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• OpenGL/GLSL: Render to cube map?

  - by BobDole

  I'm trying to figure out how to render my scene to a cube map. I've been stuck on this for a bit and figured I would ask you guys for some help. I'm new to OpenGL and this is the first time I'm using a FBO. I currently have a working example of using a cubemap bmp file, and the samplerCube sample type in the fragment shader is attached to GL_TEXTURE1. I'm not changing the shader code at all. I'm just changing the fact that I wont be calling the function that was loading the cubemap bmp file and trying to use the below code to render to a cubemap. You can see below that I'm also attaching the texture again to GL_TEXTURE1. This is so when I set the uniform: glUniform1i(getUniLoc(myProg, "Cubemap"), 1); it can access it in my fragment shader via uniform samplerCube Cubemap. I'm calling the below function like so: cubeMapTexture = renderToCubeMap(150, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE); Now, I realize in the draw loop below that I'm not changing the view direction to look down the +x, -x, +y, -y, +z, -z axis. I really was just wanting to see something working first before implemented that. I figured I should at least see something on my object the way the code is now. I'm not seeing anything, just straight black. I've made my background white still the object is black. I've removed lighting, and coloring to just sample the cubemap texture and still black. I'm thinking the problem might be the format types when setting my texture which is GL_RGB8, GL_RGBA but I've also tried: GL_RGBA, GL_RGBA GL_RGB, GL_RGB I thought this would be standard since we are rendering to a texture attached to a framebuffer, but I've seen different examples that use different enum values. I've also tried binding the cube map texture in every draw call that I'm wanting to use the cube map: glBindTexture(GL_TEXTURE_CUBE_MAP, cubeMapTexture); Also, I'm not creating a depth buffer for the FBO which I saw in most examples, because I'm only wanting the color buffer for my cube map. I actually added one to see if that was the problem and still got the same results. I could of fudged that up when I tried. Any help that can point me in the right direction would be appreciated. GLuint renderToCubeMap(int size, GLenum InternalFormat, GLenum Format, GLenum Type) { // color cube map GLuint textureObject; int face; GLenum status; //glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE1); glGenTextures(1, &textureObject); glBindTexture(GL_TEXTURE_CUBE_MAP, textureObject); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); for (face = 0; face < 6; face++) { glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, InternalFormat, size, size, 0, Format, Type, NULL); } // framebuffer object glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, textureObject, 0); status = glCheckFramebufferStatus(GL_FRAMEBUFFER); printf("%d\"\n", status); printf("%d\n", GL_FRAMEBUFFER_COMPLETE); glViewport(0,0,size, size); for (face = 1; face < 6; face++) { drawSpheres(); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, textureObject, 0); } //Bind 0, which means render to back buffer, as a result, fb is unbound glBindFramebuffer(GL_FRAMEBUFFER, 0); return textureObject; }

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• Simple OpenGL program major slow down at high resolution

  - by Grieverheart

  I have created a small OpenGL 3.3 (Core) program using freeglut. The whole geometry is two boxes and one plane with some textures. I can move around like in an FPS and that's it. The problem is I face a big slow down of fps when I make my window large (i.e. above 1920x1080). I have monitors GPU usage when in full-screen and it shows GPU load of nearly 100% and Memory Controller load of ~85%. When at 600x600, these numbers are at about 45%, my CPU is also at full load. I use deferred rendering at the moment but even when forward rendering, the slow down was nearly as severe. I can't imagine my GPU is not powerful enough for something this simple when I play many games at 1080p (I have a GeForce GT 120M btw). Below are my shaders, First Pass #VS #version 330 core uniform mat4 ModelViewMatrix; uniform mat3 NormalMatrix; uniform mat4 MVPMatrix; uniform float scale; layout(location = 0) in vec3 in_Position; layout(location = 1) in vec3 in_Normal; layout(location = 2) in vec2 in_TexCoord; smooth out vec3 pass_Normal; smooth out vec3 pass_Position; smooth out vec2 TexCoord; void main(void){ pass_Position = (ModelViewMatrix * vec4(scale * in_Position, 1.0)).xyz; pass_Normal = NormalMatrix * in_Normal; TexCoord = in_TexCoord; gl_Position = MVPMatrix * vec4(scale * in_Position, 1.0); } #FS #version 330 core uniform sampler2D inSampler; smooth in vec3 pass_Normal; smooth in vec3 pass_Position; smooth in vec2 TexCoord; layout(location = 0) out vec3 outPosition; layout(location = 1) out vec3 outDiffuse; layout(location = 2) out vec3 outNormal; void main(void){ outPosition = pass_Position; outDiffuse = texture(inSampler, TexCoord).xyz; outNormal = pass_Normal; } Second Pass #VS #version 330 core uniform float scale; layout(location = 0) in vec3 in_Position; void main(void){ gl_Position = mat4(1.0) * vec4(scale * in_Position, 1.0); } #FS #version 330 core struct Light{ vec3 direction; }; uniform ivec2 ScreenSize; uniform Light light; uniform sampler2D PositionMap; uniform sampler2D ColorMap; uniform sampler2D NormalMap; out vec4 out_Color; vec2 CalcTexCoord(void){ return gl_FragCoord.xy / ScreenSize; } vec4 CalcLight(vec3 position, vec3 normal){ vec4 DiffuseColor = vec4(0.0); vec4 SpecularColor = vec4(0.0); vec3 light_Direction = -normalize(light.direction); float diffuse = max(0.0, dot(normal, light_Direction)); if(diffuse 0.0){ DiffuseColor = diffuse * vec4(1.0); vec3 camera_Direction = normalize(-position); vec3 half_vector = normalize(camera_Direction + light_Direction); float specular = max(0.0, dot(normal, half_vector)); float fspecular = pow(specular, 128.0); SpecularColor = fspecular * vec4(1.0); } return DiffuseColor + SpecularColor + vec4(0.1); } void main(void){ vec2 TexCoord = CalcTexCoord(); vec3 Position = texture(PositionMap, TexCoord).xyz; vec3 Color = texture(ColorMap, TexCoord).xyz; vec3 Normal = normalize(texture(NormalMap, TexCoord).xyz); out_Color = vec4(Color, 1.0) * CalcLight(Position, Normal); } Is it normal for the GPU to be used that much under the described circumstances? Is it due to poor performance of freeglut? I understand that the problem could be specific to my code, but I can't paste the whole code here, if you need more info, please tell me.

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• C++ OpenGL wireframe cube rendering blank

  - by caleb.breckon

  I'm just trying to draw a bunch of lines that make up a "cube". I can't for the life of me figure out why this is producing a black screen. The debugger does not break at any point. I'm sure it's a problem with my pointers, as I'm only decent at them in regular c++ and in OpenGL it gets even worse. const char* vertexSource = "#version 150\n" "in vec3 position;" "void main() {" " gl_Position = vec4(position, 1.0);" "}"; const char* fragmentSource = "#version 150\n" "out vec4 outColor;" "void main() {" " outColor = vec4(1.0, 1.0, 1.0, 1.0);" "}"; int main() { initializeGLFW(); // Initialize GLEW glewExperimental = GL_TRUE; glewInit(); // Create Vertex Array Object GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); // Create a Vertex Buffer Object and copy the vertex data to it GLuint vbo; glGenBuffers( 1, &vbo ); float vertices[] = { 1.0f, 1.0f, 1.0f, // Vertex 0 (X, Y, Z) -1.0f, 1.0f, 1.0f, // Vertex 1 (X, Y, Z) -1.0f, -1.0f, 1.0f, // Vertex 2 (X, Y, Z) 1.0f, -1.0f, 1.0f, // Vertex 3 (X, Y, Z) 1.0f, 1.0f, -1.0f, // Vertex 4 (X, Y, Z) -1.0f, 1.0f, -1.0f, // Vertex 5 (X, Y, Z) -1.0f, -1.0f, -1.0f, // Vertex 6 (X, Y, Z) 1.0f, -1.0f, -1.0f // Vertex 7 (X, Y, Z) }; GLuint indices[] = { 0, 1, 1, 2, 2, 3, 3, 0, 4, 5, 5, 6, 6, 7, 7, 4, 0, 4, 1, 5, 2, 6, 3, 7 }; glBindBuffer( GL_ARRAY_BUFFER, vbo ); glBufferData( GL_ARRAY_BUFFER, sizeof( vertices ), vertices, GL_STATIC_DRAW ); //glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vbo); //glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof( indices ), indices, GL_STATIC_DRAW ); // Create and compile the vertex shader GLuint vertexShader = glCreateShader( GL_VERTEX_SHADER ); glShaderSource( vertexShader, 1, &vertexSource, NULL ); glCompileShader( vertexShader ); // Create and compile the fragment shader GLuint fragmentShader = glCreateShader( GL_FRAGMENT_SHADER ); glShaderSource( fragmentShader, 1, &fragmentSource, NULL ); glCompileShader( fragmentShader ); // Link the vertex and fragment shader into a shader program GLuint shaderProgram = glCreateProgram(); glAttachShader( shaderProgram, vertexShader ); glAttachShader( shaderProgram, fragmentShader ); glBindFragDataLocation( shaderProgram, 0, "outColor" ); glLinkProgram (shaderProgram); glUseProgram( shaderProgram); // Specify the layout of the vertex data GLint posAttrib = glGetAttribLocation( shaderProgram, "position" ); glEnableVertexAttribArray( posAttrib ); glVertexAttribPointer( posAttrib, 3, GL_FLOAT, GL_FALSE, 0, 0 ); // Main loop while(glfwGetWindowParam(GLFW_OPENED)) { // Clear the screen to black glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT ); // Draw lines from 2 vertices glDrawElements(GL_LINES, sizeof(indices), GL_UNSIGNED_INT, indices ); // Swap buffers glfwSwapBuffers(); } // Clean up glDeleteProgram( shaderProgram ); glDeleteShader( fragmentShader ); glDeleteShader( vertexShader ); //glDeleteBuffers( 1, &ebo ); glDeleteBuffers( 1, &vbo ); glDeleteVertexArrays( 1, &vao ); glfwTerminate(); exit( EXIT_SUCCESS ); }

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• OpenGl / C++ and some strange light problem on half board

  - by mlodziaszka

  I have some problem with lights in my opengl "game". I have board with is square (-50,50), (50, 50), (50, -50), (-50,-50) x and z since y doesn't matter at all. I tried to make something like flashlight its moving and rotating with camera (me), but when i try to rotate more then 90 degree to left or right it just give diffrend light: http://imageshack.us/photo/my-images/688/lightij.jpg/ (left is spotlight, right point light) There is also a point light in the middle, but its working strange(not like a pointlight) it shines only on half of the board from (-50,50), (50, 50), (50, 0), (-50,-0) x and y: Link to my repo where u can find game exe in download and full code in source: https://bitbucket.org/mlodziaszka/my_game All more fragments of light: float gl_amb[] = { 0.2f, 0.2f, 0.2f, 1.0f }; glLightModelfv(GL_LIGHT_MODEL_AMBIENT, gl_amb); glEnable(GL_LIGHTING); // Wlaczenie oswietlenia glShadeModel(GL_SMOOTH); // Wybor techniki cieniowania glEnable(GL_LIGHT0); // Wlaczenie 0-go zrodla swiatla glEnable(GL_LIGHT1); Cubes parametri: float m1_amb[] = { 1.0f, 0.0f, 0.0f, 1.0f }; float m1_dif[] = { 1.0f, 0.0f, 0.0f, 1.0f }; float m1_spe[] = { 1.0f, 0.0f, 0.0f, 1.0f }; glMaterialfv(GL_FRONT, GL_AMBIENT, m1_amb); glMaterialfv(GL_FRONT, GL_DIFFUSE, m1_dif); glMaterialfv(GL_FRONT, GL_SPECULAR, m1_spe); glMaterialf(GL_FRONT, GL_SHININESS, 50.0f); Texture parametri: float m1_amb[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float m1_dif[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float m1_spe[] = { 1.0f, 1.0f, 1.0f, 1.0f }; glMaterialfv(GL_FRONT, GL_AMBIENT, m1_amb); glMaterialfv(GL_FRONT, GL_DIFFUSE, m1_dif); glMaterialfv(GL_FRONT, GL_SPECULAR, m1_spe); glMaterialf(GL_FRONT, GL_SHININESS, 0.0f); glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ); Light0: //with some magic sn't working anyway float l0_amb[] = { 0.2f, 0.2f, 0.2f, 1.0f }; float l0_dif[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float l0_spe[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float l0_pos[] = { g_Camera.m_vPosition.x, g_Camera.m_vPosition.y, g_Camera.m_vPosition.z, 1.0f }; float temp = 0.0f, temp2 = 0.0f, temp3 = 0.0f; if(g_Camera.m_vView.z < g_Camera.m_vPosition.z) { temp = g_Camera.m_vView.x - g_Camera.m_vPosition.x; temp2 = g_Camera.m_vView.z - g_Camera.m_vPosition.z; } else { temp = g_Camera.m_vView.x - g_Camera.m_vPosition.x; temp2 = g_Camera.m_vView.z - g_Camera.m_vPosition.z; } float l0_pos1[] = {temp, 0.0f, temp2}; //float l0_pos1[] = {-1.0f, 0.0f, -1.0f}; glLightfv(GL_LIGHT0, GL_AMBIENT, l0_amb); glLightfv(GL_LIGHT0, GL_DIFFUSE, l0_dif); glLightfv(GL_LIGHT0, GL_SPECULAR, l0_spe); glLightfv(GL_LIGHT0, GL_POSITION, l0_pos); glLightf (GL_LIGHT0, GL_SPOT_CUTOFF, 15.0f); glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, l0_pos1); Light1: float l1_amb[] = { 0.2f, 0.2f, 0.2f, 1.0f }; float l1_dif[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float l1_spe[] = { 1.0f, 1.0f, 1.0f, 1.0f }; float l1_pos[] = { 0.0f, 0.0f, 0.0f, 1.0f }; glLightfv(GL_LIGHT1, GL_AMBIENT, l1_amb); glLightfv(GL_LIGHT1, GL_DIFFUSE, l1_dif); glLightfv(GL_LIGHT1, GL_SPECULAR, l1_spe); glLightfv(GL_LIGHT1, GL_POSITION, l1_pos); I know that way I made this very old, but for now i want to keep this like that. I wouldbe realy gratefull if someone can tell me what is wrong with my lights xD full code: link up ^^

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• Tutorials and libraries for OpenGL-ES games on Android

  - by user197141

  What tutorials and libraries are available which can help beginners to develop 2D and 3D games on Android using OpenGL-ES? I'm looking for tutorials which can help me learn OpenGL-ES, and I'm looking for OpenGL-ES libraries which can make life easier for beginners in OpenGL-ES. Since Android is still small, I guess it may be help-full to read iPhone OpenGL-ES tutorials as well, as I suppose the OpenGL-ES functionality is much the same. I have found the following useful information which I would have liked to share: Android tutorials: Basic tutorial covering polygons, no textures anddev forum with some tutorials Other Android OpenGL-ES information: Google IO lecture regarding games, not much OpenGLES The The Khronos Reference Manual is also relevant to have, but its not exactly the best place to start. iPhone OpenGL-ES tutorials (where the OpenGl-ES information is probably useful): http://web.me.com/smaurice/AppleCoder/iPhone_OpenGL/Archive.html http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-table-of.html As for libraries which a beginner might use to get a simpler hands-on experience with OpenGL-ES, I have only found Rokon, which is recently started, thus has many holes and bugs. And it's gnuGPL licensed (at the moment) which means it cannot be used, if we wish to sell our games. What else is out there?

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• Normal maps red in OpenGL?

  - by KaiserJohaan

  I am using Assimp to import 3d models, and FreeImage to parse textures. The problem I am having is that the normal maps are actually red rather than blue when I try to render them as normal diffuse textures. http://i42.tinypic.com/289ing3.png When I open the images in a image-viewing program they do indeed show up as blue. Heres when I create the texture; OpenGLTexture::OpenGLTexture(const std::vector<uint8_t>& textureData, uint32_t textureWidth, uint32_t textureHeight, TextureType textureType, Logger& logger) : mLogger(logger), mTextureID(gNextTextureID++), mTextureType(textureType) { glGenTextures(1, &mTexture); CHECK_GL_ERROR(mLogger); glBindTexture(GL_TEXTURE_2D, mTexture); CHECK_GL_ERROR(mLogger); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, textureWidth, textureHeight, 0, glTextureFormat, GL_UNSIGNED_BYTE, &textureData[0]); CHECK_GL_ERROR(mLogger); glGenerateMipmap(GL_TEXTURE_2D); CHECK_GL_ERROR(mLogger); glBindTexture(GL_TEXTURE_2D, 0); CHECK_GL_ERROR(mLogger); } Here is my fragment shader. You can see I just commented out the normal-map parsing and treated the normal map texture as the diffuse texture to display it and illustrate the problem. As for the rest of the code it interacts as expected with the diffuse textures so I dont see a obvious problem there. "#version 330 \n \ \n \ layout(std140) uniform; \n \ \n \ const int MAX_LIGHTS = 8; \n \ \n \ struct Light \n \ { \n \ vec4 mLightColor; \n \ vec4 mLightPosition; \n \ vec4 mLightDirection; \n \ \n \ int mLightType; \n \ float mLightIntensity; \n \ float mLightRadius; \n \ float mMaxDistance; \n \ }; \n \ \n \ uniform UnifLighting \n \ { \n \ vec4 mGamma; \n \ vec3 mViewDirection; \n \ int mNumLights; \n \ \n \ Light mLights[MAX_LIGHTS]; \n \ } Lighting; \n \ \n \ uniform UnifMaterial \n \ { \n \ vec4 mDiffuseColor; \n \ vec4 mAmbientColor; \n \ vec4 mSpecularColor; \n \ vec4 mEmissiveColor; \n \ \n \ bool mHasDiffuseTexture; \n \ bool mHasNormalTexture; \n \ bool mLightingEnabled; \n \ float mSpecularShininess; \n \ } Material; \n \ \n \ uniform sampler2D unifDiffuseTexture; \n \ uniform sampler2D unifNormalTexture; \n \ \n \ in vec3 frag_position; \n \ in vec3 frag_normal; \n \ in vec2 frag_texcoord; \n \ in vec3 frag_tangent; \n \ in vec3 frag_bitangent; \n \ \n \ out vec4 finalColor; " " \n \ \n \ void CalcGaussianSpecular(in vec3 dirToLight, in vec3 normal, out float gaussianTerm) \n \ { \n \ vec3 viewDirection = normalize(Lighting.mViewDirection); \n \ vec3 halfAngle = normalize(dirToLight + viewDirection); \n \ \n \ float angleNormalHalf = acos(dot(halfAngle, normalize(normal))); \n \ float exponent = angleNormalHalf / Material.mSpecularShininess; \n \ exponent = -(exponent * exponent); \n \ \n \ gaussianTerm = exp(exponent); \n \ } \n \ \n \ vec4 CalculateLighting(in Light light, in vec4 diffuseTexture, in vec3 normal) \n \ { \n \ if (light.mLightType == 1) // point light \n \ { \n \ vec3 positionDiff = light.mLightPosition.xyz - frag_position; \n \ float dist = max(length(positionDiff) - light.mLightRadius, 0); \n \ \n \ float attenuation = 1 / ((dist/light.mLightRadius + 1) * (dist/light.mLightRadius + 1)); \n \ attenuation = max((attenuation - light.mMaxDistance) / (1 - light.mMaxDistance), 0); \n \ \n \ vec3 dirToLight = normalize(positionDiff); \n \ float angleNormal = clamp(dot(normalize(normal), dirToLight), 0, 1); \n \ \n \ float gaussianTerm = 0.0; \n \ if (angleNormal > 0.0) \n \ CalcGaussianSpecular(dirToLight, normal, gaussianTerm); \n \ \n \ return diffuseTexture * (attenuation * angleNormal * Material.mDiffuseColor * light.mLightIntensity * light.mLightColor) + \n \ (attenuation * gaussianTerm * Material.mSpecularColor * light.mLightIntensity * light.mLightColor); \n \ } \n \ else if (light.mLightType == 2) // directional light \n \ { \n \ vec3 dirToLight = normalize(light.mLightDirection.xyz); \n \ float angleNormal = clamp(dot(normalize(normal), dirToLight), 0, 1); \n \ \n \ float gaussianTerm = 0.0; \n \ if (angleNormal > 0.0) \n \ CalcGaussianSpecular(dirToLight, normal, gaussianTerm); \n \ \n \ return diffuseTexture * (angleNormal * Material.mDiffuseColor * light.mLightIntensity * light.mLightColor) + \n \ (gaussianTerm * Material.mSpecularColor * light.mLightIntensity * light.mLightColor); \n \ } \n \ else if (light.mLightType == 4) // ambient light \n \ return diffuseTexture * Material.mAmbientColor * light.mLightIntensity * light.mLightColor; \n \ else \n \ return vec4(0.0); \n \ } \n \ \n \ void main() \n \ { \n \ vec4 diffuseTexture = vec4(1.0); \n \ if (Material.mHasDiffuseTexture) \n \ diffuseTexture = texture(unifDiffuseTexture, frag_texcoord); \n \ \n \ vec3 normal = frag_normal; \n \ if (Material.mHasNormalTexture) \n \ { \n \ diffuseTexture = vec4(normalize(texture(unifNormalTexture, frag_texcoord).xyz * 2.0 - 1.0), 1.0); \n \ // vec3 normalTangentSpace = normalize(texture(unifNormalTexture, frag_texcoord).xyz * 2.0 - 1.0); \n \ //mat3 tangentToWorldSpace = mat3(normalize(frag_tangent), normalize(frag_bitangent), normalize(frag_normal)); \n \ \n \ // normal = tangentToWorldSpace * normalTangentSpace; \n \ } \n \ \n \ if (Material.mLightingEnabled) \n \ { \n \ vec4 accumLighting = vec4(0.0); \n \ \n \ for (int lightIndex = 0; lightIndex < Lighting.mNumLights; lightIndex++) \n \ accumLighting += Material.mEmissiveColor * diffuseTexture + \n \ CalculateLighting(Lighting.mLights[lightIndex], diffuseTexture, normal); \n \ \n \ finalColor = pow(accumLighting, Lighting.mGamma); \n \ } \n \ else { \n \ finalColor = pow(diffuseTexture, Lighting.mGamma); \n \ } \n \ } \n"; Why is this? does normal-map textures need some sort of special treatment in opengl?

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• Nothing drawing on screen OpenGL with GLSL

  - by codemonkey

  I hate to be asking this kind of question here, but I am at a complete loss as to what is going wrong, so please bear with me. I am trying to render a single cube (voxel) in the center of the screen, through OpenGL with GLSL on Mac I begin by setting up everything using glut glutInit(&argc, argv); glutInitDisplayMode(GLUT_RGBA|GLUT_ALPHA|GLUT_DOUBLE|GLUT_DEPTH); glutInitWindowSize(DEFAULT_WINDOW_WIDTH, DEFAULT_WINDOW_HEIGHT); glutCreateWindow("Cubez-OSX"); glutReshapeFunc(reshape); glutDisplayFunc(render); glutIdleFunc(idle); _electricSheepEngine=new ElectricSheepEngine(DEFAULT_WINDOW_WIDTH, DEFAULT_WINDOW_HEIGHT); _electricSheepEngine->initWorld(); glutMainLoop(); Then inside the engine init camera & projection matrices: cameraPosition=glm::vec3(2,2,2); cameraTarget=glm::vec3(0,0,0); cameraUp=glm::vec3(0,0,1); glm::vec3 cameraDirection=glm::normalize(cameraPosition-cameraTarget); cameraRight=glm::cross(cameraDirection, cameraUp); cameraRight.z=0; view=glm::lookAt(cameraPosition, cameraTarget, cameraUp); lensAngle=45.0f; aspectRatio=1.0*(windowWidth/windowHeight); nearClippingPlane=0.1f; farClippingPlane=100.0f; projection=glm::perspective(lensAngle, aspectRatio, nearClippingPlane, farClippingPlane); then init shaders and check compilation and bound attributes & uniforms to be correctly bound (my previous question) These are my two shaders, vertex: #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); } and fragment: #version 120 varying vec3 fragColor; void main(void) { gl_FragColor = vec4(fragColor,1.0); } init the cube: setPosition(glm::vec3(0,0,0)); struct voxelData data[]={ //front face {{-1.0, -1.0, 1.0}, {0.0, 0.0, 1.0}}, {{ 1.0, -1.0, 1.0}, {0.0, 1.0, 1.0}}, {{ 1.0, 1.0, 1.0}, {0.0, 0.0, 1.0}}, {{-1.0, 1.0, 1.0}, {0.0, 1.0, 1.0}}, //back face {{-1.0, -1.0, -1.0}, {0.0, 0.0, 1.0}}, {{ 1.0, -1.0, -1.0}, {0.0, 1.0, 1.0}}, {{ 1.0, 1.0, -1.0}, {0.0, 0.0, 1.0}}, {{-1.0, 1.0, -1.0}, {0.0, 1.0, 1.0}} }; glGenBuffers(1, &modelVerticesBufferObject); glBindBuffer(GL_ARRAY_BUFFER, modelVerticesBufferObject); glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, 0); const GLubyte indices[] = { // Front 0, 1, 2, 2, 3, 0, // Back 4, 6, 5, 4, 7, 6, // Left 2, 7, 3, 7, 6, 2, // Right 0, 4, 1, 4, 1, 5, // Top 6, 2, 1, 1, 6, 5, // Bottom 0, 3, 7, 0, 7, 4 }; glGenBuffers(1, &modelFacesBufferObject); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, modelFacesBufferObject); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); and then the render call: glClearColor(0.52, 0.8, 0.97, 1.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnable(GL_DEPTH_TEST); //use the shader glUseProgram(shaderProgram); //enable attributes in program glEnableVertexAttribArray(shaderAttribute_position); glEnableVertexAttribArray(shaderAttribute_color); //model matrix using model position vector glm::mat4 mvp=projection*view*voxel->getModelMatrix(); glUniformMatrix4fv(shaderAttribute_mvp, 1, GL_FALSE, glm::value_ptr(mvp)); glBindBuffer(GL_ARRAY_BUFFER, voxel->modelVerticesBufferObject); glVertexAttribPointer(shaderAttribute_position, // attribute 3, // number of elements per vertex, here (x,y) GL_FLOAT, // the type of each element GL_FALSE, // take our values as-is sizeof(struct voxelData), // coord every (sizeof) elements 0 // offset of first element ); glBindBuffer(GL_ARRAY_BUFFER, voxel->modelVerticesBufferObject); glVertexAttribPointer(shaderAttribute_color, // attribute 3, // number of colour elements per vertex, here (x,y) GL_FLOAT, // the type of each element GL_FALSE, // take our values as-is sizeof(struct voxelData), // coord every (sizeof) elements (GLvoid *)(offsetof(struct voxelData, color3D)) // offset of colour data ); //draw the model by going through its elements array glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, voxel->modelFacesBufferObject); int bufferSize; glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &bufferSize); glDrawElements(GL_TRIANGLES, bufferSize/sizeof(GLushort), GL_UNSIGNED_SHORT, 0); //close up the attribute in program, no more need glDisableVertexAttribArray(shaderAttribute_position); glDisableVertexAttribArray(shaderAttribute_color); but on screen all I get is the clear color :$ I generate my model matrix using: modelMatrix=glm::translate(glm::mat4(1.0), position); which in debug turns out to be for the position of (0,0,0): |1, 0, 0, 0| |0, 1, 0, 0| |0, 0, 1, 0| |0, 0, 0, 1| Sorry for such a question, I know it is annoying to look at someone's code, but I promise I have tried to debug around and figure it out as much as I can, and can't come to a solution Help a noob please? EDIT: Full source here, if anyone wants

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• Good resources for learning modern OpenGL (3.0 or later)?

  - by MatterGoal

  I stumble upon the search of a good resource to start with OpenGL (3.0 or later) . Well, I found a lot of books but none of them can be considered a good resource! Here two examples: OpenGL Programming Guide (7th edition) http://www.amazon.com/exec/obidos/ASIN/0321552628/khongrou-20 This is FULL of deprecated material! Almost every chapters begin with a note about that. OpenGL Superbible (5th Edition) http://www.amazon.com/exec/obidos/ASIN/0321712617/khongrou-20 This book uses a library created by the author to explain the main arguments, hiding what you want to learn! I don't want to learn how to use your library! I want to learn OpenGL! I hope that you understand this is not the same question like "hey I'm not able to use Google... tell me how to learn OpenGL". I've just finished a full and deep search but I can't find a good and complete resource to learn the "new" OpenGL avoiding deprecated topics. Can someone heading me in the right direction? I know C++ and I have 10 years of experience in development... where I can find a good resource?! I want to spend time on it and I want to learn deeply. (please feel free to edit my question, my English is terrible!)

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• OpenGL support no longer available

  - by Aznfin

  I've been using OpenGL hardware acceleration in programs such as Adobe Photoshop CS4 and Adobe After Effects CS4. I've noticed that recently the options for OpenGL previews are disabled because my graphics card seems to not support OpenGL. But that doesn't make any sense whatsoever. I know for a fact that my graphics card does have support for OpenGL and it worked before. I checked for driver updates just the other day. Anybody know what's going on? Info: Operating System: Windows 7 Home Premium 64-bit GPU: ATI Radeon HD 3200 Driver Packaging Version: 8.69-091211a-094296C-ATI Catalyst™ Version: 09.12 Provider: ATI Technologies Inc. 2D Driver Version: 8.01.01.994 2D Driver File Path: /REGISTRY/MACHINE/SYSTEM/ControlSet001/Control/CLASS /{4D36E968-E325-11CE-BFC1-08002BE10318}/0000 Direct3D Version: 8.14.10.0723 OpenGL Version: 6.14.10.9252 Catalyst™ Control Center Version: 2009.1211.1547.28237

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• OpenGL ES 1.1 vs 2.0 for 2D Graphics, with rotated sprites?

  - by Lee Olayvar

  I am having trouble finding information related to which i should choose, OpenGL ES 1.1 or 2.0 for 2D graphics. OpenGL ES 1.1 on Android is a bit limited to my knowledge, and based purely on sprite count the only useful renderer is draw_texture() (as far as i know). However, that does not have rotation and rotation is very important to me. Now with the NDK adding support for OpenGL ES 2.0, i am trying to figure out if there is anything that preforms as well as draw_texture(), but can handle rotation. Anyone have any information on if 2.0 can help me in this area?

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• Tutoriel OpenGL Moderne : les extensions OpenGL, comprenez comment fonctionne l'ajout de fonctionnalités dans OpenGL 3 et supérieur

  Bonjour à tous,La rubrique 2D/3D/Jeux est heureuse de vous présenter une la suite de la série de tutoriels consacrée à OpenGL moderne (les versions à partir d'OpenGL 3.3). Ces tutoriels vous permettront d'intégrer facilement les nouveaux concepts d'OpenGL afin de profiter au maximum des dernières technologies de vos cartes graphiques. Ce douzième tutoriel vous informera sur ce que sont les extensions dans OpenGL et comment elles fonctionnent.Bonne lecture.

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• Opengl glVertexAttrib4fv doesn't work?

  - by Naor

  This is my vertex shader: static const GLchar * vertex_shader_source[] = { "#version 430 core \n" "layout (location = 0) in vec4 offset; \n" "void main(void) \n" "{ \n" " const vec4 vertices[3] = vec4[3](vec4( 0.25, -0.25, 0.5, 1.0),\n" " vec4(-0.25, -0.25, 0.5, 1.0), \n" " vec4( 0.25, 0.25, 0.5, 1.0)); \n" " gl_Position = vertices[gl_VertexID] + offset; \n" "} \n" }; and this is what im trying to do: glUseProgram(rendering_program); GLfloat attrib[] = { (float)sin(currentTime) * 0.5f, (float)cos(currentTime) * 0.6f, 0.0f, 0.0f }; glVertexAttrib4fv(0, attrib); glDrawArrays(GL_TRIANGLES, 0, 3); currentTime - The number in seconds since the program has started. Expected result - Triangle moving around the window. Its from the SuperBible book (sixth edition), this is the full code:http://pastebin.com/xA3eCKz1 The triangle should move across the screen but it doesn't.

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• OpenGL 2 on Android: native window

  - by ThreaderSlash

  According to OGLES specification, we have the following definition: EGLSurface eglCreateWindowSurface(EGLDisplay display, EGLConfig config, NativeWindowType native_window, EGLint const * attrib_list) More details, here: http://www.khronos.org/opengles/documentation/opengles1_0/html/eglCreateWindowSurface.html And also by definition: int32_t ANativeWindow_setBuffersGeometry(ANativeWindow* window, int32_t width, int32_t height, int32_t format); More details, here: http://mobilepearls.com/labs/native-android-api I am running Android Native App on OGLES 2 and debugging it in a Samsung Nexus device. For setting up the 3D scene graph environment, the following variables are defined: struct android_app { ... ANativeWindow* window; }; android_app* mApplication; ... mApplication=&pApplication; And to initialize the App, we run the commands in the code: ANativeWindow_setBuffersGeometry(mApplication->window, 0, 0, lFormat); mSurface = eglCreateWindowSurface(mDisplay, lConfig, mApplication->window, NULL); Funny to say is that, the command ANativeWindow_setBuffersGeometry behaves as expected and works fine according to its definition, accepting all the parameters sent to it. But the eglCreateWindowSurface does no accept the parameter mApplication-window, as it should accept according to its definition. Instead, it looks for the following input: EGLNativeWindowType hWnd; mSurface = eglCreateWindowSurface(mDisplay,lConfig,hWnd,NULL); As an alternative, I considered to use instead: NativeWindowType hWnd=android_createDisplaySurface(); But debugger says: Function 'android_createDisplaySurface' could not be resolved Can someone tell if there is a way to convert mApplication-window? In a way that the data from the android_app get accepted to the window surface?

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• Android OpenGL ES 2 framebuffer not working properly

  - by user16547

  I'm trying to understand how framebuffers work. In order to achieve that, I want to draw a very basic triangle to a framebuffer texture and then draw the resulting texture to a quad on the default framebuffer. However, I only get a fraction of the triangle like below. LE: The triangle's coordinates should be (1) -0.5f, -0.5f, 0 (2) 0.5f, -0.5f, 0 (3) 0, 0.5f, 0 Here's the code to render: @Override public void onDrawFrame(GL10 gl) { renderNormalStuff(); renderFramebufferTexture(); } protected void renderNormalStuff() { GLES20.glViewport(0, 0, texWidth, texHeight); GLUtils.updateProjectionMatrix(mProjectionMatrix, texWidth, texHeight); GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fbo[0]); GLES20.glUseProgram(mProgram); GLES20.glClearColor(.5f, .5f, .5f, 1); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT); Matrix.setIdentityM(mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); GLES20.glUniformMatrix4fv(u_MVPMatrix, 1, false, mMVPMatrix, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo[0]); GLES20.glVertexAttribPointer(a_Position, 3, GLES20.GL_FLOAT, false, 12, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbo[1]); GLES20.glVertexAttribPointer(a_Color, 4, GLES20.GL_FLOAT, false, 16, 0); GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, ibo[0]); GLES20.glDrawElements(GLES20.GL_TRIANGLES, indexBuffer.capacity(), GLES20.GL_UNSIGNED_BYTE, 0); GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0); GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0); GLES20.glUseProgram(0); } private void renderFramebufferTexture() { GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0); GLES20.glUseProgram(fboProgram); GLES20.glClearColor(.0f, .5f, .25f, 1); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); GLES20.glViewport(0, 0, width, height); GLUtils.updateProjectionMatrix(mProjectionMatrix, width, height); Matrix.setIdentityM(mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); GLES20.glUniformMatrix4fv(fbo_u_MVPMatrix, 1, false, mMVPMatrix, 0); //draw the texture GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture[0]); GLES20.glUniform1i(fbo_u_Texture, 0); GLUtils.sendBufferData(fbo_a_Position, 3, quadPositionBuffer); GLUtils.sendBufferData(fbo_a_TexCoordinate, 2, quadTexCoordinate); GLES20.glDrawElements(GLES20.GL_TRIANGLES, quadIndexBuffer.capacity(), GLES20.GL_UNSIGNED_BYTE, quadIndexBuffer); GLES20.glUseProgram(0); }

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• Get vertex colors from fbx (OpenGL, FBX SDK)

  - by instancedName

  I'm kinda stuck with this one. I managed to get vertex positions, indices, normals, but I don't quite understand how te get vertex colors. I need them to fill my buffer. I tried funcion mesh-GetElementVertexColorCount() and then to iterate trough all of them, but it returns zero. I alse tried to get layer, and then use layer-GetVertexColors(), but it returns NULL pointer. Can anyone help me with this one?

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• OpenGL ES Shader help (Blending)

  - by Chris

  Earlier I required assistance getting to grips with how to retain the alpha channel of a transparent texture in my colourised texture shader program. Whilst playing with that first version of my program (before obtaining the solution to my first requirement), I managed to enable transparency for the whole texture (effectively blending via GLSL), and I quite liked this, and I would now like to know if and how it is possible to retain this blending effect, on top of the existing output without affecting the original alpha channel - as I don't know how to input this transparency via the parameter that is already being provided with the textures alpha channel. A basic example of the blending program I am referring to (minus any other functionality) is as follows... varying vec2 texCoord; uniform sampler2D texSampler; void main() { gl_FragColor = vec4(texture2D(texSampler,texCoord).xyz,0.5); } Where 0.5 is the transparency (blending effect) of the whole texture. This is the current version of my program, which provides the ability to colour a texture according the colour parameter passed to the program, and retains the alpha channel of the original texture. varying vec2 texCoord; uniform sampler2D texSampler; uniform vec3 colour; void main() { gl_FragColor = vec4(colour,1) * vec4(texture2D(texSampler,texCoord).xyz,texture2D(texSampler,texCoord).w); } I need to know if it is possible to apply transparency on top this program, without affecting the original alpha channel which I have already preserved. I hope this makes enough sense, I am sure it is possible, and if so I should imagine it is rather simple, but this has me stumped. Any help much appreachiated. Cheers, Chris

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• OpenGL ES 2 shaders for drawing buildings and roads like Google Maps does

  - by Pris

  I'm trying to create a shader that'll give me an effect similar to what buildings and roads look like on 3D Google Maps. You can see the effect interactively if you enable WebGL at maps.google.com, and I also found a couple of screenshots that illustrate what I'm trying to achieve: Thing I noticed: There's some kind of transparency thing going on with the roads/ground and the buildings, but not between the buildings themselves. It might be that they're rendering the ground and roads after the buildings with the right blend functions to achieve that effect. If you look closely, you'll see parts of the building profiles have an outline. The roads also have nice clean outlines. There are a lot of techniques for outlining things with shaders... but I'm curious to find out what might have been used in this case considering mobile hardware and a large number of entities with outlines (roads and buildings) I'm assuming that for the lighting, some sort of simple diffuse per-vertex shader is being used for the buildings though I could be wrong. I'm especially curious about the 'look' they achieved with buildings (clean, precise outlines/shading). It reminds me a little of what you'd see when designing stuff with CAD applications like SolidWorks: I'd appreciate any advice on achieving this kind of look with ES 2 shaders.

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• Interpolating height on opengl quad

  - by ThePlague

  Okay I've got a quad, see picture. And want to find the height at any point in the quad, is there a way to do this accurately as bilinear interpolation doesn't work in this case. As you can see the trees trunk is well beneath the terrain and should be at the same height as the trunks around it. I know the altitude of the vertices marked by a red circle and the centre red circle is roughly where the base should be, I've also crudely added a line as that surface is not flat.

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• View matrix in opengl

  - by user5584

  Hi! Sorry for my clumsy question. But I don't know where I am wrong at creating view matrix. I have the following code: createMatrix(vec4f(xAxis.x, xAxis.y, xAxis.z, dot(xAxis,eye)), vec4f( yAxis.x_, yAxis.y_, yAxis.z_, dot(yAxis,eye)), vec4f(-zAxis.x_, -zAxis.y_, -zAxis.z_, -dot(zAxis,eye)), vec4f(0, 0, 0, 1)); //column1, column2,... I have tried to transpose it, but with no success. I have also tried to use gluLookAt(...) with success. At the reference page, I watched the remarks about the to-be-created matrix, and it seems the same as mine. Where I am wrong?

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• OpenGL - Cascaded shadow mapping - Texture lookup

  - by Silverlan

  I'm trying to implement cascaded shadow mapping in my engine, but I'm somewhat stuck at the last step. For testing purposes I've made sure all cascades encompass my entire scene. The result is currently this: The different intensity of the cascades is not on purpose, it's actually the problem. This is how I do the texture lookup for the shadow maps inside the fragment shader: layout(std140) uniform CSM { vec4 csmFard; // far distances for each cascade mat4 csmVP[4]; // View-Projection Matrix int numCascades; // Number of cascades to use. In this example it's 4. }; uniform sampler2DArrayShadow csmTextureArray; // The 4 shadow maps in vec4 csmPos[4]; // Vertex position in shadow MVP space float GetShadowCoefficient() { int index = numCascades -1; vec4 shadowCoord; for(int i=0;i<numCascades;i++) { if(gl_FragCoord.z < csmFard[i]) { shadowCoord = csmPos[i]; index = i; break; } } shadowCoord.w = shadowCoord.z; shadowCoord.z = float(index); shadowCoord.x = shadowCoord.x *0.5f +0.5f; shadowCoord.y = shadowCoord.y *0.5f +0.5f; return shadow2DArray(csmTextureArray,shadowCoord).x; } I then use the return value and simply multiply it with the diffuse color. That explains the different intensity of the cascades, since I'm grabbing the depth value directly from the texture. I've tried to do a depth comparison instead, but with limited success: [...] // Same code as above shadowCoord.w = shadowCoord.z; shadowCoord.z = float(index); shadowCoord.x = shadowCoord.x *0.5f +0.5f; shadowCoord.y = shadowCoord.y *0.5f +0.5f; float z = shadow2DArray(csmTextureArray,shadowCoord).x; if(z < shadowCoord.w) return 0.25f; return 1.f; } While this does give me the same shadow value everywhere, it only works for the first cascade, all others are blank: (I colored the cascades because otherwise the transitions wouldn't be visible in this case) What am I missing here?

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• OpenGL 2D Depth Perception

  - by Stephen James

  This is the first time i have ever commented on a forum about programming, so sorry if I'm not specific enough. Here's my problem: I have a 2D RPG game written in Java using LWJGL. All works fine, but at the moment I'm having trouble deciding what the best way to do depth perception is. So , for example, if the player goes in front of the tree/enemy (lower than the objects y-coordinate) then show the player in front), if the player goes behind the tree/enemy (higher than the objects specific y-coordinate), then show the player behind the object. I have tried writing a block of code to deal with this, and it works quite well for the trees, but not for the enemies yet. Is there a simpler way of doing this in LWJGL that I'm missing? Thanks :)

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• OpenGL 2D Depth Perception

  - by Stephen James

  I have a 2D RPG game written in Java using LWJGL. All works fine, but at the moment I'm having trouble deciding what the best way to do depth perception is. So , for example, if the player goes in front of the tree/enemy (lower than the objects y-coordinate) then show the player in front), if the player goes behind the tree/enemy (higher than the objects specific y-coordinate), then show the player behind the object. I have tried writing a block of code to deal with this, and it works quite well for the trees, but not for the enemies yet. Is there a simpler way of doing this in LWJGL that I'm missing?

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• Setting up cube map texture parameters in OpenGL

  - by KaiserJohaan

  I see alot of tutorials and sources use the following code snippet when defining each face of a cube map: for (i = 0; i < 6; i++) glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, InternalFormat, size, size, 0, Format, Type, NULL); Is it safe to assume GL_TEXTURE_CUBE_MAP_POSITIVE_X + i will properly iterate the following cube map targets, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y etc?

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• Taking fixed direction on hemisphere and project to normal (openGL)

  - by Maik Xhani

  I am trying to perform sampling using hemisphere around a surface normal. I want to experiment with fixed directions (and maybe jitter slightly between frames). So I have those directions: vec3 sampleDirections[6] = {vec3(0.0f, 1.0f, 0.0f), vec3(0.0f, 0.5f, 0.866025f), vec3(0.823639f, 0.5f, 0.267617f), vec3(0.509037f, 0.5f, -0.700629f), vec3(-0.509037f, 0.5f, -0.700629), vec3(-0.823639f, 0.5f, 0.267617f)}; now I want the first direction to be projected on the normal and the others accordingly. I tried these 2 codes, both failing. This is what I used for random sampling (it doesn't seem to work well, the samples seem to be biased towards a certain direction) and I just used one of the fixed directions instead of s (here is the code of the random sample, when i used it with the fixed direction i didn't use theta and phi). vec3 CosWeightedRandomHemisphereDirection( vec3 n, float rand1, float rand2 ) float theta = acos(sqrt(1.0f-rand1)); float phi = 6.283185f * rand2; vec3 s = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta)); vec3 v = normalize(cross(n,vec3(0.0072, 1.0, 0.0034))); vec3 u = cross(v, n); u = s.x*u; v = s.y*v; vec3 w = s.z*n; vec3 direction = u+v+w; return normalize(direction); } ** EDIT ** This is the new code vec3 FixedHemisphereDirection( vec3 n, vec3 sampleDir) { vec3 x; vec3 z; if(abs(n.x) < abs(n.y)){ if(abs(n.x) < abs(n.z)){ x = vec3(1.0f,0.0f,0.0f); }else{ x = vec3(0.0f,0.0f,1.0f); } }else{ if(abs(n.y) < abs(n.z)){ x = vec3(0.0f,1.0f,0.0f); }else{ x = vec3(0.0f,0.0f,1.0f); } } z = normalize(cross(x,n)); x = cross(n,z); mat3 M = mat3( x.x, n.x, z.x, x.y, n.y, z.y, x.z, n.z, z.z); return M*sampleDir; } So if my n = (0,0,1); and my sampleDir = (0,1,0); shouldn't the M*sampleDir be (0,0,1)? Cause that is what I was expecting.

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• OpenGL 2.1+ Render with data returned form assimp library

  - by Bình Nguyên

  I have just readed this tutorial about load a 3D model file: http://www.lighthouse3d.com/cg-topics/code-samples/importing-3d-models-with-assimp/#comment-14551. Its render routine uses a recursive_render function to scan all node. My question: What is a aiNode struct store? What different form this method and above method: for (int i=0; imNumMesh; ++i) { draw scene-mMeshes[i]; } Thanks for reading!

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