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• How to modulate every texture unit in OpenGL ES 1.1?

  - by Jesse Beder

  I have two textures and a "blend factor", and I'd like to mix them, modulated by the current color; in effect, I want to use the following shader: gl_FragColor = gl_Color * mix(tex0, tex1, blendFactor); I'm using OpenGL ES 1.1, targeting all versions of the iPhone, so I can't use shaders, and I have two texture units. My best attempt is: // texture 0 glActiveTexture(GL_TEXTURE0); image1.Bind(); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); // texture 1 glActiveTexture(GL_TEXTURE1); image2.Bind(); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE); glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE); glTexEnvi(GL_TEXTURE_ENV, GL_SRC0_RGB, GL_PREVIOUS); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_SRC1_RGB, GL_TEXTURE); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR); glTexEnvi(GL_TEXTURE_ENV, GL_SRC2_RGB, GL_CONSTANT); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_ALPHA); glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_INTERPOLATE); glTexEnvi(GL_TEXTURE_ENV, GL_SRC0_ALPHA, GL_PREVIOUS); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA); glTexEnvi(GL_TEXTURE_ENV, GL_SRC1_ALPHA, GL_TEXTURE); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA, GL_SRC_ALPHA); glTexEnvi(GL_TEXTURE_ENV, GL_SRC2_ALPHA, GL_CONSTANT); glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_ALPHA, GL_SRC_ALPHA); const float factor[] = { 0, 0, 0, blendFactor }; glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, factor); This has the effect of the shader: gl_FragColor = mix(gl_Color * tex0, tex1, blendFactor); but I don't see how to module texture 1 by the color. Is there any way to have the color provided by a texture unit automatically modulated by the incoming primary color? Or any other way to do what I want that I'm missing? Multiple passes are definitely allowed, but they have to have the proper blend effect; I have glBlend(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); enabled, so it can be tricky to get right with multiple passes.

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• OpenGL ES - texture map all faces of an 8 vertex cube?

  - by Feet

  Working through some OpenGL-ES tutorials, using the Android emulator. I've gotten up to texture mapping and am having some trouble mapping to a cube. Is it possible to map a texture to all faces of a cube that has 8 vertices and 12 triangles for the 6 faces as described below? // Use half as we are going for a 0,0,0 centre. width /= 2; height /= 2; depth /= 2; float vertices[] = { -width, -height, depth, // 0 width, -height, depth, // 1 width, height, depth, // 2 -width, height, depth, // 3 -width, -height, -depth, // 4 width, -height, -depth, // 5 width, height, -depth, // 6 -width, height, -depth, // 7 }; short indices[] = { // Front 0,1,2, 0,2,3, // Back 5,4,7, 5,7,6, // Left 4,0,3, 4,3,7, // Right 1,5,6, 1,6,2, // Top 3,2,6, 3,6,7, // Bottom 4,5,1, 4,1,0, }; float texCoords[] = { 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; I have gotten the front and back faces working correctly, however, none of the other faces are showing the texture.

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• OpenGL ES - how to keep some object at a fixed size?

  - by OMH

  I'm working on a little game in OpenGL ES. In the background, there is a world/map. The map is just a large texture. Zoom/pinch/pan is used to move around. And I'm using glOrthof (left, right, bottom, top, zNear, zFar) to implement the zoom/pinch. When I zoom in, the sprites on top of the map is also zoomed in. But I would like to have some sprites stay at a fixed size. I could probably calculate a scale factor, depending on the parameters to glOrthof, but there must be a more natural and straightforward way of doing that, instead of scaling the sprites down when I zoom in. If I add some text or some GUI elements on top of the map, they should definately have a fixed size. Is there a solution to do this, or do I have to leave fixed values in glOrthof and implement zoom/pinch in another way? EDIT: To be more clear: I want sprites that zoom in/out along with the map, but stay at the same size. I have some elements that are like the pins on the iPhone's map application. When you zoom, the pins stay the same size, but move around on the screen to stay on the same spot on the map. That is mainly what I want a solution for. Solutions for this already came below, thanks!

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• OpenGL fast texture drawing with vertex buffer objects. Is this the way to do it?

  - by Matthew Mitchell

  Hello. I am making a 2D game with OpenGL. I would like to speed up my texture drawing by using VBOs. Currently I am using the immediate mode. I am generating my own coordinates when I rotate and scale a texture. I also have the functionality of rounding the corners of a texture, using the polygon primitive to draw those. I was thinking, would it be fastest to make a VBO with vertices for the sides of the texture with no offset included so I can then use glViewport, glScale (Or glTranslate? What is the difference and most suitable here?) and glRotate to move the drawing position for my texture. Then I can use the same VBO with no changes to draw the texture each time. I could only change the VBO when I need to add coordinates for the rounded corners. Is that the best way to do this? What things should I look out for while doing it? Is it really fastest to use GL_TRIANGLES instead of GL_QUADS in modern graphics cards? Thank you for any answer.

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• LWJGL Voxel game, glDrawArrays

  - by user22015

  I've been learning about 3D for a couple days now. I managed to create a chunk (8x8x8). Add optimization so it only renders the active and visible blocks. Then I added so it only draws the faces which don't have a neighbor. Next what I found from online research was that it is better to use glDrawArrays to increase performance. So I restarted my little project. Render an entire chunck, add optimization so it only renders active and visible blocks. But now I want to add so it only draws the visible faces while using glDrawArrays. This is giving me some trouble with calling glDrawArrays because I'm passing a wrong count parameter. > # A fatal error has been detected by the Java Runtime Environment: > # > # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000000006e31a03, pid=1032, tid=3184 > # Stack: [0x00000000023a0000,0x00000000024a0000], sp=0x000000000249ef70, free space=1019k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) C [ig4icd64.dll+0xa1a03] Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) j org.lwjgl.opengl.GL11.nglDrawArrays(IIIJ)V+0 j org.lwjgl.opengl.GL11.glDrawArrays(III)V+20 j com.vox.block.Chunk.render()V+410 j com.vox.ChunkManager.render()V+30 j com.vox.Game.render()V+11 j com.vox.GameHandler.render()V+12 j com.vox.GameHandler.gameLoop()V+15 j com.vox.Main.main([Ljava/lang/StringV+13 v ~StubRoutines::call_stub public class Chunk { public final static int[] DIM = { 8, 8, 8}; public final static int CHUNK_SIZE = (DIM[0] * DIM[1] * DIM[2]); Block[][][] blocks; private int index; private int vBOVertexHandle; private int vBOColorHandle; public Chunk(int index) { this.index = index; vBOColorHandle = GL15.glGenBuffers(); vBOVertexHandle = GL15.glGenBuffers(); blocks = new Block[DIM[0]][DIM[1]][DIM[2]]; for(int x = 0; x < DIM[0]; x++){ for(int y = 0; y < DIM[1]; y++){ for(int z = 0; z < DIM[2]; z++){ blocks[x][y][z] = new Block(); } } } } public void render(){ Block curr; FloatBuffer vertexPositionData2 = BufferUtils.createFloatBuffer(CHUNK_SIZE * 6 * 12); FloatBuffer vertexColorData2 = BufferUtils.createFloatBuffer(CHUNK_SIZE * 6 * 12); int counter = 0; for(int x = 0; x < DIM[0]; x++){ for(int y = 0; y < DIM[1]; y++){ for(int z = 0; z < DIM[2]; z++){ curr = blocks[x][y][z]; boolean[] neightbours = validateNeightbours(x, y, z); if(curr.isActive() && !neightbours[6]) { float[] arr = curr.createCube((index*DIM[0]*Block.BLOCK_SIZE*2) + x*2, y*2, z*2, neightbours); counter += arr.length; vertexPositionData2.put(arr); vertexColorData2.put(createCubeVertexCol(curr.getCubeColor())); } } } } vertexPositionData2.flip(); vertexPositionData2.flip(); FloatBuffer vertexPositionData = BufferUtils.createFloatBuffer(vertexColorData2.position()); FloatBuffer vertexColorData = BufferUtils.createFloatBuffer(vertexColorData2.position()); for(int i = 0; i < vertexPositionData2.position(); i++) vertexPositionData.put(vertexPositionData2.get(i)); for(int i = 0; i < vertexColorData2.position(); i++) vertexColorData.put(vertexColorData2.get(i)); vertexColorData.flip(); vertexPositionData.flip(); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOVertexHandle); GL15.glBufferData(GL15.GL_ARRAY_BUFFER, vertexPositionData, GL15.GL_STATIC_DRAW); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOColorHandle); GL15.glBufferData(GL15.GL_ARRAY_BUFFER, vertexColorData, GL15.GL_STATIC_DRAW); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0); GL11.glPushMatrix(); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOVertexHandle); GL11.glVertexPointer(3, GL11.GL_FLOAT, 0, 0L); GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vBOColorHandle); GL11.glColorPointer(3, GL11.GL_FLOAT, 0, 0L); System.out.println("Counter " + counter); GL11.glDrawArrays(GL11.GL_LINE_LOOP, 0, counter); GL11.glPopMatrix(); //blocks[r.nextInt(DIM[0])][2][r.nextInt(DIM[2])].setActive(false); } //Random r = new Random(); private float[] createCubeVertexCol(float[] CubeColorArray) { float[] cubeColors = new float[CubeColorArray.length * 4 * 6]; for (int i = 0; i < cubeColors.length; i++) { cubeColors[i] = CubeColorArray[i % CubeColorArray.length]; } return cubeColors; } private boolean[] validateNeightbours(int x, int y, int z) { boolean[] bools = new boolean[7]; bools[6] = true; bools[6] = bools[6] && (bools[0] = y > 0 && y < DIM[1]-1 && blocks[x][y+1][z].isActive());//top bools[6] = bools[6] && (bools[1] = y > 0 && y < DIM[1]-1 && blocks[x][y-1][z].isActive());//bottom bools[6] = bools[6] && (bools[2] = z > 0 && z < DIM[2]-1 && blocks[x][y][z+1].isActive());//front bools[6] = bools[6] && (bools[3] = z > 0 && z < DIM[2]-1 && blocks[x][y][z-1].isActive());//back bools[6] = bools[6] && (bools[4] = x > 0 && x < DIM[0]-1 && blocks[x+1][y][z].isActive());//left bools[6] = bools[6] && (bools[5] = x > 0 && x < DIM[0]-1 && blocks[x-1][y][z].isActive());//right return bools; } } public class Block { public static final float BLOCK_SIZE = 1f; public enum BlockType { Default(0), Grass(1), Dirt(2), Water(3), Stone(4), Wood(5), Sand(6), LAVA(7); int BlockID; BlockType(int i) { BlockID=i; } } private boolean active; private BlockType type; public Block() { this(BlockType.Default); } public Block(BlockType type){ active = true; this.type = type; } public float[] getCubeColor() { switch (type.BlockID) { case 1: return new float[] { 1, 1, 0 }; case 2: return new float[] { 1, 0.5f, 0 }; case 3: return new float[] { 0, 0f, 1f }; default: return new float[] {0.5f, 0.5f, 1f}; } } public float[] createCube(float x, float y, float z, boolean[] neightbours){ int counter = 0; for(boolean b : neightbours) if(!b) counter++; float[] array = new float[counter*12]; int offset = 0; if(!neightbours[0]){//top array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[1]){//bottom array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } if(!neightbours[2]){//front array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[3]){//back array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } if(!neightbours[4]){//left array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; } if(!neightbours[5]){//right array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = x*BLOCK_SIZE + BLOCK_SIZE; array[offset++] = y*BLOCK_SIZE - BLOCK_SIZE; array[offset++] = z*BLOCK_SIZE - BLOCK_SIZE; } return Arrays.copyOf(array, offset); } public boolean isActive() { return active; } public void setActive(boolean active) { this.active = active; } public BlockType getType() { return type; } public void setType(BlockType type) { this.type = type; } } I highlighted the code I'm concerned about in this following screenshot: - http://imageshack.us/a/img820/7606/18626782.png - (Not allowed to upload images yet) I know the code is a mess but I'm just testing stuff so I wasn't really thinking about it.

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• Why is this OpenGL ES code slow on iPhone?

  - by f3r3nc

  I've slightly modified the iPhone SDK's GLSprite example while learning OpenGL ES and it turns out to be quite slow. Even in the simulator (on the hw worst) so I must be doing something wrong since it's only 400 textured triangles. const GLfloat spriteVertices[] = { 0.0f, 0.0f, 100.0f, 0.0f, 0.0f, 100.0f, 100.0f, 100.0f }; const GLshort spriteTexcoords[] = { 0,0, 1,0, 0,1, 1,1 }; - (void)setupView { glViewport(0, 0, backingWidth, backingHeight); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrthof(0.0f, backingWidth, backingHeight,0.0f, -10.0f, 10.0f); glMatrixMode(GL_MODELVIEW); glClearColor(0.3f, 0.0f, 0.0f, 1.0f); glVertexPointer(2, GL_FLOAT, 0, spriteVertices); glEnableClientState(GL_VERTEX_ARRAY); glTexCoordPointer(2, GL_SHORT, 0, spriteTexcoords); glEnableClientState(GL_TEXTURE_COORD_ARRAY); // sprite data is preloaded. 512x512 rgba8888 glGenTextures(1, &spriteTexture); glBindTexture(GL_TEXTURE_2D, spriteTexture); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData); free(spriteData); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glEnable(GL_TEXTURE_2D); glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); glEnable(GL_BLEND); } - (void)drawView { .. glClear(GL_COLOR_BUFFER_BIT); glLoadIdentity(); glTranslatef(tx-100, ty-100,10); for (int i=0; i<200; i++) { glTranslatef(1, 1, 0); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } .. } drawView is called every time the screen is touched or the finger on the screen is moved and tx,ty are set to the x,y coordinates where that touch happened. I've also tried using GLBuffer, when translation was pre-generated and there was only one DrawArray but gave the same performance (~4 FPS). ===EDIT=== Meanwhile I've modified this so that much smaller quads are used (sized: 34x20) and much less overlapping is done. There are ~400 quads-800 triangles spread on the whole screen. Texture size is 512x512 atlas and RGBA_8888 while the texture coordinates are in float. The code is very ugly in terms of API efficiency: there are two MatrixMode change along with two loads and two translation then a drawarrays for a triangle strip (quad). Now this produces ~45 FPS.

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• Beginning with first project on game development [closed]

  - by Tsvetan

  Today is the day I am going to start my first real game project. It will be a Universe simulator. Basically, you can build anything from tiny meteor to quazars and universes. It is going to be my project for an olympiad in IT in my country and I really want to make it perfect(at least a bronze medal). So, I would like to ask some questions about organization and development methodologies. Firstly, my plan is to make a time schedule. In it I would write my plans for the next month or two(because that is the time I have). With this exact plan I hope to make my organisation at its best. Of course, if I am doing sth faster than the schedule I would involve more features for the game and/or continue with the tempo I have. Also, for the organisation I would make a basic pseudocode(maybe) and just rewrite it so it is compilable. Like a basic skeleton of everything. The last is an idea I tought of in the moment, but if it is good I will use it. Secondly, for the development methodologies, obviously, I think of making object-oriented code and make everything perfect(a lot of testing, good code, documentation etc.). Also, I am going to make my own menu system(I read that OpenGL hasn't got very good one). Maybe I would implement it with an xml file, holding the info about position of buttons, text boxes, images and everything. Maybe I would do a specific CSS for it and so on. I think that is very good way of doing the menu system, because it makes the presentation layer separate of the logic. But, if there is a better way, I would do it the better way. For the logic, well, I don't have much to say. OO code, testing, debuging, good and fast algorithms and so on. Also, a good documentation must be written and this is the area I need to make some research in. I think that is for now. I hope I have been enough descriptive. If more questions come on my mind, I will ask them. Edit: I think of blogging every part of the project, or at least writing down everything in a file or something like that. My question is: Is my plan of how to do everything around the project good? And if not, what is necessary to be improved and what other things I can involve for making the project good.

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• How do I draw a scene with 2 nested frames

  - by Guido Granobles

  I have been trying for long time to figure out this: I have loaded a model from a directx file (I am using opengl and Java) the model have a hierarchical system of nested reference frames (there are not bones). There are just 2 frames, one of them is called x3ds_Torso and it has a child frame called x3ds_Arm_01. Each one of them has a mesh. The thing is that I can't draw the arm connected to the body. Sometimes the body is in the center of the screen and the arm is at the top. Sometimes they are both in the center. I know that I have to multiply the matrix transformation of every frame by its parent frame starting from the top to the bottom and after that I have to multiply every vertex of every mesh by its final transformation matrix. So I have this: public void calculeFinalMatrixPosition(Bone boneParent, Bone bone) { System.out.println("-->" + bone.name); if (boneParent != null) { bone.matrixCombined = bone.matrixTransform.multiply(boneParent.matrixCombined); } else { bone.matrixCombined = bone.matrixTransform; } bone.matrixFinal = bone.matrixCombined; for (Bone childBone : bone.boneChilds) { calculeFinalMatrixPosition(bone, childBone); } } Then I have to multiply every vertex of the mesh: public void transformVertex(Bone bone) { for (Iterator<Mesh> iterator = meshes.iterator(); iterator.hasNext();) { Mesh mesh = iterator.next(); if (mesh.boneName.equals(bone.name)) { float[] vertex = new float[4]; double[] newVertex = new double[3]; if (mesh.skinnedVertexBuffer == null) { mesh.skinnedVertexBuffer = new FloatDataBuffer( mesh.numVertices, 3); } mesh.vertexBuffer.buffer.rewind(); while (mesh.vertexBuffer.buffer.hasRemaining()) { vertex[0] = mesh.vertexBuffer.buffer.get(); vertex[1] = mesh.vertexBuffer.buffer.get(); vertex[2] = mesh.vertexBuffer.buffer.get(); vertex[3] = 1; newVertex = bone.matrixFinal.transpose().multiply(vertex); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[0])); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[1])); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[2])); } mesh.vertexBuffer = new FloatDataBuffer( mesh.numVertices, 3); mesh.skinnedVertexBuffer.buffer.rewind(); mesh.vertexBuffer.buffer.put(mesh.skinnedVertexBuffer.buffer); } } for (Bone childBone : bone.boneChilds) { transformVertex(childBone); } } I know this is not the more efficient code but by now I just want to understand exactly how a hierarchical model is organized and how I can draw it on the screen. Thanks in advance for your help.

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• Can one draw a cube using different method/drawing mode?

  - by den-javamaniac

  Hi. I've just started learning gamedev (in particular android EGL based) and have ran over a code from Pro Android Games 2 that looks as follows: /* * Copyright (C) 2007 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package opengl.scenes.cubes; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.IntBuffer; import javax.microedition.khronos.opengles.GL10; public class Cube { public Cube(){ int one = 0x10000; int vertices[] = { -one, -one, -one, one, -one, -one, one, one, -one, -one, one, -one, -one, -one, one, one, -one, one, one, one, one, -one, one, one, }; int colors[] = { 0, 0, 0, one, one, 0, 0, one, one, one, 0, one, 0, one, 0, one, 0, 0, one, one, one, 0, one, one, one, one, one, one, 0, one, one, one, }; byte indices[] = { 0, 4, 5, 0, 5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7, 3, 3, 7, 4, 3, 4, 0, 4, 7, 6, 4, 6, 5, 3, 0, 1, 3, 1, 2 }; // Buffers to be passed to gl*Pointer() functions // must be direct, i.e., they must be placed on the // native heap where the garbage collector cannot vbb.asIntBuffer() // move them. // // Buffers with multi-byte datatypes (e.g., short, int, float) // must have their byte order set to native order ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4); vbb.order(ByteOrder.nativeOrder()); mVertexBuffer = vbb.asIntBuffer(); mVertexBuffer.put(vertices); mVertexBuffer.position(0); ByteBuffer cbb = ByteBuffer.allocateDirect(colors.length*4); cbb.order(ByteOrder.nativeOrder()); mColorBuffer = cbb.asIntBuffer(); mColorBuffer.put(colors); mColorBuffer.position(0); mIndexBuffer = ByteBuffer.allocateDirect(indices.length); mIndexBuffer.put(indices); mIndexBuffer.position(0); } public void draw(GL10 gl) { gl.glFrontFace(GL10.GL_CW); gl.glVertexPointer(3, GL10.GL_FIXED, 0, mVertexBuffer); gl.glColorPointer(4, GL10.GL_FIXED, 0, mColorBuffer); gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE, mIndexBuffer); } private IntBuffer mVertexBuffer; private IntBuffer mColorBuffer; private ByteBuffer mIndexBuffer;} So it suggests to draw a cube using triangles. My question is: can I draw the same cube using GL_TPOLYGON? If so, isn't that an easier/more understandable way to do things?

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• runtime error: invalid memory address or nil pointer dereference

  - by Klink

  I want to learn OpenGL 3.0 with golang. But when i try to compile some code, i get many errors. package main import ( "os" //"errors" "fmt" //gl "github.com/chsc/gogl/gl33" //"github.com/jteeuwen/glfw" "github.com/go-gl/gl" "github.com/go-gl/glfw" "runtime" "time" ) var ( width int = 640 height int = 480 ) var ( points = []float32{0.0, 0.8, -0.8, -0.8, 0.8, -0.8} ) func initScene() { gl.Init() gl.ClearColor(0.0, 0.5, 1.0, 1.0) gl.Enable(gl.CULL_FACE) gl.Viewport(0, 0, 800, 600) } func glfwInitWindowContext() { if err := glfw.Init(); err != nil { fmt.Fprintf(os.Stderr, "glfw_Init: %s\n", err) glfw.Terminate() } glfw.OpenWindowHint(glfw.FsaaSamples, 1) glfw.OpenWindowHint(glfw.WindowNoResize, 1) if err := glfw.OpenWindow(width, height, 0, 0, 0, 0, 32, 0, glfw.Windowed); err != nil { fmt.Fprintf(os.Stderr, "glfw_Window: %s\n", err) glfw.CloseWindow() } glfw.SetSwapInterval(1) glfw.SetWindowTitle("Title") } func drawScene() { for glfw.WindowParam(glfw.Opened) == 1 { gl.Clear(gl.COLOR_BUFFER_BIT) vertexShaderSrc := `#version 120 attribute vec2 coord2d; void main(void) { gl_Position = vec4(coord2d, 0.0, 1.0); }` vertexShader := gl.CreateShader(gl.VERTEX_SHADER) vertexShader.Source(vertexShaderSrc) vertexShader.Compile() fragmentShaderSrc := `#version 120 void main(void) { gl_FragColor[0] = 0.0; gl_FragColor[1] = 0.0; gl_FragColor[2] = 1.0; }` fragmentShader := gl.CreateShader(gl.FRAGMENT_SHADER) fragmentShader.Source(fragmentShaderSrc) fragmentShader.Compile() program := gl.CreateProgram() program.AttachShader(vertexShader) program.AttachShader(fragmentShader) program.Link() attribute_coord2d := program.GetAttribLocation("coord2d") program.Use() //attribute_coord2d.AttribPointer(size, typ, normalized, stride, pointer) attribute_coord2d.EnableArray() attribute_coord2d.AttribPointer(0, 3, false, 0, &(points[0])) //gl.DrawArrays(gl.TRIANGLES, 0, len(points)) gl.DrawArrays(gl.TRIANGLES, 0, 3) glfw.SwapBuffers() inputHandler() time.Sleep(100 * time.Millisecond) } } func inputHandler() { glfw.Enable(glfw.StickyKeys) if glfw.Key(glfw.KeyEsc) == glfw.KeyPress { //gl.DeleteBuffers(2, &uiVBO[0]) glfw.Terminate() } if glfw.Key(glfw.KeyF2) == glfw.KeyPress { glfw.SetWindowTitle("Title2") fmt.Println("Changed to 'Title2'") fmt.Println(len(points)) } if glfw.Key(glfw.KeyF1) == glfw.KeyPress { glfw.SetWindowTitle("Title1") fmt.Println("Changed to 'Title1'") } } func main() { runtime.LockOSThread() glfwInitWindowContext() initScene() drawScene() } And after that: panic: runtime error: invalid memory address or nil pointer dereference [signal 0xb code=0x1 addr=0x0 pc=0x41bc6f74] goroutine 1 [syscall]: github.com/go-gl/gl._Cfunc_glDrawArrays(0x4, 0x7f8500000003) /tmp/go-build463568685/github.com/go-gl/gl/_obj/_cgo_defun.c:610 +0x2f github.com/go-gl/gl.DrawArrays(0x4, 0x3, 0x0, 0x45bd70) /tmp/go-build463568685/github.com/go-gl/gl/_obj/gl.cgo1.go:1922 +0x33 main.drawScene() /home/klink/Dev/Go/gogl/gopher/exper.go:85 +0x1e6 main.main() /home/klink/Dev/Go/gogl/gopher/exper.go:116 +0x27 goroutine 2 [syscall]: created by runtime.main /build/buildd/golang-1/src/pkg/runtime/proc.c:221 exit status 2

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• Engine Rendering pipeline : Making shaders generic

  - by fakhir

  I am trying to make a 2D game engine using OpenGL ES 2.0 (iOS for now). I've written Application layer in Objective C and a separate self contained RendererGLES20 in C++. No GL specific call is made outside the renderer. It is working perfectly. But I have some design issues when using shaders. Each shader has its own unique attributes and uniforms that need to be set just before the main draw call (glDrawArrays in this case). For instance, in order to draw some geometry I would do: void RendererGLES20::render(Model * model) { // Set a bunch of uniforms glUniformMatrix4fv(.......); // Enable specific attributes, can be many glEnableVertexAttribArray(......); // Set a bunch of vertex attribute pointers: glVertexAttribPointer(positionSlot, 2, GL_FLOAT, GL_FALSE, stride, m->pCoords); // Now actually Draw the geometry glDrawArrays(GL_TRIANGLES, 0, m->vertexCount); // After drawing, disable any vertex attributes: glDisableVertexAttribArray(.......); } As you can see this code is extremely rigid. If I were to use another shader, say ripple effect, i would be needing to pass extra uniforms, vertex attribs etc. In other words I would have to change the RendererGLES20 render source code just to incorporate the new shader. Is there any way to make the shader object totally generic? Like What if I just want to change the shader object and not worry about game source re-compiling? Any way to make the renderer agnostic of uniforms and attributes etc?. Even though we need to pass data to uniforms, what is the best place to do that? Model class? Is the model class aware of shader specific uniforms and attributes? Following shows Actor class: class Actor : public ISceneNode { ModelController * model; AIController * AI; }; Model controller class: class ModelController { class IShader * shader; int textureId; vec4 tint; float alpha; struct Vertex * vertexArray; }; Shader class just contains the shader object, compiling and linking sub-routines etc. In Game Logic class I am actually rendering the object: void GameLogic::update(float dt) { IRenderer * renderer = g_application->GetRenderer(); Actor * a = GetActor(id); renderer->render(a->model); } Please note that even though Actor extends ISceneNode, I haven't started implementing SceneGraph yet. I will do that as soon as I resolve this issue. Any ideas how to improve this? Related design patterns etc? Thank you for reading the question.

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• How do I apply skeletal animation from a .x (Direct X) file?

  - by Byte56

  Using the .x format to export a model from Blender, I can load a mesh, armature and animation. I have no problems generating the mesh and viewing models in game. Additionally, I have animations and the armature properly loaded into appropriate data structures. My problem is properly applying the animation to the models. I have the framework for applying the models and the code for selecting animations and stepping through frames. From what I understand, the AnimationKeys inside the AnimationSet supplies the transformations to transform the bind pose to the pose in the animated frame. As small example: Animation { {Armature_001_Bone} AnimationKey { 2; //Position 121; //number of frames 0;3; 0.000000, 0.000000, 0.000000;;, 1;3; 0.000000, 0.000000, 0.005524;;, 2;3; 0.000000, 0.000000, 0.022217;;, ... } AnimationKey { 0; //Quaternion Rotation 121; 0;4; -0.707107, 0.707107, 0.000000, 0.000000;;, 1;4; -0.697332, 0.697332, 0.015710, 0.015710;;, 2;4; -0.684805, 0.684805, 0.035442, 0.035442;;, ... } AnimationKey { 1; //Scale 121; 0;3; 1.000000, 1.000000, 1.000000;;, 1;3; 1.000000, 1.000000, 1.000000;;, 2;3; 1.000000, 1.000000, 1.000000;;, ... } } So, to apply frame 2, I would take the position, rotation and scale from frame 2, create a transformation matrix (call it Transform_A) from them and apply that matrix the vertices controlled by Armature_001_Bone at their weights. So I'd stuff TransformA into my shader and transform the vertex. Something like: vertexPos = vertexPos * bones[ int(bfs_BoneIndices.x) ] * bfs_BoneWeights.x; Where bfs_BoneIndices and bfs_BoneWeights are values specific to the current vertex. When loading in the mesh vertices, I transform them by the rootTransform and the meshTransform. This ensures they're oriented and scaled correctly for viewing the bind pose. The problem is when I create that transformation matrix (using the position, rotation and scale from the animation), it doesn't properly transform the vertex. There's likely more to it than just using the animation data. I also tried applying the bone transform hierarchies, still no dice. Basically I end up with some twisted models. It should also be noted that I'm working in openGL, so any matrix transposes that might need to be applied should be considered. What data do I need and how do I combine it for applying .x animations to models?

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• Unexpected results for projection on to plane

  - by ravenspoint

  I want to use this projection matrix: GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; It should cast object shadows onto the y = 0 plane from a point light at 1,1,-1. I create a rectangle in the x = 0.5 plane glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); Now if I manually multiply these vertices with the matrix, I get. glBegin( GL_QUADS ); glVertex3f( 0.375,0,-0.375); glVertex3f( 0.375,0,-1.625); glVertex3f( 0,0,-2); glVertex3f( 0,0,0); glEnd(); Which produces a reasonable display ( camera at 0,5,0 looking down y axis ) So rather than do the calculation manually, I should be able to use the opengl model transormation. I write this code: glMatrixMode (GL_MODELVIEW); GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; glLoadMatrixf( shadow ); glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); But this produces a blank screen! What am I doing wrong? Is there some debug mode where I can print out the transformed vertices, so I can see where they are ending up? Note: People have suggested that using glMultMatrixf() might make a difference. It doesn't. Replacing glLoadMatrixf( shadow ); with glLoadIdentity(); glMultMatrixf( shadow ); gives the identical result ( of course! )

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• cocos2d-x simple shader usage [on hold]

  - by Narek

  I want to obtain color ramp effect from this tutorial: http://www.raywenderlich.com/10862/how-to-create-cool-effects-with-custom-shaders-in-opengl-es-2-0-and-cocos2d-2-x Here is my code in cocos2d-x 3: bool HelloWorld::init() { ////////////////////////////// // 1. super init first if ( !Layer::init() ) { return false; } Vec2 origin = Director::getInstance()->getVisibleOrigin(); sprite = Sprite::create("HelloWorld.png"); sprite->setAnchorPoint(Vec2(0, 0)); sprite->setRotation(3); sprite->setPosition(origin); addChild(sprite); std::string str = FileUtils::getInstance()->getStringFromFile("CSEColorRamp.fsh"); const GLchar * fragmentSource = str.c_str(); GLProgram* p = GLProgram::createWithByteArrays(ccPositionTextureA8Color_vert, fragmentSource); p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_POSITION, GLProgram::VERTEX_ATTRIB_POSITION); p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_TEX_COORD, GLProgram::VERTEX_ATTRIB_TEX_COORD); p->link(); p->updateUniforms(); sprite->setGLProgram(p); // 3 colorRampUniformLocation = glGetUniformLocation(sprite->getGLProgram()->getProgram(), "u_colorRampTexture"); glUniform1i(colorRampUniformLocation, 1); // 4 colorRampTexture = Director::getInstance()->getTextureCache()->addImage("colorRamp.png"); colorRampTexture->setAliasTexParameters(); // 5 sprite->getGLProgram()->use(); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, colorRampTexture->getName()); glActiveTexture(GL_TEXTURE0); return true; } And here is the fragment shader as it is in the tutorial: #ifdef GL_ES precision mediump float; #endif // 1 varying vec2 v_texCoord; uniform sampler2D u_texture; uniform sampler2D u_colorRampTexture; void main() { // 2 vec3 normalColor = texture2D(u_texture, v_texCoord).rgb; // 3 float rampedR = texture2D(u_colorRampTexture, vec2(normalColor.r, 0)).r; float rampedG = texture2D(u_colorRampTexture, vec2(normalColor.g, 0)).g; float rampedB = texture2D(u_colorRampTexture, vec2(normalColor.b, 0)).b; // 4 gl_FragColor = vec4(rampedR, rampedG, rampedB, 1); } As a result I get a black screen with 2 draw calls. What is wrong? Do I miss something?

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• Quaternion based rotation and pivot position

  - by Michael IV

  I can't figure out how to perform matrix rotation using Quaternion while taking into account pivot position in OpenGL.What I am currently getting is rotation of the object around some point in the space and not a local pivot which is what I want. Here is the code [Using Java] Quaternion rotation method: public void rotateTo3(float xr, float yr, float zr) { _rotation.x = xr; _rotation.y = yr; _rotation.z = zr; Quaternion xrotQ = Glm.angleAxis((xr), Vec3.X_AXIS); Quaternion yrotQ = Glm.angleAxis((yr), Vec3.Y_AXIS); Quaternion zrotQ = Glm.angleAxis((zr), Vec3.Z_AXIS); xrotQ = Glm.normalize(xrotQ); yrotQ = Glm.normalize(yrotQ); zrotQ = Glm.normalize(zrotQ); Quaternion acumQuat; acumQuat = Quaternion.mul(xrotQ, yrotQ); acumQuat = Quaternion.mul(acumQuat, zrotQ); Mat4 rotMat = Glm.matCast(acumQuat); _model = new Mat4(1); scaleTo(_scaleX, _scaleY, _scaleZ); _model = Glm.translate(_model, new Vec3(_pivot.x, _pivot.y, 0)); _model =rotMat.mul(_model);//_model.mul(rotMat); //rotMat.mul(_model); _model = Glm.translate(_model, new Vec3(-_pivot.x, -_pivot.y, 0)); translateTo(_x, _y, _z); notifyTranformChange(); } Model matrix scale method: public void scaleTo(float x, float y, float z) { _model.set(0, x); _model.set(5, y); _model.set(10, z); _scaleX = x; _scaleY = y; _scaleZ = z; notifyTranformChange(); } Translate method: public void translateTo(float x, float y, float z) { _x = x - _pivot.x; _y = y - _pivot.y; _z = z; _position.x = _x; _position.y = _y; _position.z = _z; _model.set(12, _x); _model.set(13, _y); _model.set(14, _z); notifyTranformChange(); } But this method in which I don't use Quaternion works fine: public void rotate(Vec3 axis, float angleDegr) { _rotation.add(axis.scale(angleDegr)); // change to GLM: Mat4 backTr = new Mat4(1.0f); backTr = Glm.translate(backTr, new Vec3(_pivot.x, _pivot.y, 0)); backTr = Glm.rotate(backTr, angleDegr, axis); backTr = Glm.translate(backTr, new Vec3(-_pivot.x, -_pivot.y, 0)); _model =_model.mul(backTr);///backTr.mul(_model); notifyTranformChange(); }

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• Creating a voxel chunk with a VBO - How to translate the coordinates of each block and add it to the VBO chunk?

  - by sunsunsunsunsun

  Im trying to make a voxel engine similar to minecraft as a little learning experience and a way to learn some opengl. I have created a chunk class and I want to put all of the vertices for the whole chunk into a single VBO. I was previously only putting each block into a vbo and making a call to render each block. Anyways, I am a bit confused about how I can translate the coordinates of each block in the chunk when I'm putting all vertices into one vbo. This is what I have at the moment. public void putVertices(float tx, float ty, float tz) { float l_length = 1.0f; float l_height = 1.0f; float l_width = 1.0f; vertexPositionData.put(new float[]{ xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, l_height + ty,zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + l_width + tz, xOffset + l_length + tx, l_height + ty,zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz }); } public void createChunk() { vertexPositionData = BufferUtils.createFloatBuffer((24*3)*activateBlocks); Random random = new Random(); for (int x = 0; x < CHUNK_SIZE; x++) { for (int y = 0; y < CHUNK_SIZE; y++) { for (int z = 0; z < CHUNK_SIZE; z++) { if(blocks[x][y][z].getActive()) { putVertices(x*2.0f, y*2.0f, z*2.0f); } } } } Whats any easy way to translate the vertices of each block into its correct position? I was previously using glTranslatef with each call to render block but this wont work now. What I am doing now also does not work, the blocks all render in stacks on top of each other and it looks like this: http://i.imgur.com/NyFtBTI.png Thanks

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• Open GL polygons not displaying

  - by Darestium

  I have tried to follow nehe's opengl tutorial lesson 2. I use sfml for my window creation. The problem I have is that both the triangle and the quad don't show up on the screen: #include <SFML/System.hpp> #include <SFML/Window.hpp> #include <iostream> void processEvents(sf::Window *app); void processInput(sf::Window *app, const sf::Input &input); void renderCube(sf::Window *app, sf::Clock *clock); void renderGlScene(sf::Window *app); void init(); int main() { sf::Window app(sf::VideoMode(800, 600, 32), "Nehe Lesson 2"); app.UseVerticalSync(false); init(); while (app.IsOpened()) { processEvents(&app); renderGlScene(&app); app.Display(); } return EXIT_SUCCESS; } void init() { glClearDepth(1.f); glClearColor(0.f, 0.f, 0.f, 0.f); // Enable z-buffer and read and write glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); // Setup a perpective projection glMatrixMode(GL_MODELVIEW); glLoadIdentity(); gluPerspective(45.f, 1.f, 1.f, 500.f); glShadeModel(GL_SMOOTH); } void processEvents(sf::Window *app) { sf::Event event; while (app->GetEvent(event)) { if (event.Type == sf::Event::Closed) { app->Close(); } if (event.Type == sf::Event::KeyPressed && event.Key.Code == sf::Key::Escape) { app->Close(); } } } void renderGlScene(sf::Window *app) { app->SetActive(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the screen and the depth buffer glLoadIdentity(); // Reset the view glTranslatef(-1.5f, 0.0f, -6.0f); // Move Left 1.5 units and into the screen 6.0 glBegin(GL_TRIANGLES); glVertex3f( 0.0f, 1.0f, 0.0f); // Top glVertex3f(-1.0,-1.0f, 0.0f); // Bottom Left glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right glEnd(); glTranslatef(3.0f, 0.0f, 0.0f); glBegin(GL_QUADS); // Draw a quad glVertex3f(-1.0f, 1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f); glEnd(); } I would greatly appreciate it if someone could help me resolve my issue.

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• Rending 2D Tile World (With Player In The Middle)

  - by Mick

  What I have at the moment is a series of data structures I'm using, and I would like to render the world onto the screen (just the visible parts). I've actually already done this several times (lots of rewrites), but it's a bit buggy (rounding seems to make the screen jump ever so slightly every x tiles the player walks past). Basically I've been confusing myself heavily on what I feel should be a pretty simple problem... so here I am asking for some help! OK! So I have a 50x50 array holding the tiles of the world. I have the player position as 2 floats, x ([0, 49]) and y ([0, 49]) in that array. I have the application size exactly in pixels (x and y). I have an arbitrary TILE_SIZE static int (based on screen pixels). What I think is heavily confusing me is using a 2d orthogonal projection in opengl which maps (0,0) to the top left of the screen and (SCREEN_SIZE_X, SCREEN_SIZE_Y) to the bottom right of the screen. gl.glMatrixMode(GL.GL_PROJECTION); gl.glLoadIdentity(); glu.gluOrtho2D(0, getActualWidth(), getActualHeight(), 0); gl.glMatrixMode(GL.GL_MODELVIEW); gl.glLoadIdentity(); The map tiles are set so that the (0,0) in the array is the bottom left. And the player has to be in the middle on the screen (SCREEN_SIZE_X/2, SCREEN_SIZE_Y/2). What I've been doing so far is trying to render 1-2 tiles more all around what would be displayed on the screen so that I don't have to worry about figuring out rendering half a tile from the top left, depending where the player is. It seems like such an easy problem but after spending about 40+hours on it rewriting it many times I think I'm at a point where I just can't think clearly anymore... Any help would be appreciated. It would be great if someone can provide some very basic pseudo code on keeping the player in the middle when your projection is mapped to screen coordinates and only rendering basically the tiles that you would be any be see. Thanks!

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• When should I use indexed arrays of OpenGL vertices?

  - by Tartley

  I'm trying to get a clear idea of when I should be using indexed arrays of OpenGL vertices, drawn with gl[Multi]DrawElements and the like, versus when I should simply use contiguous arrays of vertices, drawn with gl[Multi]DrawArrays. (Update: The consensus in the replies I got is that one should always be using indexed vertices.) I have gone back and forth on this issue several times, so I'm going to outline my current understanding, in the hopes someone can either tell me I'm now finally more or less correct, or else point out where my remaining misunderstandings are. Specifically, I have three conclusions, in bold. Please correct them if they are wrong. One simple case is if my geometry consists of meshes to form curved surfaces. In this case, the vertices in the middle of the mesh will have identical attributes (position, normal, color, texture coord, etc) for every triangle which uses the vertex. This leads me to conclude that: 1. For geometry with few seams, indexed arrays are a big win. Follow rule 1 always, except: For geometry that is very 'blocky', in which every edge represents a seam, the benefit of indexed arrays is less obvious. To take a simple cube as an example, although each vertex is used in three different faces, we can't share vertices between them, because for a single vertex, the surface normals (and possible other things, like color and texture co-ord) will differ on each face. Hence we need to explicitly introduce redundant vertex positions into our array, so that the same position can be used several times with different normals, etc. This means that indexed arrays are of less use. e.g. When rendering a single face of a cube: 0 1 o---o |\ | | \ | | \| o---o 3 2 (this can be considered in isolation, because the seams between this face and all adjacent faces mean than none of these vertices can be shared between faces) if rendering using GL_TRIANGLE_FAN (or _STRIP), then each face of the cube can be rendered thus: verts = [v0, v1, v2, v3] colors = [c0, c0, c0, c0] normal = [n0, n0, n0, n0] Adding indices does not allow us to simplify this. From this I conclude that: 2. When rendering geometry which is all seams or mostly seams, when using GL_TRIANGLE_STRIP or _FAN, then I should never use indexed arrays, and should instead always use gl[Multi]DrawArrays. (Update: Replies indicate that this conclusion is wrong. Even though indices don't allow us to reduce the size of the arrays here, they should still be used because of other performance benefits, as discussed in the comments) The only exception to rule 2 is: When using GL_TRIANGLES (instead of strips or fans), then half of the vertices can still be re-used twice, with identical normals and colors, etc, because each cube face is rendered as two separate triangles. Again, for the same single cube face: 0 1 o---o |\ | | \ | | \| o---o 3 2 Without indices, using GL_TRIANGLES, the arrays would be something like: verts = [v0, v1, v2, v2, v3, v0] normals = [n0, n0, n0, n0, n0, n0] colors = [c0, c0, c0, c0, c0, c0] Since a vertex and a normal are often 3 floats each, and a color is often 3 bytes, that gives, for each cube face, about: verts = 6 * 3 floats = 18 floats normals = 6 * 3 floats = 18 floats colors = 6 * 3 bytes = 18 bytes = 36 floats and 18 bytes per cube face. (I understand the number of bytes might change if different types are used, the exact figures are just for illustration.) With indices, we can simplify this a little, giving: verts = [v0, v1, v2, v3] (4 * 3 = 12 floats) normals = [n0, n0, n0, n0] (4 * 3 = 12 floats) colors = [c0, c0, c0, c0] (4 * 3 = 12 bytes) indices = [0, 1, 2, 2, 3, 0] (6 shorts) = 24 floats + 12 bytes, and maybe 6 shorts, per cube face. See how in the latter case, vertices 0 and 2 are used twice, but only represented once in each of the verts, normals and colors arrays. This sounds like a small win for using indices, even in the extreme case of every single geometry edge being a seam. This leads me to conclude that: 3. When using GL_TRIANGLES, one should always use indexed arrays, even for geometry which is all seams. Please correct my conclusions in bold if they are wrong.

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• How to manipulate the GL.bindframebuffer to target to bind GL_EXT_framebuffer

  - by Alan

  I'm trying to change the framebuffer object from GL_ARB_framebuffer and force it to use GL_EXT_framebuffer since my system is not compatible with the first one. Where in the solution do I need to implement this and how? more information on my problem whenever I create a new Windows OpenGL project from Visual Studio using MonoGame i get the error "cannot find entry point in glbindframebuffer in opengl32.dll" since the framebuffer it uses is GL_ARB_framebuffer which is only supported in Opengl 3 so in a github post i read Gihub post where they suggest this patch that in order to patch you need to force the frame buffers to use GL_EXT_framebuffer but I dont know how to force them to use the EXT instead of the ARB , btw Im using Opengl v2 Mobile intel 4 series card, which is Opengl v2 and ARB needs Opengl v3.

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• Tutoriel VBA/VB6 : Les extensions OpenGL en VBA et VB6, par Thierry Gasperment (Arkham46)

  Bonjour à tous! Voici un article sur la programmation des extensions OpenGL, en VB6/VBA Cet article décrit l'utilisation de quelques extensions fréquemment utilisées : - Les VBO (vertex buffer objects) pour améliorer les performances - Les textures 3D pour réaliser des textures continue sur un volume - Les shaders, largement utilisés pour programmer des effets graphiques Les exemples développés sont assez simples, mais ouvrent la porte à de nombreuses possibilités en 3D sous Visual Basic. Vous pouvez ajoutez vos commentaires sur cet articles à la suite de ce message.

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• Basic tutorial/introduction for 3d matrices, idealy in c++, without openGl or directX

  - by René Nyffenegger

  I am wondering if there is a simple tutorial that covers the basics of how to initialize rotation, translation and projection matrices, and how to multiply them, and how to get the screen coordinates afterwards for a 3d point. Idealy, the tutorial comes with compilable code and is not dependent on any 3rd party library. Searching the internet, I found lots of tutorials, so this is not the problem. Yet, it seemed all of these either covered openGl or directX, or they were theoretical in nature.

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• GLSL Shader Texture Performance

  - by Austin

  I currently have a project that renders OpenGL video using a vertex and fragment shader. The shaders work fine as-is, but in trying to add in texturing, I am running into performance issues and can't figure out why. Before adding texturing, my program ran just fine and loaded my CPU between 0%-4%. When adding texturing (specifically textures AND color -- noted by comment below), my CPU is 100% loaded. The only code I have added is the relevant texturing code to the shader, and the "glBindTexture()" calls to the rendering code. Here are my shaders and relevant rending code. Vertex Shader: #version 150 uniform mat4 mvMatrix; uniform mat4 mvpMatrix; uniform mat3 normalMatrix; uniform vec4 lightPosition; uniform float diffuseValue; layout(location = 0) in vec3 vertex; layout(location = 1) in vec3 color; layout(location = 2) in vec3 normal; layout(location = 3) in vec2 texCoord; smooth out VertData { vec3 color; vec3 normal; vec3 toLight; float diffuseValue; vec2 texCoord; } VertOut; void main(void) { gl_Position = mvpMatrix * vec4(vertex, 1.0); VertOut.normal = normalize(normalMatrix * normal); VertOut.toLight = normalize(vec3(mvMatrix * lightPosition - gl_Position)); VertOut.color = color; VertOut.diffuseValue = diffuseValue; VertOut.texCoord = texCoord; } Fragment Shader: #version 150 smooth in VertData { vec3 color; vec3 normal; vec3 toLight; float diffuseValue; vec2 texCoord; } VertIn; uniform sampler2D tex; layout(location = 0) out vec3 colorOut; void main(void) { float diffuseComp = max( dot(normalize(VertIn.normal), normalize(VertIn.toLight)) ), 0.0); vec4 color = texture2D(tex, VertIn.texCoord); colorOut = color.rgb * diffuseComp * VertIn.diffuseValue + color.rgb * (1 - VertIn.diffuseValue); // FOLLOWING LINE CAUSES PERFORMANCE ISSUES colorOut *= VertIn.color; } Relevant Rendering Code: // 3 textures have been successfully pre-loaded, and can be used // texture[0] is a 1x1 white texture to effectively turn off texturing glUseProgram(program); // Draw squares glBindTexture(GL_TEXTURE_2D, texture[1]); // Set attributes, uniforms, etc glDrawArrays(GL_QUADS, 0, 6*4); // Draw triangles glBindTexture(GL_TEXTURE_2D, texture[0]); // Set attributes, uniforms, etc glDrawArrays(GL_TRIANGLES, 0, 3*4); // Draw reference planes glBindTexture(GL_TEXTURE_2D, texture[0]); // Set attributes, uniforms, etc glDrawArrays(GL_LINES, 0, 4*81*2); // Draw terrain glBindTexture(GL_TEXTURE_2D, texture[2]); // Set attributes, uniforms, etc glDrawArrays(GL_TRIANGLES, 0, 501*501*6); // Release glBindTexture(GL_TEXTURE_2D, 0); glUseProgram(0); Any help is greatly appreciated!

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• Problems with 3D Array for Voxel Data

  - by Sean M.

  I'm trying to implement a voxel engine in C++ using OpenGL, and I've been working on the rendering of the world. In order to render, I have a 3D array of uint16's that hold that id of the block at the point. I also have a 3D array of uint8's that I am using to store the visibility data for that point, where each bit represents if a face is visible. I have it so the blocks render and all of the proper faces are hidden if needed, but all of the blocks are offset by a power of 2 from where they are stored in the array. So the block at [0][0][0] is rendered at (0, 0, 0), and the block at 11 is rendered at (1, 1, 1), but the block at [2][2][2] is rendered at (4, 4, 4) and the block at [3][3][3] is rendered at (8, 8, 8), and so on and so forth. This is the result of drawing the above situation: I'm still a little new to the more advanced concepts of C++, like triple pointers, which I'm using for the 3D array, so I think the error is somewhere in there. This is the code for creating the arrays: uint16*** _blockData; //Contains a 3D array of uint16s that are the ids of the blocks in the region uint8*** _visibilityData; //Contains a 3D array of bytes that hold the visibility data for the faces //Allocate memory for the world data _blockData = new uint16**[REGION_DIM]; for (int i = 0; i < REGION_DIM; i++) { _blockData[i] = new uint16*[REGION_DIM]; for (int j = 0; j < REGION_DIM; j++) _blockData[i][j] = new uint16[REGION_DIM]; } //Allocate memory for the visibility _visibilityData = new uint8**[REGION_DIM]; for (int i = 0; i < REGION_DIM; i++) { _visibilityData[i] = new uint8*[REGION_DIM]; for (int j = 0; j < REGION_DIM; j++) _visibilityData[i][j] = new uint8[REGION_DIM]; } Here is the code used to create the block mesh for the region: //Check if the positive x face is visible, this happens for every face //Block::VERT_X_POS is just an array of non-transformed cube verts for one face //These checks are in a triple loop, which goes over every place in the array if (_visibilityData[x][y][z] & 0x01 > 0) { _vertexData->AddData(&(translateVertices(Block::VERT_X_POS, x, y, z)[0]), sizeof(Block::VERT_X_POS)); } //This is a seperate method, not in the loop glm::vec3* translateVertices(const glm::vec3 data[], uint16 x, uint16 y, uint16 z) { glm::vec3* copy = new glm::vec3[6]; memcpy(&copy, &data, sizeof(data)); for(int i = 0; i < 6; i++) copy[i] += glm::vec3(x, -y, z); //Make +y go down instead return copy; } I cannot see where the blocks may be getting offset by more than they should be, and certainly not why the offsets are a power of 2. Any help is greatly appreciated. Thanks.

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• How to translate along Z axis in OpenTK

  - by JeremyJAlpha

  I am playing around with an OpenGL sample application I downloaded for Xamarin-Android. The sample application produces a rotating colored cube I would simply like to edit it so that the rotating cube is translated along the Z axis and disappears into the distance. I modified the code by: adding an cumulative variable to store my Z distance, adding GL.Enable(All.DepthBufferBit) - unsure if I put it in the right place, adding GL.Translate(0.0f, 0.0f, Depth) - before the rotate functions, Result: cube rotates a couple of times then disappears, it seems to be getting clipped out of the frustum. So my question is what is the correct way to use and initialize the Z buffer and get the cube to travel along the Z axis? I am sure I am missing some function calls but am unsure of what they are and where to put them. I apologise in advance as this is very basic stuff but am still learning :P, I would appreciate it if anyone could show me the best way to get the cube to still rotate but to also move along the Z axis. I have commented all my modifications in the code: // This gets called when the drawing surface is ready protected override void OnLoad (EventArgs e) { // this call is optional, and meant to raise delegates // in case any are registered base.OnLoad (e); // UpdateFrame and RenderFrame are called // by the render loop. This is takes effect // when we use 'Run ()', like below UpdateFrame += delegate (object sender, FrameEventArgs args) { // Rotate at a constant speed for (int i = 0; i < 3; i ++) rot [i] += (float) (rateOfRotationPS [i] * args.Time); }; RenderFrame += delegate { RenderCube (); }; GL.Enable(All.DepthBufferBit); //Added by Noob GL.Enable(All.CullFace); GL.ShadeModel(All.Smooth); GL.Hint(All.PerspectiveCorrectionHint, All.Nicest); // Run the render loop Run (30); } void RenderCube () { GL.Viewport(0, 0, viewportWidth, viewportHeight); GL.MatrixMode (All.Projection); GL.LoadIdentity (); if ( viewportWidth > viewportHeight ) { GL.Ortho(-1.5f, 1.5f, 1.0f, -1.0f, -1.0f, 1.0f); } else { GL.Ortho(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f); } GL.MatrixMode (All.Modelview); GL.LoadIdentity (); Depth -= 0.02f; //Added by Noob GL.Translate(0.0f,0.0f,Depth); //Added by Noob GL.Rotate (rot[0], 1.0f, 0.0f, 0.0f); GL.Rotate (rot[1], 0.0f, 1.0f, 0.0f); GL.Rotate (rot[2], 0.0f, 1.0f, 0.0f); GL.ClearColor (0, 0, 0, 1.0f); GL.Clear (ClearBufferMask.ColorBufferBit); GL.VertexPointer(3, All.Float, 0, cube); GL.EnableClientState (All.VertexArray); GL.ColorPointer (4, All.Float, 0, cubeColors); GL.EnableClientState (All.ColorArray); GL.DrawElements(All.Triangles, 36, All.UnsignedByte, triangles); SwapBuffers (); }

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