by frame animation

    - by pengume
    Hey every one I know this has probably been asked a ton of times but I just wanted to clarify if I am approaching this correctly, since I ran into some problems rotating a bitmap. So basically I have one large bitmap that has four frames drawn on it and I only draw one at a time by looping through the bitmap by increments to animate walking. I can get the bitmap to rotate correctly when it is not moving but once the animation starts it starts to cut off alot of the image and sometimes becomes very fuzzy. I have tried public void draw(Canvas canvas,int pointerX, int pointerY) { Matrix m; if (setRotation){ // canvas.save(); m = new Matrix(); m.reset(); // spriteWidth and spriteHeight are for just the current frame showed m.setTranslate(spriteWidth / 2, spriteHeight / 2); //get and set rotation for ninja based off of joystick m.preRotate((float) GameControls.getRotation()); //create the rotated bitmap flipedSprite = Bitmap.createBitmap(bitmap , 0, 0,bitmap.getWidth(),bitmap.getHeight() , m, true); //set new bitmap to rotated ninja setBitmap(flipedSprite); // canvas.restore(); Log.d("Ninja View", "angle of rotation= " +(float) GameControls.getRotation()); setRotation = false; } And then the Draw Method here // create the destination rectangle for the ninjas current animation frame // pointerX and pointerY are from the joystick moving the ninja around destRect = new Rect(pointerX, pointerY, pointerX + spriteWidth, pointerY + spriteHeight); canvas.drawBitmap(bitmap, getSourceRect(), destRect, null); The animation is four frames long and gets incremented by 66 (the size of one of the frames on the bitmap) for every frame and then back to 0 at the end of the loop.

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  • How can I find a position between 4 vertices in a fragment shader?

    - by c4sh
    I'm creating a shader with SharpDX (DirectX11 in C#) that takes a segment (2 points) from the output of a Vertex Shader and then passes them to a Geometry Shader, which converts this line into a rectangle (4 points) and assigns the four corners a texture coordinate. After that I want a Fragment Shader (which recieves the interpolated position and the interpolated texture coordinates) that checks the depth at the "spine of the rectangle" (that is, in the line that passes through the middle of the rectangle. The problem is I don't know how to extract the position of the corresponding fragment at the spine of the rectangle. This happens because I have the texture coordinates interpolated, but I don't know how to use them to get the fragment I want, because the coordinate system of a) the texture and b) the position of my fragment in screen space are not the same. Thanks a lot for any help.

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  • (Libgdx) Move Vector2 along angle?

    - by gemurdock
    I have seen several answers on here about moving along angle, but I can't seem to get this to work properly for me and I am new to LibGDX... just trying to learn. These are my Vector2's that I am using for this function. public Vector2 position = new Vector2(); public Vector2 velocity = new Vector2(); public Vector2 movement = new Vector2(); public Vector2 direction = new Vector2(); Here is the function that I use to move the position vector along an angle. setLocation() just sets the new location of the image. public void move(float delta, float degrees) { position.set(image.getX() + image.getWidth() / 2, image.getY() + image.getHeight() / 2); direction.set((float) Math.cos(degrees), (float) Math.sin(degrees)).nor(); velocity.set(direction).scl(speed); movement.set(velocity).scl(delta); position.add(movement); setLocation(position.x, position.y); // Sets location of image } I get a lot of different angles with this, just not the correct angles. How should I change this function to move a Vector2 along an angle using the Vector2 class from com.badlogic.gdx.math.Vector2 within the LibGDX library? I found this answer, but not sure how to implement it. Update: I figured out part of the issue. Should convert degrees to radians. However, the angle of 0 degrees is towards the right. Is there any way to fix this? As I shouldn't have to add 90 to degrees in order to have correct heading. New code is below public void move(float delta, float degrees) { degrees += 90; // Set degrees to correct heading, shouldn't have to do this position.set(image.getX() + image.getWidth() / 2, image.getY() + image.getHeight() / 2); direction.set(MathUtils.cos(degrees * MathUtils.degreesToRadians), MathUtils.sin(degrees * MathUtils.degreesToRadians)).nor(); velocity.set(direction).scl(speed); movement.set(velocity).scl(delta); position.add(movement); setLocation(position.x, position.y); }

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  • Bad FPS for smaller size (OpenGL ES with SDL)

    - by ber4444
    If you saw my other question, well, there is still a little problem: Click here to watch on youtube Basically, the frame rate is very bad on the actual device, where for some reason the animation is scaled (it looks like the left side on the video). It is quite fast on the simulator where it is not scaled (right side). For a test, I submitted this new changeset that hard-codes the smaller size (plus increases the point size for HII regions to make the dust clouds more visible), and as you see in the video, now it is slow even in the simulator (left side shows the small size, right side shows the original size -- otherwise the code is the same). I'm clueless why it's soooo slow with a smaller galaxy, in fact it should be FASTER. As for general speed optimization (which is not strictly part of my question but is closely related to it, esp. if we need a workaround to speed things up), some initial ideas: reducing the number of items drawn may affect the appearance negatively but screen resolution could be reduced there are too many glBegin(GL_POINTS)/glEnd() blocks, we could draw more than just a single star at once

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  • How can I move a polygon edge 1 unit away from the center?

    - by Stephen
    Let's say I have a polygon class that is represented by a list of vector classes as vertices, like so: var Vector = function(x, y) { this.x = x; this.y = y; }, Polygon = function(vectors) { this.vertices = vectors; }; Now I make a polygon (in this case, a square) like so: var poly = new Polygon([ new Vector(2, 2), new Vector(5, 2), new Vector(5, 5), new Vector(2, 5) ]); So, the top edge would be [poly.vertices[0], poly.vertices[1]]. I need to stretch this polygon by moving each edge away from the center of the polygon by one unit, along that edge's normal. The following example shows the first edge, the top, moved one unit up: The final polygon should look like this new one: var finalPoly = new Polygon([ new Vector(1, 1), new Vector(6, 1), new Vector(6, 6), new Vector(1, 6) ]); It is important that I iterate, moving one edge at a time, because I will be doing some collision tests after moving each edge. Here is what I tried so far (simplified for clarity), which fails triumphantly: for(var i = 0; i < vertices.length; i++) { var a = vertices[i], b = vertices[i + 1] || vertices[0]; // in case of final vertex var ax = a.x, ay = a.y, bx = b.x, by = b.y; // get some new perpendicular vectors var a2 = new Vector(-ay, ax), b2 = new Vector(-by, bx); // make into unit vectors a2.convertToUnitVector(); b2.convertToUnitVector(); // add the new vectors to the original ones a.add(a2); b.add(b2); // the rest of the code, collision tests, etc. } This makes my polygon start slowly rotating and sliding to the left, instead of what I need. Finally, the example shows a square, but the polygons in question could be anything. They will always be convex, and always with vertices in clockwise order.

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  • Cocos2D 2.0 - masking a sprite

    - by Desperate Developer
    I have read this tutorial about how to mask sprites using Cocos2D 2.0. http://www.raywenderlich.com/4428/how-to-mask-a-sprite-with-cocos2d-2-0 But the author talks about OpenGL ES textures and vertices as they were common knowledge. My knowledge about OpenGl is zero raised to infinity. All I want is to use a rectangle to mask a sprite to it. How I would do in Photoshop using a rectangle as mask (yes, I want to clip a sprite to the rectangle bounds and no, I do not want to use the ClippingNode solution, that do not works for animation/scaling etc.). So, can you guys translate the klingon language used in this tutorial and tell how a solid rectangle can be used to mask a sprite in Cocos2D? I am desperate, as my username states. I am searching this for a week and have tried several solutions without satisfactory results. Please help me. Thanks!

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  • Sphere-Sphere intersection and Circle-Sphere intersection

    - by cagirici
    I have code for circle-circle intersection. But I need to expand it to 3-D. How do I calculate: Radius and center of the intersection circle of two spheres Points of the intersection of a sphere and a circle? Given two spheres (sc0,sr0) and (sc1,sr1), I need to calculate a circle of intersection whose center is ci and whose radius is ri. Moreover, given a sphere (sc0,sr0) and a circle (cc0, cr0), I need to calulate the two intersection points (pi0, pi1) I have checked this link and this link, but I could not understand the logic behind them and how to code them. I tried ProGAL library for sphere-sphere-sphere intersection, but the resulting coordinates are rounded. I need precise results.

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