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  • WIn API Basic Paint program

    - by Tom Burman
    Just trying to learn a bit of Win API. Im trying to make a basic drawing app, a bit like MS Paint. For the time being im trying to get one function to work which is, when you left click and drag the mouse around the screen a line is drawn behind the mouse. Heres what i have so far, but for some reason: 1) the line starts drawing straight away rather then waiting for the left click 2) the line isn't solid its very dotty. case WM_MOUSEMOVE: { if(MK_LBUTTON){ hdc = GetDC(hwnd); hPen = CreatePen(PS_SOLID,5,RGB(0, 0, 255)); SelectObject(hdc, hPen); int x = LOWORD(lParam); int y = HIWORD(lParam); MoveToEx(hdc,x,y,NULL); LineTo(hdc, LOWORD(lParam), HIWORD(lParam)); ReleaseDC(hwnd,hdc); } else break; } } Thanks for any help!

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  • Implementing top view physics using box2D

    - by humbleBee
    How can top view physics games be done in box2D? One idea I have is to set the linear velocity of an object manually or to alter the linear and angular damping as my object moves over different surfaces. For example if my object is over a wet surface it'll have less linear damping and if it is over rough surface it'll have more damping. And to see if my object has fallen over an edge I'll try to use an AABB and check if its still inside or manually see if object.x > boundary.x etc. Is there any better way?

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  • getting bone base and tip positions from a transform matrix?

    - by ddos
    I need this for a Blender3d script, but you don't really need to know Blender to answer this. I need to get bone head and tip positions from a transform matrix read from a file. The position of base is the location part of the matrix, length of the bone (distance from base to tip) is the scale, position of the tip is calculated from the scale (distance from bone base) and rotation part of the matrix. So how to calculate these? bone.base([x,y,z]) # x,y,z - floats bone.tip([x,y,z])

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  • OpenGL profiling with AMD PerfStudio 2

    - by Aurus
    I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose FPS for nothing so I keep looking for more improvements. The first thing I noticed is the "huge" time where no calls are made before SwapBuffer (the black one). Well I know that OpenGL works asynchronous so SwapBuffer has to wait until everything is done. But shouldn't PerfStudio mark this time also as black ? Correct me If I am wrong. The second thing I noticed is that some glUniform2f calls just take longer (the brown ones). I mean they should all upload 2floats to the GPU how can the time be so different from call to call. The program isn't even changed or something like that. I also tried to look at other programs like gDebugger or CodeXL but they often crashed and they show less statistics (only # of calls or redundant calls etc.) EDIT: I also realized that the draw calls also have different durations, which was obvious for me but sometimes drawing more vertices is faster than drawing less vertices.

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  • Where can I find free or buy "next-gen" 3D Assets?

    - by Valmond
    Usually I buy 3D Assets from sites like turbosquid.com or similar. My problem is that I have lately implemented glow, normal maps, specular (and specular power) maps and reflection maps and I can't find any models that use those techniques. So where can I find / buy "next gen" assets (at least models/items with a normal map)? I have checked for similar posts but those I found are about either free only or 2D or 'ordinary' 3D so I hope this is not a duplicate.

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  • What calls trigger a new batch?

    - by sebf
    I am finding my project is starting to show performance degradation and I need to optimize it. The answer to my previous question and this presentation from NVidia have helped greatly in understanding the performance characteristics of code using the GPU but there are a couple of things that aren't clear that I need to know to optimize my drawing. Specifically, what calls make the distinction between batches. I know that any state changes cause a new batch, so that includes: Render State Changes Buffer Changes Shader Changes Render Target Changes Correct? What else counts as a 'state change'? Does each Draw**Primitive() call constitute a new batch? Even if I were to issue the same call twice, with no state changes, or call it once on on part of the buffer, then again on another? If I were to update a buffer, but not change the bindings, would that be a new batch? That presentation and a DX9 page suggest using all of the texture slots available, which I take to mean loading multiple objects in 'parallel' by mapping their buffers/shaders/textures to slots 1-16. But I am not sure how this works - surely to do this you would need to change the buffer binding and that would count as a state change? (or is it a case of you do but it saves 16 calls so its OK?)

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  • Ray Tracing concers: Efficient Data Structure and Photon Mapping

    - by Grieverheart
    I'm trying to build a simple ray tracer for specific target scenes. An example of such scene can be seen below. I'm concerned as to what accelerating data structure would be most efficient in this case since all objects are touching but on the other hand, the scene is uniform. The objects in my ray tracer are stored as a collection of triangles, thus I also have access to individual triangles. Also, when trying to find the bounding box of the scene, how should infinite planes be handled? Should one instead use the viewing frustum to calculate the bounding box? A few other questions I have are about photon mapping. I've read the original paper by Jensen and many more material. In the compact data structure for the photon they introduce, they store photon power as 4 chars, which from my understanding is 3 chars for color and 1 for flux. But I don't understand how 1 char is enough to store a flux of the order of 1/n, where n is the number of photons (I'm also a bit confused about flux vs power). The other question about photon mapping is, if it would be more efficient in my case to store photons per object (or even per Object's triangle) instead of using a balanced kd-tree. Also, same question about bounding box of the scene but for photon mapping. How should one find a bounding box from the pov of the light when infinite planes are involved?

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  • How do I increase moving speed of body?

    - by Siddharth
    How to move ball speedily on the screen using box2d in libGDX? package com.badlogic.box2ddemo; import com.badlogic.gdx.ApplicationListener; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.graphics.GL10; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.g2d.Sprite; import com.badlogic.gdx.graphics.g2d.SpriteBatch; import com.badlogic.gdx.graphics.g2d.TextureRegion; import com.badlogic.gdx.math.Matrix4; import com.badlogic.gdx.math.Vector2; import com.badlogic.gdx.physics.box2d.Body; import com.badlogic.gdx.physics.box2d.BodyDef; import com.badlogic.gdx.physics.box2d.BodyDef.BodyType; import com.badlogic.gdx.physics.box2d.Box2DDebugRenderer; import com.badlogic.gdx.physics.box2d.CircleShape; import com.badlogic.gdx.physics.box2d.Fixture; import com.badlogic.gdx.physics.box2d.FixtureDef; import com.badlogic.gdx.physics.box2d.PolygonShape; import com.badlogic.gdx.physics.box2d.World; public class Box2DDemo implements ApplicationListener { private SpriteBatch batch; private TextureRegion texture; private World world; private Body groundDownBody, groundUpBody, groundLeftBody, groundRightBody, ballBody; private BodyDef groundBodyDef1, groundBodyDef2, groundBodyDef3, groundBodyDef4, ballBodyDef; private PolygonShape groundDownPoly, groundUpPoly, groundLeftPoly, groundRightPoly; private CircleShape ballPoly; private Sprite sprite; private FixtureDef fixtureDef; private Vector2 ballPosition; private Box2DDebugRenderer renderer; Vector2 vector2; @Override public void create() { texture = new TextureRegion(new Texture( Gdx.files.internal("img/red_ring.png"))); sprite = new Sprite(texture); sprite.setOrigin(sprite.getWidth() / 2, sprite.getHeight() / 2); batch = new SpriteBatch(); world = new World(new Vector2(0.0f, 0.0f), false); groundBodyDef1 = new BodyDef(); groundBodyDef1.type = BodyType.StaticBody; groundBodyDef1.position.x = 0.0f; groundBodyDef1.position.y = 0.0f; groundDownBody = world.createBody(groundBodyDef1); groundBodyDef2 = new BodyDef(); groundBodyDef2.type = BodyType.StaticBody; groundBodyDef2.position.x = 0f; groundBodyDef2.position.y = Gdx.graphics.getHeight(); groundUpBody = world.createBody(groundBodyDef2); groundBodyDef3 = new BodyDef(); groundBodyDef3.type = BodyType.StaticBody; groundBodyDef3.position.x = 0f; groundBodyDef3.position.y = 0f; groundLeftBody = world.createBody(groundBodyDef3); groundBodyDef4 = new BodyDef(); groundBodyDef4.type = BodyType.StaticBody; groundBodyDef4.position.x = Gdx.graphics.getWidth(); groundBodyDef4.position.y = 0f; groundRightBody = world.createBody(groundBodyDef4); groundDownPoly = new PolygonShape(); groundDownPoly.setAsBox(480.0f, 10f); fixtureDef = new FixtureDef(); fixtureDef.density = 0f; fixtureDef.restitution = 1f; fixtureDef.friction = 0f; fixtureDef.shape = groundDownPoly; fixtureDef.filter.groupIndex = 0; groundDownBody.createFixture(fixtureDef); groundUpPoly = new PolygonShape(); groundUpPoly.setAsBox(480.0f, 10f); fixtureDef = new FixtureDef(); fixtureDef.friction = 0f; fixtureDef.restitution = 0f; fixtureDef.density = 0f; fixtureDef.shape = groundUpPoly; fixtureDef.filter.groupIndex = 0; groundUpBody.createFixture(fixtureDef); groundLeftPoly = new PolygonShape(); groundLeftPoly.setAsBox(10f, 320f); fixtureDef = new FixtureDef(); fixtureDef.friction = 0f; fixtureDef.restitution = 0f; fixtureDef.density = 0f; fixtureDef.shape = groundLeftPoly; fixtureDef.filter.groupIndex = 0; groundLeftBody.createFixture(fixtureDef); groundRightPoly = new PolygonShape(); groundRightPoly.setAsBox(10f, 320f); fixtureDef = new FixtureDef(); fixtureDef.friction = 0f; fixtureDef.restitution = 0f; fixtureDef.density = 0f; fixtureDef.shape = groundRightPoly; fixtureDef.filter.groupIndex = 0; groundRightBody.createFixture(fixtureDef); ballPoly = new CircleShape(); ballPoly.setRadius(16f); fixtureDef = new FixtureDef(); fixtureDef.shape = ballPoly; fixtureDef.density = 1f; fixtureDef.friction = 1f; fixtureDef.restitution = 1f; ballBodyDef = new BodyDef(); ballBodyDef.type = BodyType.DynamicBody; ballBodyDef.position.x = (int) 200; ballBodyDef.position.y = (int) 200; ballBody = world.createBody(ballBodyDef); ballBody.setLinearVelocity(200f, 200f); // ballBody.applyLinearImpulse(new Vector2(250f, 250f), // ballBody.getLocalCenter()); ballBody.createFixture(fixtureDef); renderer = new Box2DDebugRenderer(true, false, false); } @Override public void dispose() { ballPoly.dispose(); groundLeftPoly.dispose(); groundUpPoly.dispose(); groundDownPoly.dispose(); groundRightPoly.dispose(); world.destroyBody(ballBody); world.dispose(); } @Override public void pause() { } @Override public void render() { world.step(1f/30f, 3, 3); Gdx.gl.glClearColor(1f, 1f, 1f, 1f); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); batch.begin(); vector2 = ballBody.getLinearVelocity(); System.out.println("X=" + vector2.x + " Y=" + vector2.y); ballPosition = ballBody.getPosition(); renderer.render(world,batch.getProjectionMatrix()); // int preX = (int) (vector2.x / Math.abs(vector2.x)); // int preY = (int) (vector2.y / Math.abs(vector2.y)); // // if (Math.abs(vector2.x) == 0.0f) // ballBody1.setLinearVelocity(1.4142137f, vector2.y); // else if (Math.abs(vector2.x) < 1.4142137f) // ballBody1.setLinearVelocity(preX * 5, vector2.y); // // if (Math.abs(vector2.y) == 0.0f) // ballBody1.setLinearVelocity(vector2.x, 1.4142137f); // else if (Math.abs(vector2.y) < 1.4142137f) // ballBody1.setLinearVelocity(vector2.x, preY * 5); batch.draw(sprite, (ballPosition.x - (texture.getRegionWidth() / 2)), (ballPosition.y - (texture.getRegionHeight() / 2))); batch.end(); } @Override public void resize(int arg0, int arg1) { } @Override public void resume() { } } I implement above code but I can not achieve higher moving speed of the ball

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  • How can I downsample a texture using FBOs?

    - by snape
    I am rendering a scene to FBO as my render target whose size is 8 times the size of the orignal screen in OpenGL. Now i wan to downsample the texture generated by FBO to the size of the screen so as to achieve spatial anti aliasing. How do i achieve the down sampling ? Please provide implementation details. Note : If there is a better way of doing anti aliasing in FBOs please mention that too. I am trying to remove the aliasing in the image attached below.

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  • Finding direction of travel in a world with wrapped edges

    - by crazy
    I need to find the shortest distance direction from one point in my 2D world to another point where the edges are wrapped (like asteroids etc). I know how to find the shortest distance but am struggling to find which direction it's in. The shortest distance is given by: int rows = MapY; int cols = MapX; int d1 = abs(S.Y - T.Y); int d2 = abs(S.X - T.X); int dr = min(d1, rows-d1); int dc = min(d2, cols-d2); double dist = sqrt((double)(dr*dr + dc*dc)); Example of the world : : T : :--------------:--------- : : : S : : : : : : T : : : :--------------: In the diagram the edges are shown with : and -. I've shown a wrapped repeat of the world at the top right too. I want to find the direction in degrees from S to T. So the shortest distance is to the top right repeat of T. but how do I calculate the direction in degreed from S to the repeated T in the top right? I know the positions of both S and T but I suppose I need to find the position of the repeated T however there more than 1. The worlds coordinates system starts at 0,0 at the top left and 0 degrees for the direction could start at West. It seems like this shouldn’t be too hard but I haven’t been able to work out a solution. I hope somone can help? Any websites would be appreciated.

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  • 2d Ice movement

    - by Jeremy Clarkson
    I am building an top-down 2d RPG like zelda. I have been trying to implement ice sliding. I have a tile with the slide property. I thought it would be easy to get working. I figured that I would read the slide property, and move the character forward until the slide property no longer exists. So I tried a loop but all it did was stop at the first tile in an infinite loop. I then took the loop out and tried taking direct control of the character to move him along the slide path but I couldn't get it to move. Is there an easy way to do an ice sliding tile based movement in libgdx. I looked for a tutorial but none exist.

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  • Can't get sprite to rotate correctly?

    - by rphello101
    I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was to keep track of the angle the sprite is at since I have to multiply the cosine/sine of the angle by the move speed in order to get the sprite to go "forwards" even if it is, say, facing 45 degrees in quadrant 3. However, before I even worry about that, I'm having trouble even getting my sprite to rotate in the first place. Preliminary console tests showed that this code worked, but when applied to the sprite, it just kind twitches. Anyone know what's wrong? int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x; int pY = sprite.y; int tempY, tempX; double mAng, pAng = sprite.angle; double angRotate=0; if(mX!=pX){ tempY=pY-mY; tempX=mX-pX; mAng = Math.toDegrees(Math.atan2(Math.abs((tempY)),Math.abs((tempX)))); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=270; else mAng=90; } //Calculations if(mX<pX&&mY<pY){ //If in Q2 mAng = 180-mAng; } if(mX<pX&&mY>pY){ //If in Q3 mAng = 180+mAng; } if(mX>pX&&mY>pY){ //If in Q4 mAng = 360-mAng; } angRotate = mAng-pAng; sprite.angle = mAng; sprite.image.setRotation((float)angRotate);

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  • Box2d world width and height ratio with screen width and height

    - by Sujith
    I have view, for example GameView which extends SurfaceView . I have integrated Box2D physics in GameView. I have two widths , GameView width, height and Box2D physics world width ,height. I need to get the position of box2d world with the GameView co-ordinates. For example, Total width of screen = 240 Total height of screen = 320 Screen points needed to be mapped onto box2d co-ordinates (x,y) = 127, 139 For this i need to get the max width and height of the Box2d physics world. Is there is any way to get the max width and height of Box2d world. or Can i limit the width and height of box2d world within the screen resolution.

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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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  • Texture errors in CubeMap

    - by shade4159
    I am trying to apply this texture as a cubemap. This is my result: Clearly I am doing something with my texture coordinates, but I cannot for the life of me figure out what. I don't even see a pattern to the texture fragments. They just seem like a jumble of different faces. Can anyone shed some light on this? Vertex shader: #version 400 in vec4 vPosition; in vec3 inTexCoord; smooth out vec3 texCoord; uniform mat4 projMatrix; void main() { texCoord = inTexCoord; gl_Position = projMatrix * vPosition; } My fragment shader: #version 400 smooth in vec3 texCoord; out vec4 fColor; uniform samplerCube textures void main() { fColor = texture(textures,texCoord); } Vertices of cube: point4 worldVerts[8] = { vec4( 15, 15, 15, 1 ), vec4( -15, 15, 15, 1 ), vec4( -15, 15, -15, 1 ), vec4( 15, 15, -15, 1 ), vec4( -15, -15, 15, 1 ), vec4( 15, -15, 15, 1 ), vec4( 15, -15, -15, 1 ), vec4( -15, -15, -15, 1 ) }; Cube rendering: void worldCube(point4* verts, int& Index, point4* points, vec3* texVerts) { quadInv( verts[0], verts[1], verts[2], verts[3], 1, Index, points, texVerts); quadInv( verts[6], verts[3], verts[2], verts[7], 2, Index, points, texVerts); quadInv( verts[4], verts[5], verts[6], verts[7], 3, Index, points, texVerts); quadInv( verts[4], verts[1], verts[0], verts[5], 4, Index, points, texVerts); quadInv( verts[5], verts[0], verts[3], verts[6], 5, Index, points, texVerts); quadInv( verts[4], verts[7], verts[2], verts[1], 6, Index, points, texVerts); } Backface function (since this is the inside of the cube): void quadInv( const point4& a, const point4& b, const point4& c, const point4& d , int& Index, point4* points, vec3* texVerts) { quad( a, d, c, b, Index, points, texVerts, a.to_3(), b.to_3(), c.to_3(), d.to_3()); } And the quad drawing function: void quad( const point4& a, const point4& b, const point4& c, const point4& d, int& Index, point4* points, vec3* texVerts, const vec3& tex_a, const vec3& tex_b, const vec3& tex_c, const vec3& tex_d) { texVerts[Index] = tex_a.normalized(); points[Index] = a; Index++; texVerts[Index] = tex_b.normalized(); points[Index] = b; Index++; texVerts[Index] = tex_c.normalized(); points[Index] = c; Index++; texVerts[Index] = tex_a.normalized(); points[Index] = a; Index++; texVerts[Index] = tex_c.normalized(); points[Index] = c; Index++; texVerts[Index] = tex_d.normalized(); points[Index] = d; Index++; } Edit: I forgot to mention, in the image, the camera is pointed directly at the back face of the cube. You can kind of see the diagonals leading out of the corners, if you squint.

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  • OpenGLES GLSL Shader attributes always bound to 0

    - by codemonkey
    So I have a very simple vertex shader as follows #version 120 attribute vec3 position; attribute vec3 inColor; uniform mat4 mvp; varying vec3 fragColor; void main(void){ fragColor = inColor; gl_Position = mvp * vec4(position, 1.0); } Which I load, as well as the fragment shader: #version 120 varying vec3 fragColor; void main(void) { gl_FragColor = vec4(fragColor,1.0); } Which I then load, compile, and link to my shader program. I check for link status using glGetProgramiv(shaderProgram, GL_LINK_STATUS, &shaderSuccess); which returns GL_TRUE so I think its ok. However, when I query the active attributes and uniforms using #ifdef DEBUG int totalAttributes = -1; glGetProgramiv(shaderProgram, GL_ACTIVE_ATTRIBUTES, &totalAttributes); for(int i=0; i<totalAttributes; ++i) { int name_len=-1, num=-1; GLenum type = GL_ZERO; char name[100]; glGetActiveAttrib(shaderProgram, GLuint(i), sizeof(name)-1, &name_len, &num, &type, name ); name[name_len] = 0; GLuint location = glGetAttribLocation(shaderProgram, name); fprintf(stderr, "Attribute %s is bound at %d\n", name, location); } int totalUniforms = -1; glGetProgramiv(shaderProgram, GL_ACTIVE_UNIFORMS, &totalUniforms); for(int i=0; i<totalUniforms; ++i) { int name_len=-1, num=-1; GLenum type = GL_ZERO; char name[100]; glGetActiveUniform(shaderProgram, GLuint(i), sizeof(name)-1, &name_len, &num, &type, name ); name[name_len] = 0; GLuint location = glGetUniformLocation(shaderProgram, name); fprintf(stderr, "Uniform %s is bound at %d\n", name, location); } #endif I get: Attribute inColor is bound at 0 Attribute position is bound at 1 Uniform mvp is bound at 0 Which leads to failure when trying to use the shader to render the objects. I have tried switching the order of declaration of position & inColor, but still, only position is bound with the other two giving 0 Can someone please explain why this is happening? Thanks

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  • fast java2d translucency

    - by mdriesen
    I'm trying to draw a bunch of translucent circles on a Swing JComponent. This isn't exactly fast, and I was wondering if there is a way to speed it up. My custom JComponent has the following paintComponent method: public void paintComponent(Graphics g) { Rectangle view = g.getClipBounds(); VolatileImage image = createVolatileImage(view.width, view.height); Graphics2D buffer = image.createGraphics(); // translate to camera location buffer.translate(-cx, -cy); // renderables contains all currently visible objects for(Renderable r : renderables) { r.paint(buffer); } g.drawImage(image.getSnapshot(), view.x, view.y, this); } The paint method of my circles is as follows: public void paint(Graphics2D graphics) { graphics.setPaint(paint); graphics.fillOval(x, y, radius, radius); } The paint is just an rgba color with a < 255: Color(int r, int g, int b, int a) It works fast enough for opaque objects, but is there a simple way to speed this up for translucent ones?

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  • Trying to figure out SDL pixel manipulation?

    - by NoobScratcher
    Hello so I've found code that plots a pixel in an SDL Screen Surface : void putpixels(int x, int y, int color) { unsigned int *ptr = (unsigned int*)Screen->pixels; int lineoffset = y * (Screen->pitch / 4 ); ptr[lineoffset + x ] = color; } But I have no idea what its actually doing here this is my thoughts. You make an unsigned integer to hold the unsigned int version of pixels then you make another integer to hold the line offset and it equals to multiply by pitch which is then divided by 4 ... Now why am I dividing it by 4 and what is the pitch and why do I multiply it?? Why must I change the lineoffset and add it to the x value then equal it to colors? I'm soo confused.. ;/ I found this function here - http://sol.gfxile.net/gp/ch02.html

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  • Getting the number of fragments which passed the depth test

    - by Etan
    In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension is not available. What is the most performant approach to implement a similar behaviour in the fragment shader? Some of my ideas: Render the object completely in white, then count all the colors together using a two-pass shader where first a vertical line is rendered and for each fragment the shader computes the sum over the whole row. Then, a single vertex is rendered whose fragment sums all the partial sums of the first pass. Doesn't seem to be very efficient. Render the object completely in white over a black background. Downsample recursively, abusing the hardware linear interpolation between textures until being at a reasonably small resolution. This leads to fragments which have a greyscale level depending on the number of white pixels where in their corresponding region. Is this even accurate enough? Use mipmaps and simply read the pixel on the 1x1 level. Again the question of accuracy and if it is even possible using non-power-of-two textures. The problem wit these approaches is, that the pipeline gets stalled which results in major performance issues. Therefore, I'm looking for a more performant way to accomplish my goal. Using the EXT_OCCLUSION_QUERY_BOOLEAN extension Apple introduced EXT_OCCLUSION_QUERY_BOOLEAN in iOS 5.0 for iPad 2. "4.1.6 Occlusion Queries Occlusion queries use query objects to track the number of fragments or samples that pass the depth test. An occlusion query can be started and finished by calling BeginQueryEXT and EndQueryEXT, respectively, with a target of ANY_SAMPLES_PASSED_EXT or ANY_SAMPLES_PASSED_CONSERVATIVE_EXT. When an occlusion query is started with the target ANY_SAMPLES_PASSED_EXT, the samples-boolean state maintained by the GL is set to FALSE. While that occlusion query is active, the samples-boolean state is set to TRUE if any fragment or sample passes the depth test. When the occlusion query finishes, the samples-boolean state of FALSE or TRUE is written to the corresponding query object as the query result value, and the query result for that object is marked as available. If the target of the query is ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, an implementation may choose to use a less precise version of the test which can additionally set the samples-boolean state to TRUE in some other implementation dependent cases." The first sentence hints on a behavior which is exactly what I'm looking for: getting the number of pixels which passed the depth test in an asynchronous manner without much performance loss. However, the rest of the document describes only how to get boolean results. Is it possible to exploit this extension to get the pixel count? Does the hardware support it so that there may be hidden API to get access to the pixel count? Other extensions which could be exploitable would be debugging features like the number of times the fragment shader was invoked (PSInvocations in DirectX - not sure if something simila is available in OpenGL ES). However, this would also result in a pipeline stall.

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  • OpenGL ES Loading

    - by kuroutadori
    I want to know what is the norm of loading rendering code. Take a button. When the application is loaded, a texture is loaded which has the image of the button on it. When the button is tapped, it then adds a loader into a queue, which is loaded on render thread. It then loads up an array buffer with vertexes and tex coords when render is called. It then adds to a render tree. Then it renders. the render function looks like this void render() { update(); mBaseRenderer->render(); } update() is when the queue is checked to see if anything needs loading. mBaseRenderer->render() is the render tree. What I am asking then is, should I even have the update() there at all and instead have everything preloaded before it renders? If I can have it loaded when need, for instance when there is tap, then how can it be done (My current code causes an dequeueing buffer error (Unknown error: -75) which I assume is to do with OpenGL ES and the context)?

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  • XNA texture stretching at extreme coordinates

    - by Shaun Hamman
    I was toying around with infinitely scrolling 2D textures using the XNA framework and came across a rather strange observation. Using the basic draw code: spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.PointWrap, null, null); spriteBatch.Draw(texture, Vector2.Zero, sourceRect, Color.White, 0.0f, Vector2.Zero, 2.0f, SpriteEffects.None, 1.0f); spriteBatch.End(); with a small 32x32 texture and a sourceRect defined as: sourceRect = new Rectangle(0, 0, Window.ClientBounds.Width, Window.ClientBounds.Height); I was able to scroll the texture across the window infinitely by changing the X and Y coordinates of the sourceRect. Playing with different coordinate locations, I noticed that if I made either of the coordinates too large, the texture no longer drew and was instead replaced by either a flat color or alternating bands of color. Tracing the coordinates back down, I found the following at around (0, -16,777,000): As you can see, the texture in the top half of the image is stretched vertically. My question is why is this occurring? Certainly I can do things like bind the x/y position to some low multiple of 32 to give the same effect without this occurring, so fixing it isn't an issue, but I'm curious about why this happens. My initial thought was perhaps it was overflowing the coordinate value or some such thing, but looking at a data type size chart, the next closest below is an unsigned short with a range of about 32,000, and above is an unsigned int with a range of around 2,000,000,000 so that isn't likely the cause.

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  • Is a Single Texture Cube Map Possible?

    - by smoth190
    I'm currently developing a test project to explore OpenGL 3 texturing abilities. I have a simple cube, made of 8 vertices and 36 indices. I want each of the cubes faces to have a different texture, so I devised this texture: I made it obvious which sections I want visible (I hope...). In Direct3D, I once made a skybox, and I used a cubemap. However, I had to split it into 6 different textures. This is annoying and hard to manage, it would be nice to have just one texture. Is this even possible? I read somewhere that I could do this by duplicating vertices, is that a good idea? Someone else said I could do it in the shader, but that also baffles me...

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  • Safe zone implementation in Asteroids

    - by Moaz
    I would like to implement a safe zone for asteroids so that when the ship gets destroyed, it shouldn't be there unless it is safe from other asteroids. I tried to check the distance between each asteroid and the ship, and if it is above threshold, it sets a flag to the ship that's a safe zone, but sometimes it work and sometimes it doesn't. What am I doing wrong? Here's my code: for (list<Asteroid>::iterator itr_astroid = asteroids.begin(); itr_astroid!=asteroids.end(); ) { if(currentShip.m_state == Ship::Ship_Dead) { float distance = itr_astroid->getCenter().distance(Vec2f(getWindowWidth()/2,getWindowHeight()/2)); if( distance>200) { currentShip.m_saveField = true; break; } else { currentShip.m_saveField = false; itr_astroid++; } } else { itr_astroid++; } } At ship's death: if(m_state == Ship_Dead && m_saveField==true) { --m_lifeSpan; } if(m_lifeSpan<=0 && m_saveField == true) { m_state = Ship_Alive; m_Vel = Vec2f(0,0); m_Pos.x = app::getWindowWidth()/2; m_Pos.y = app::getWindowHeight()/2; m_lifeSpan = 100; }

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  • 3D zooming technique to maintain the relative position of an object on screen

    - by stark
    Is it possible to zoom to a certain point on screen by modifying the field of view and rotating the view of the camera as to keep that point/object in the same place on screen while zooming ? Changing the camera position is not allowed. I projected the 3D pos of the object on screen and remembered it. Then on each frame I calculate the direction to it in camera space and then I construct a rotation matrix to align this direction to Z axis (in cam space). After this, I calculate the direction from the camera to the object in world space and transform this vector with the matrix I obtained earlier and then use this final vector as the camera's new direction. And it's actually "kinda working", the problem is that it is more/less off than the camera's rotation before starting to zoom depending on the area you are trying to zoom in (larger error on edges/corners). It looks acceptable, but I'm not settling for only this. Any suggestions/resources for doing this technique perfectly? If some of you want to explain the math in detail, be my guest, I can understand these things well.

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  • My server is behind a router. How can I see my website correctly? [closed]

    - by Tokyo Dan
    I'm running a web server (Ubuntu) on my local home network. I'm behind a router. On the WAN I have a direct IP. When not on my home network and accessing my website via the WAN direct IP my website displays correctly and everything works. On my home LAN behind the router, accessing my website via the WAN direct gets me to my router's admin login page. This is normal. But... Accessing my website (via it's home LAN IP address) from another computer on my home LAN gets me to the website but the layout display is broken and clicking on any link takes me to the WAN direct IP (my router's Admin login page). How can i get my website to display properly and the links to work when accessing it from my home LAN?

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