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  • New to CG shader programming, what program should I use to write and test them?

    - by Notbad
    I have started witting some shaders. First ones were fairly easy to write in notepad but now I need something with a bit more meat. I have checked rendermonnkey that seems to support CG but it is really old and don't know if it is a good option. On the other hand there exist this FX Composer 2.0 but it seems somthing that could really distract me from learning shaders because it seems a pretty deep program. Are there any other possibilities? There's a really nice alternative to write shaders named ShaderToy but just supports GLSL. Any information will be really welcomed. Thanks in advance.

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  • Geometry instancing in OpenGL ES 2.0

    - by seahorse
    I am planning to do geometry instancing in OpenGL ES 2.0 Basically I plan to render the same geometry(a chair) maybe 1000 times in my scene. What is the best way to do this in OpenGL ES 2.0? I am considering passing model view mat4 as an attribute. Since attributes are per vertex data do I need to pass this same mat4, three times for each vertex of the same triangle(since modelview remains constant across vertices of the triangle). That would amount to a lot of extra data sent to the GPU( 2 extra vertices*16 floats*(Number of triangles) amount of extra data). Or should I be sending the mat4 only once per triangle?But how is that possible using attributes since attributes are defined as "per vertex" data? What is the best and efficient way to do instancing in OpenGL ES 2.0?

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  • Outline Shader Effect for Orthogonal Geometry in XNA

    - by Griffin
    I just recently started learning the art of shading, but I can't give an outline width to 2D, concave geometry when restrained to a single vertex/pixel shader technique (thanks to XNA). the shape I need to give an outline to has smooth, per-vertex coloring, as well as opacity. The outline, which has smooth, per-vertex coloring, variable width, and opacity cannot interfere with the original shape's colors. A pixel depth border detection algorithm won't work because pixel depth isn't a 3.0 semantic. expanding geometry / redrawing won't work because it interferes with the original shape's colors. I'm wondering if I can do something with the stencil/depth buffer outside of the shader functions since I have access to that through the graphics device. But I don't believe I'm able to manipulate actual values. How might I do this?

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  • Render To Texture Using OpenGL is not working but normal rendering works just fine

    - by Franky Rivera
    things I initialize at the beginning of the program I realize not all of these pertain to my issue I just copy and pasted what I had //overall initialized //things openGL related I initialize earlier on in the project glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClearDepth( 1.0f ); glEnable(GL_ALPHA_TEST); glEnable( GL_STENCIL_TEST ); glEnable(GL_DEPTH_TEST); glDepthFunc( GL_LEQUAL ); glEnable(GL_CULL_FACE); glFrontFace( GL_CCW ); glEnable(GL_COLOR_MATERIAL); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST ); //we also initialize our shader programs //(i added some shader program functions for definitions) //this enum list is else where in code //i figured it would help show you guys more about my //shader compile creation function right under this enum list VVVVVV /*enum eSHADER_ATTRIB_LOCATION { VERTEX_ATTRIB = 0, NORMAL_ATTRIB = 2, COLOR_ATTRIB, COLOR2_ATTRIB, FOG_COORD, TEXTURE_COORD_ATTRIB0 = 8, TEXTURE_COORD_ATTRIB1, TEXTURE_COORD_ATTRIB2, TEXTURE_COORD_ATTRIB3, TEXTURE_COORD_ATTRIB4, TEXTURE_COORD_ATTRIB5, TEXTURE_COORD_ATTRIB6, TEXTURE_COORD_ATTRIB7 }; */ //if we fail making our shader leave if( !testShader.CreateShader( "SimpleShader.vp", "SimpleShader.fp", 3, VERTEX_ATTRIB, "vVertexPos", NORMAL_ATTRIB, "vNormal", TEXTURE_COORD_ATTRIB0, "vTexCoord" ) ) return false; if( !testScreenShader.CreateShader( "ScreenShader.vp", "ScreenShader.fp", 3, VERTEX_ATTRIB, "vVertexPos", NORMAL_ATTRIB, "vNormal", TEXTURE_COORD_ATTRIB0, "vTexCoord" ) ) return false; SHADER PROGRAM FUNCTIONS bool CShaderProgram::CreateShader( const char* szVertexShaderName, const char* szFragmentShaderName, ... ) { //here are our handles for the openGL shaders int iGLVertexShaderHandle = -1, iGLFragmentShaderHandle = -1; //get our shader data char *vData = 0, *fData = 0; int vLength = 0, fLength = 0; LoadShaderFile( szVertexShaderName, &vData, &vLength ); LoadShaderFile( szFragmentShaderName, &fData, &fLength ); //data if( !vData ) return false; //data if( !fData ) { delete[] vData; return false; } //create both our shader objects iGLVertexShaderHandle = glCreateShader( GL_VERTEX_SHADER ); iGLFragmentShaderHandle = glCreateShader( GL_FRAGMENT_SHADER ); //well we got this far so we have dynamic data to clean up //load vertex shader glShaderSource( iGLVertexShaderHandle, 1, (const char**)(&vData), &vLength ); //load fragment shader glShaderSource( iGLFragmentShaderHandle, 1, (const char**)(&fData), &fLength ); //we are done with our data delete it delete[] vData; delete[] fData; //compile them both glCompileShader( iGLVertexShaderHandle ); //get shader status int iShaderOk; glGetShaderiv( iGLVertexShaderHandle, GL_COMPILE_STATUS, &iShaderOk ); if( iShaderOk == GL_FALSE ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLVertexShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLVertexShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szVertexShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLVertexShaderHandle); return false; } glCompileShader( iGLFragmentShaderHandle ); //get shader status glGetShaderiv( iGLFragmentShaderHandle, GL_COMPILE_STATUS, &iShaderOk ); if( iShaderOk == GL_FALSE ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLFragmentShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLFragmentShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szFragmentShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLFragmentShaderHandle); return false; } //lets check to see if the fragment shader compiled int iCompiled = 0; glGetShaderiv( iGLVertexShaderHandle, GL_COMPILE_STATUS, &iCompiled ); if( !iCompiled ) { //this shader did not compile leave return false; } //lets check to see if the fragment shader compiled glGetShaderiv( iGLFragmentShaderHandle, GL_COMPILE_STATUS, &iCompiled ); if( !iCompiled ) { char* buffer; //get what happend with our shader glGetShaderiv( iGLFragmentShaderHandle, GL_INFO_LOG_LENGTH, &iShaderOk ); buffer = new char[iShaderOk]; glGetShaderInfoLog( iGLFragmentShaderHandle, iShaderOk, NULL, buffer ); //sprintf_s( buffer, "Failure Our Object For %s was not created", szFileName ); MessageBoxA( NULL, buffer, szFragmentShaderName, MB_OK ); //delete our dynamic data free( buffer ); glDeleteShader(iGLFragmentShaderHandle); return false; } //make our new shader program m_iShaderProgramHandle = glCreateProgram(); glAttachShader( m_iShaderProgramHandle, iGLVertexShaderHandle ); glAttachShader( m_iShaderProgramHandle, iGLFragmentShaderHandle ); glLinkProgram( m_iShaderProgramHandle ); int iLinked = 0; glGetProgramiv( m_iShaderProgramHandle, GL_LINK_STATUS, &iLinked ); if( !iLinked ) { //we didn't link return false; } //NOW LETS CREATE ALL OUR HANDLES TO OUR PROPER LIKING //start from this parameter va_list parseList; va_start( parseList, szFragmentShaderName ); //read in number of variables if any unsigned uiNum = 0; uiNum = va_arg( parseList, unsigned ); //for loop through our attribute pairs int enumType = 0; for( unsigned x = 0; x < uiNum; ++x ) { //specify our attribute locations enumType = va_arg( parseList, int ); char* name = va_arg( parseList, char* ); glBindAttribLocation( m_iShaderProgramHandle, enumType, name ); } //end our list parsing va_end( parseList ); //relink specify //we have custom specified our attribute locations glLinkProgram( m_iShaderProgramHandle ); //fill our handles InitializeHandles( ); //everything went great return true; } void CShaderProgram::InitializeHandles( void ) { m_uihMVP = glGetUniformLocation( m_iShaderProgramHandle, "mMVP" ); m_uihWorld = glGetUniformLocation( m_iShaderProgramHandle, "mWorld" ); m_uihView = glGetUniformLocation( m_iShaderProgramHandle, "mView" ); m_uihProjection = glGetUniformLocation( m_iShaderProgramHandle, "mProjection" ); ///////////////////////////////////////////////////////////////////////////////// //texture handles m_uihDiffuseMap = glGetUniformLocation( m_iShaderProgramHandle, "diffuseMap" ); if( m_uihDiffuseMap != -1 ) { //store what texture index this handle will be in the shader glUniform1i( m_uihDiffuseMap, RM_DIFFUSE+GL_TEXTURE0 ); (0)+ } m_uihNormalMap = glGetUniformLocation( m_iShaderProgramHandle, "normalMap" ); if( m_uihNormalMap != -1 ) { //store what texture index this handle will be in the shader glUniform1i( m_uihNormalMap, RM_NORMAL+GL_TEXTURE0 ); (1)+ } } void CShaderProgram::SetDiffuseMap( const unsigned& uihDiffuseMap ) { (0)+ glActiveTexture( RM_DIFFUSE+GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D, uihDiffuseMap ); } void CShaderProgram::SetNormalMap( const unsigned& uihNormalMap ) { (1)+ glActiveTexture( RM_NORMAL+GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D, uihNormalMap ); } //MY 2 TEST SHADERS also my math order is correct it pertains to my matrix ordering in my math library once again i've tested the basic rendering. rendering to the screen works fine ----------------------------------------SIMPLE SHADER------------------------------------- //vertex shader looks like this #version 330 in vec3 vVertexPos; in vec3 vNormal; in vec2 vTexCoord; uniform mat4 mWorld; // Model Matrix uniform mat4 mView; // Camera View Matrix uniform mat4 mProjection;// Camera Projection Matrix out vec2 vTexCoordVary; // Texture coord to the fragment program out vec3 vNormalColor; void main( void ) { //pass the texture coordinate vTexCoordVary = vTexCoord; vNormalColor = vNormal; //calculate our model view projection matrix mat4 mMVP = (( mWorld * mView ) * mProjection ); //result our position gl_Position = vec4( vVertexPos, 1 ) * mMVP; } //fragment shader looks like this #version 330 in vec2 vTexCoordVary; in vec3 vNormalColor; uniform sampler2D diffuseMap; uniform sampler2D normalMap; out vec4 fragColor[2]; void main( void ) { //CORRECT fragColor[0] = texture( normalMap, vTexCoordVary ); fragColor[1] = vec4( vNormalColor, 1.0 ); }; ----------------------------------------SCREEN SHADER------------------------------------- //vertext shader looks like this #version 330 in vec3 vVertexPos; // This is the position of the vertex coming in in vec2 vTexCoord; // This is the texture coordinate.... out vec2 vTexCoordVary; // Texture coord to the fragment program void main( void ) { vTexCoordVary = vTexCoord; //set our position gl_Position = vec4( vVertexPos.xyz, 1.0f ); } //fragment shader looks like this #version 330 in vec2 vTexCoordVary; // Incoming "varying" texture coordinate uniform sampler2D diffuseMap;//the tile detail texture uniform sampler2D normalMap; //the normal map from earlier out vec4 vTheColorOfThePixel; void main( void ) { //CORRECT vTheColorOfThePixel = texture( normalMap, vTexCoordVary ); }; .Class RenderTarget Main Functions //here is my render targets create function bool CRenderTarget::Create( const unsigned uiNumTextures, unsigned uiWidth, unsigned uiHeight, int iInternalFormat, bool bDepthWanted ) { if( uiNumTextures <= 0 ) return false; //generate our variables glGenFramebuffers(1, &m_uifboHandle); // Initialize FBO glBindFramebuffer(GL_FRAMEBUFFER, m_uifboHandle); m_uiNumTextures = uiNumTextures; if( bDepthWanted ) m_uiNumTextures += 1; m_uiTextureHandle = new unsigned int[uiNumTextures]; glGenTextures( uiNumTextures, m_uiTextureHandle ); for( unsigned x = 0; x < uiNumTextures-1; ++x ) { glBindTexture( GL_TEXTURE_2D, m_uiTextureHandle[x]); // Reserve space for our 2D render target glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, iInternalFormat, uiWidth, uiHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL); glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + x, GL_TEXTURE_2D, m_uiTextureHandle[x], 0); } //if we need one for depth testing if( bDepthWanted ) { glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, m_uiTextureHandle[uiNumTextures-1], 0); glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, m_uiTextureHandle[uiNumTextures-1], 0);*/ // Must attach texture to framebuffer. Has Stencil and depth glBindRenderbuffer(GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); glRenderbufferStorage(GL_RENDERBUFFER, /*GL_DEPTH_STENCIL*/GL_DEPTH24_STENCIL8, TEXTURE_WIDTH, TEXTURE_HEIGHT ); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_uiTextureHandle[uiNumTextures-1]); } glBindFramebuffer(GL_FRAMEBUFFER, 0); //everything went fine return true; } void CRenderTarget::Bind( const int& iTargetAttachmentLoc, const unsigned& uiWhichTexture, const bool bBindFrameBuffer ) { if( bBindFrameBuffer ) glBindFramebuffer( GL_FRAMEBUFFER, m_uifboHandle ); if( uiWhichTexture < m_uiNumTextures ) glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + iTargetAttachmentLoc, m_uiTextureHandle[uiWhichTexture], 0); } void CRenderTarget::UnBind( void ) { //default our binding glBindFramebuffer( GL_FRAMEBUFFER, 0 ); } //this is all in a test project so here's my straight forward rendering function for testing this render function does basic rendering steps keep in mind i have already tested my textures i have already tested my box thats being rendered all basic rendering works fine its just when i try to render to a texture then display it in a render surface that it does not work. Also I have tested my render surface it is bound exactly to the screen coordinate space void TestRenderSteps( void ) { //Clear the color and the depth glClearColor( 0.0f, 0.0f, 0.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); //bind the shader program glUseProgram( testShader.m_iShaderProgramHandle ); //1) grab the vertex buffer related to our rendering glBindBuffer( GL_ARRAY_BUFFER, CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().GetBufferHandle() ); //2) how our stream will be split here ( 4 bytes position, ..ext ) CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().MapVertexStride(); //3) set the index buffer if needed glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, CIndexBuffer::GetInstance()->GetBufferHandle() ); //send the needed information into the shader testShader.SetWorldMatrix( boxPosition ); testShader.SetViewMatrix( Static_Camera.GetView( ) ); testShader.SetProjectionMatrix( Static_Camera.GetProjection( ) ); testShader.SetDiffuseMap( iTextureID ); testShader.SetNormalMap( iTextureID2 ); GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 }; glDrawBuffers(2, buffers); //bind to our render target //RM_DIFFUSE, RM_NORMAL are enums (0 && 1) renderTarget.Bind( RM_DIFFUSE, 1, true ); renderTarget.Bind( RM_NORMAL, 1, false); //false because buffer is already bound //i clear here just to clear the texture to make it a default value of white //by doing this i can see if what im rendering to my screen is just drawing to the screen //or if its my render target defaulted glClearColor( 1.0f, 1.0f, 1.0f, 1.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); //i have this box object which i draw testBox.Draw(); //the draw call looks like this //my normal rendering works just fine so i know this draw is fine // glDrawElementsBaseVertex( m_sides[x].GetPrimitiveType(), // m_sides[x].GetPrimitiveCount() * 3, // GL_UNSIGNED_INT, // BUFFER_OFFSET(sizeof(unsigned int) * m_sides[x].GetStartIndex()), // m_sides[x].GetStartVertex( ) ); //we unbind the target back to default renderTarget.UnBind(); //i stop mapping my vertex format CVertexBufferManager::GetInstance()->GetPositionNormalTexBuffer().UnMapVertexStride(); //i go back to default in using no shader program glUseProgram( 0 ); //now that everything is drawn to the textures //lets draw our screen surface and pass it our 2 filled out textures //NOW RENDER THE TEXTURES WE COLLECTED TO THE SCREEN QUAD //bind the shader program glUseProgram( testScreenShader.m_iShaderProgramHandle ); //1) grab the vertex buffer related to our rendering glBindBuffer( GL_ARRAY_BUFFER, CVertexBufferManager::GetInstance()->GetPositionTexBuffer().GetBufferHandle() ); //2) how our stream will be split here CVertexBufferManager::GetInstance()->GetPositionTexBuffer().MapVertexStride(); //3) set the index buffer if needed glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, CIndexBuffer::GetInstance()->GetBufferHandle() ); //pass our 2 filled out textures (in the shader im just using the diffuse //i wanted to see if i was rendering anything before i started getting into other techniques testScreenShader.SetDiffuseMap( renderTarget.GetTextureHandle(0) ); //SetDiffuseMap definitions in shader program class testScreenShader.SetNormalMap( renderTarget.GetTextureHandle(1) ); //SetNormalMap definitions in shader program class //DO the draw call drawing our screen rectangle glDrawElementsBaseVertex( m_ScreenRect.GetPrimitiveType(), m_ScreenRect.GetPrimitiveCount() * 3, GL_UNSIGNED_INT, BUFFER_OFFSET(sizeof(unsigned int) * m_ScreenRect.GetStartIndex()), m_ScreenRect.GetStartVertex( ) );*/ //unbind our vertex mapping CVertexBufferManager::GetInstance()->GetPositionTexBuffer().UnMapVertexStride(); //default to no shader program glUseProgram( 0 ); } Last words: 1) I can render my box just fine 2) i can render my screen rect just fine 3) I cannot render my box into a texture then display it into my screen rect 4) This entire project is just a test project I made to test different rendering practices. So excuse any "ugly-ish" unclean code. This was made just on a fly run through when I was trying new test cases.

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  • OpenGL Shader Compile Error

    - by Tomas Cokis
    I'm having a bit of a problem with my code for compiling shaders, namely they both register as failed compiles and no log is received. This is the shader compiling code: /* Make the shader */ Uint size; GLchar* file; loadFileRaw(filePath, file, &size); const char * pFile = file; const GLint pSize = size; newCashe.shader = glCreateShader(shaderType); glShaderSource(newCashe.shader, 1, &pFile, &pSize); glCompileShader(newCashe.shader); GLint shaderCompiled; glGetShaderiv(newCashe.shader, GL_COMPILE_STATUS, &shaderCompiled); if(shaderCompiled == GL_FALSE) { ReportFiler->makeReport("ShaderCasher.cpp", "loadShader()", "Shader did not compile", "The shader " + filePath + " failed to compile, reporting the error - " + OpenGLServices::getShaderLog(newCashe.shader)); } And these are the support functions: bool loadFileRaw(string fileName, char* data, Uint* size) { if (fileName != "") { FILE *file = fopen(fileName.c_str(), "rt"); if (file != NULL) { fseek(file, 0, SEEK_END); *size = ftell(file); rewind(file); if (*size > 0) { data = (char*)malloc(sizeof(char) * (*size + 1)); *size = fread(data, sizeof(char), *size, file); data[*size] = '\0'; } fclose(file); } } return data; } string OpenGLServices::getShaderLog(GLuint obj) { int infologLength = 0; int charsWritten = 0; char *infoLog; glGetShaderiv(obj, GL_INFO_LOG_LENGTH,&infologLength); if (infologLength > 0) { infoLog = (char *)malloc(infologLength); glGetShaderInfoLog(obj, infologLength, &charsWritten, infoLog); string log = infoLog; free(infoLog); return log; } return "<Blank Log>"; } and the shaders I'm loading: void main(void) { gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); } void main(void) { gl_Position = ftransform(); } In short I get From: ShaderCasher.cpp, In: loadShader(), Subject: Shader did not compile Message: The shader Data/Shaders/Standard/standard.vs failed to compile, reporting the error - <Blank Log> for every shader I compile I've tried replacing the file reading with just a hard coded string but I get the same error so there must be something wrong with how I'm compiling them. I have run and compiled example programs with shaders, so I doubt my drivers are the issue, but in any case I'm on a Nvidia 8600m GT. Can anyone help?

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  • OpenGLES GLSL Shader attributes always bound to 0

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

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  • OpenGL Diffuse Lighting Shader Bug?

    - by anon
    The Orange book, section 16.2, lists implementing diffuse lighting as: void main() { vec3 N = normalize(gl_NormalMatrix * gl_Normal); vec4 V = gl_ModelViewMatrix * gl_vertex; vec3 L = normalize(lightPos - V.xyz); gl_FrontColor = gl_Color * vec4(max(0.0, dot(N, L)); } However, when I run this, the lighting changes when I move my camera. On the other hand, when I change vec3 N = normalize(gl_NormalMatrix * gl_Normal); to vec3 N = normalize(gl_Normal); I get diffuse lighting that works like the fixed pipeline. What is this gl_NormalMatrix, what did removing it do, ... and is this a bug in the orange book ... or am I setting up my OpenGl code improperly?

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  • OpenGL 3.3 different colours with fragment shader [solved]

    - by Andrew Seymour
    I'm an OpenGL newbie. I'm trying to colour 3 circles but only 3 white circles are appearing. n is 3 in this example. Each vertice has 5 points, 2 for position and 3 for color Here is where I think a problem may lie: glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glVertexAttribPointer( 0, 2, GL_FLOAT, GL_FALSE, 5*sizeof(float), (void*)0 ); glEnableVertexAttribArray(1); glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE, 5*sizeof(float), (void*)(2*sizeof(float)) ); glDrawElements(GL_TRIANGLES, 20 * 3 * n, GL_UNSIGNED_INT, 0); glDisableVertexAttribArray(0); glDisableVertexAttribArray(1); My shaders: #version 330 core in vec3 Color; out vec4 outColor; void main() { outColor = vec4(Color, 1.0); } #version 330 core layout(location = 0) in vec2 position; layout(location = 1) in vec3 color out vec3 Color void main(){ gl_Position = vec4(position, 0.0, 1.0); Color = color; } Thanks for taking a look Andy EDIT: layout(location = 1) in vec3 color out vec3 Color layout(location = 1) in vec3 color; out vec3 Color;

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  • Software to capture 3d geometry?

    - by user712092
    Programs I found I found these programs to capture OpenGL 3D scene : 3D Ripper, OpenGL and D3D geometry capture, there are some solved problems with 3D Ripper GLIntercept captures OpenGL function calls OpenGL Extractor captures 3d geometry; should work as plugin for GLIntercept another tool to capture OpenGL 3D data EDIT: There is also HijackGL which changes how a scene is rendered so it probably can be used to capture geometry; it is backed up by a academic paper; it is just just a nice program, not related to what I want i think (or it would might be hard to change it to be for what I want, because it would require programming). 3D Ripper captures geometry, textures and shaders. OpenGL Extractor captures just geometry ... General questions about such programs What is Your experience with these programs? Which of these programs would You recommmend? Do You know other such programs? Were there any problems with them, or are there problems with them in general? Are there programs which work best overall, or is it specific to certain 3d applications? What I need to do? I am looking to program which can capture 3d geometry for study purposes. And also for a program to capture 3D animation (frames of 3d animation). I tried only 3D Ripper because application I try to capture data from is on Direct 3D. 3D Ripper works with at least Direct 3D 9, this application has Direct 3D 6. Are there applications which work with older version of Direct 3D? Thank You very much. :) (I was verbose in link names because I want them to be indexed better by search engines.)

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  • An implementation of Sharir's or Aurenhammer's deterministic algorithm for calculating the intersect

    - by RGrey
    The problem of finding the intersection/union of 'N' discs/circles on a flat plane was first proposed by M. I. Shamos in his 1978 thesis: Shamos, M. I. “Computational Geometry” Ph.D. thesis, Yale Univ., New Haven, CT 1978. Since then, in 1985, Micha Sharir presented an O(n log2n) time and O(n) space deterministic algorithm for the disc intersection/union problem (based on modified Voronoi diagrams): Sharir, M. Intersection and closest-pair problems for a set of planar discs. SIAM .J Comput. 14 (1985), pp. 448-468. In 1988, Franz Aurenhammer presented a more efficient O(n log n) time and O(n) space algorithm for circle intersection/union using power diagrams (generalizations of Voronoi diagrams): Aurenhammer, F. Improved algorithms for discs and balls using power diagrams. Journal of Algorithms 9 (1985), pp. 151-161. Earlier in 1983, Paul G. Spirakis also presented an O(n^2) time deterministic algorithm, and an O(n) probabilistic algorithm: Spirakis, P.G. Very Fast Algorithms for the Area of the Union of Many Circles. Rep. 98, Dept. Comput. Sci., Courant Institute, New York University, 1983. I've been searching for any implementations of the algorithms above, focusing on computational geometry packages, and I haven't found anything yet. As neither appear trivial to put into practice, it would be really neat if someone could point me in the right direction!

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  • Need help transforming DirectX 9 skybox hlsl shader to DirectX 11

    - by J2V
    I am in the middle of implementing a skybox to my game. I have been following this tutorial http://rbwhitaker.wikidot.com/skyboxes-2. I am using MonoGame as a framework and in order to support both Windows and Windows 8 metro I need to compile the shader with pixel and vertex shader 4. compile vs_4_0_level_9_1 compile ps_4_0_level_9_1 However some of the hlsl syntax has been updated with DX10 and DX11. I need to update this hlsl code: float4x4 World; float4x4 View; float4x4 Projection; float3 CameraPosition; Texture SkyBoxTexture; samplerCUBE SkyBoxSampler = sampler_state { texture = <SkyBoxTexture>; magfilter = LINEAR; minfilter = LINEAR; mipfilter = LINEAR; AddressU = Mirror; AddressV = Mirror; }; struct VertexShaderInput { float4 Position : POSITION0; }; struct VertexShaderOutput { float4 Position : POSITION0; float3 TextureCoordinate : TEXCOORD0; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { VertexShaderOutput output; float4 worldPosition = mul(input.Position, World); float4 viewPosition = mul(worldPosition, View); output.Position = mul(viewPosition, Projection); float4 VertexPosition = mul(input.Position, World); output.TextureCoordinate = VertexPosition - CameraPosition; return output; } float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { return texCUBE(SkyBoxSampler, normalize(input.TextureCoordinate)); } technique Skybox { pass Pass1 { VertexShader = compile vs_2_0 VertexShaderFunction(); PixelShader = compile ps_2_0 PixelShaderFunction(); } } I quess I need to change Texture into TextureCube, change sampler, swap texCUBE() with TextureCube.Sample() and change PixelShader return semantic to SV_Target0. I'm very new in shader languages and any help is appreciated!

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  • Monogame - Shader parameters missing

    - by Layoric
    I am currently working on a simple game that I am building in Windows 8 using MonoGame (develop3d). I am using some shader code from a tutorial (made by Charles Humphrey) and having an issue populating a 'texture' parameter. I'm not well versed writing shaders, so this might be caused by a more obvious problem. I have debugged through MonoGame's Content processor to see how this shader is being parsed, all the non 'texture' parameters are there and look to be loading correctly. Shader code below #include "PPVertexShader.fxh" float2 lightScreenPosition; float4x4 matVP; float2 halfPixel; float SunSize; texture flare; sampler2D Scene: register(s0){ AddressU = Clamp; AddressV = Clamp; }; sampler Flare = sampler_state { Texture = (flare); AddressU = CLAMP; AddressV = CLAMP; }; float4 LightSourceMaskPS(float2 texCoord : TEXCOORD0 ) : COLOR0 { texCoord -= halfPixel; // Get the scene float4 col = 0; // Find the suns position in the world and map it to the screen space. float2 coord; float size = SunSize / 1; float2 center = lightScreenPosition; coord = .5 - (texCoord - center) / size * .5; col += (pow(tex2D(Flare,coord),2) * 1) * 2; return col * tex2D(Scene,texCoord); } technique LightSourceMask { pass p0 { VertexShader = compile vs_4_0 VertexShaderFunction(); PixelShader = compile ps_4_0 LightSourceMaskPS(); } } I've removed default values as they are currently not support in MonoGame and also changed ps and vs to v4 instead of 2. Could this be causing the issue? As I debug through 'DXConstantBufferData' constructor (from within the MonoGameContentProcessing project) I find that the 'flare' parameter does not exist. All others seem to be getting created fine. Any help would be appreciated.

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  • What is a better abstraction layer for D3D9 and OpenGL vertex data management?

    - by Sam Hocevar
    My rendering code has always been OpenGL. I now need to support a platform that does not have OpenGL, so I have to add an abstraction layer that wraps OpenGL and Direct3D 9. I will support Direct3D 11 later. TL;DR: the differences between OpenGL and Direct3D cause redundancy for the programmer, and the data layout feels flaky. For now, my API works a bit like this. This is how a shader is created: Shader *shader = Shader::Create( " ... GLSL vertex shader ... ", " ... GLSL pixel shader ... ", " ... HLSL vertex shader ... ", " ... HLSL pixel shader ... "); ShaderAttrib a1 = shader->GetAttribLocation("Point", VertexUsage::Position, 0); ShaderAttrib a2 = shader->GetAttribLocation("TexCoord", VertexUsage::TexCoord, 0); ShaderAttrib a3 = shader->GetAttribLocation("Data", VertexUsage::TexCoord, 1); ShaderUniform u1 = shader->GetUniformLocation("WorldMatrix"); ShaderUniform u2 = shader->GetUniformLocation("Zoom"); There is already a problem here: once a Direct3D shader is compiled, there is no way to query an input attribute by its name; apparently only the semantics stay meaningful. This is why GetAttribLocation has these extra arguments, which get hidden in ShaderAttrib. Now this is how I create a vertex declaration and two vertex buffers: VertexDeclaration *decl = VertexDeclaration::Create( VertexStream<vec3,vec2>(VertexUsage::Position, 0, VertexUsage::TexCoord, 0), VertexStream<vec4>(VertexUsage::TexCoord, 1)); VertexBuffer *vb1 = new VertexBuffer(NUM * (sizeof(vec3) + sizeof(vec2)); VertexBuffer *vb2 = new VertexBuffer(NUM * sizeof(vec4)); Another problem: the information VertexUsage::Position, 0 is totally useless to the OpenGL/GLSL backend because it does not care about semantics. Once the vertex buffers have been filled with or pointed at data, this is the rendering code: shader->Bind(); shader->SetUniform(u1, GetWorldMatrix()); shader->SetUniform(u2, blah); decl->Bind(); decl->SetStream(vb1, a1, a2); decl->SetStream(vb2, a3); decl->DrawPrimitives(VertexPrimitive::Triangle, NUM / 3); decl->Unbind(); shader->Unbind(); You see that decl is a bit more than just a D3D-like vertex declaration, it kinda takes care of rendering as well. Does this make sense at all? What would be a cleaner design? Or a good source of inspiration?

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  • Low-level GPU code and Shader Compilation

    - by ktodisco
    Bear with me, because I will raise several questions at once. I still feel, though, that overall this can be treated as one question that may be answered succinctly. I recently dove into solidifying my understanding of the assembly language, low-level memory operations, CPU structure, and program optimizations. This also sparked my interest in how higher-level shading languages, GLSL and HLSL in particular, are compiled and optimized, as well as what formats they are reduced to before machine code is generated (assuming they are not converted directly into machine code). After a bit of research into this, the best resource I've found is this presentation from ATI about the compilation of and optimizations for HLSL. I also found sample ARB assembly code. This sort of addressed my original curiosity, but it raised several other questions. The assembler code in the ATI presentation seems like it contains instructions specifically targeted for the GPU, but is this merely a hypothetical example created for the purpose of conceptual understanding, or is this code really generated during shader compilation? If so, is it possible to inspect it, or even write it in place of the higher-level syntax? My initial searches for an answer to the last question tell me that this may be disallowed, but I have not dug too deep yet. Also, along the same lines, are GLSL shader programs compiled into ARB assembly code before machine code is generated, and is it possible to write direct ARB assembly? Lastly, and perhaps what I am most interested in finding out: are there comprehensive resources on shader compilation and low-level GPU code? I have been unable to find any thus far. I ask simply because I am curious :)

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  • Proper way to encapsulate a Shader into different modules

    - by y7haar
    I am planning to build a Shader system which can be accessed through different components/modules in C++. Each component has its own functionality like transform-relevated stuff (handle the MVP matrix, ...), texture handler, light calculation, etc... So here's an example: I would like to display an object which has a texture and a toon shading material applied and it should be moveable. So I could write ONE shading program that handles all 3 functionalities and they are accessed through 3 different components (texture-handler, toon-shading, transform). This means I have to take care of feeding a GLSL shader with different uniforms/attributes. This implies to know all necessary uniform locations and attribute locations, that the GLSL shader owns. And it would also necessary to provide different algorithms to calculate the value for each input variable. Similar functions would be grouped together in one component. A possible way would be, to wrap all shaders in a own definition file written in JSON/XML and parse that file in C++ to get all input members and create and compile the resulting GLSL. But maybe there is another way that is not so complex? So I'm searching for a way to build a system like that, but I'm not sure yet which is the best approach.

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  • How can I go about learning to write a shader

    - by Donutz
    So here's the background: I'm writing a game, just for my own amusement and education really. I've already come to the conclusion that XNA was the way to go for graphics, I've bought a couple of books, I've gotten basic game graphics going, and that's great. Now I'm starting to get a little in-depth and I'm starting to need to do stuff not covered in my (beginner) books. In particular, I need to display a sprite using a mask. Actually, what I need to do is display a generic sprite with a different color for each player. After banging around on the web, it seems the way to go is to have a color texture (one for each player) which I display using the mask, then display the generic part of the sprite. This has to be done dynamically, i.e. at runtime because there are too many sprites to keep in memory if I try to generate all the permutations at startup. So, I need to use a shader. Fine. I've downloaded a sample shader program, and managed to hit it with a hammer until it does something close enough to what I want so that I know I'm on the right track. And here, we come to my problem... I have no friggin' clue what I'm doing. While there are a lot of samples and such about shaders, no one ever actually explains what's going on. For instance, I can't find any real docs on Tex2D. I feel like the guys in Zoolander poking at the computer. So, my question (yes, I have a question) -- where is a good URL or what is a good book to take me from dumskie to reasonably competent to write a basic shader?

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  • XNA 4.0 - Normal mapping shader - strange texture artifacts

    - by Taylor
    I recently started using custom shader. Shader can do diffuse and specular lighting and normal mapping. But normal mapping is causing really ugly artifacts (some sort of pixeling noise) for textures in greater distance. It looks like this: Image link This is HLSL code: // Matrix float4x4 World : World; float4x4 View : View; float4x4 Projection : Projection; //Textury texture2D ColorMap; sampler2D ColorMapSampler = sampler_state { Texture = <ColorMap>; MinFilter = Anisotropic; MagFilter = Linear; MipFilter = Linear; MaxAnisotropy = 16; }; texture2D NormalMap; sampler2D NormalMapSampler = sampler_state { Texture = <NormalMap>; MinFilter = Anisotropic; MagFilter = Linear; MipFilter = Linear; MaxAnisotropy = 16; }; // Light float4 AmbientColor : Color; float AmbientIntensity; float3 DiffuseDirection : LightPosition; float4 DiffuseColor : Color; float DiffuseIntensity; float4 SpecularColor : Color; float3 CameraPosition : CameraPosition; float Shininess; // The input for the VertexShader struct VertexShaderInput { float4 Position : POSITION0; float2 TexCoord : TEXCOORD0; float3 Normal : NORMAL0; float3 Binormal : BINORMAL0; float3 Tangent : TANGENT0; }; // The output from the vertex shader, used for later processing struct VertexShaderOutput { float4 Position : POSITION0; float2 TexCoord : TEXCOORD0; float3 View : TEXCOORD1; float3x3 WorldToTangentSpace : TEXCOORD2; }; // The VertexShader. VertexShaderOutput VertexShaderFunction(VertexShaderInput input, float3 Normal : NORMAL) { VertexShaderOutput output; float4 worldPosition = mul(input.Position, World); float4 viewPosition = mul(worldPosition, View); output.Position = mul(viewPosition, Projection); output.TexCoord = input.TexCoord; output.WorldToTangentSpace[0] = mul(normalize(input.Tangent), World); output.WorldToTangentSpace[1] = mul(normalize(input.Binormal), World); output.WorldToTangentSpace[2] = mul(normalize(input.Normal), World); output.View = normalize(float4(CameraPosition,1.0) - worldPosition); return output; } // The Pixel Shader float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { float4 color = tex2D(ColorMapSampler, input.TexCoord); float3 normalMap = 2.0 *(tex2D(NormalMapSampler, input.TexCoord)) - 1.0; normalMap = normalize(mul(normalMap, input.WorldToTangentSpace)); float4 normal = float4(normalMap,1.0); float4 diffuse = saturate(dot(-DiffuseDirection,normal)); float4 reflect = normalize(2*diffuse*normal-float4(DiffuseDirection,1.0)); float4 specular = pow(saturate(dot(reflect,input.View)), Shininess); return color * AmbientColor * AmbientIntensity + color * DiffuseIntensity * DiffuseColor * diffuse + color * SpecularColor * specular; } // Techniques technique Lighting { pass Pass1 { VertexShader = compile vs_2_0 VertexShaderFunction(); PixelShader = compile ps_2_0 PixelShaderFunction(); } } Any advice? Thanks!

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  • Encode two integers into colour values and compare them in a HLSL shader

    - by Ben Slinger
    I am writing a 2D point and click adventure game in Monogame, and I'd like to be able to create an image mask for every room which defines which parts of the background a character can walk behind, and at which Y value a character needs to be at for the background to be drawn above the character. I haven't done any shader work before but after doing some reading I thought the following solution should work: Create a mask for the room with different walk behind areas painted in a colour that defines the baseline Y value (Walk Behind Mask) Render all objects to a RenderTarget2D (Base Texture) Render all objects to a different RenderTarget2D, but changing every pixel of each object to a colour that defines its Y value (Position Mask) Pass these two textures plus the image mask into the shader, and for each pixel compare the colour of the image mask to the colour of the Position Mask to the Walk Behind Mask - if the Position Mask pixel is larger (thus lower on the screen and closer to the camera) than the Walk Behind Mask, draw the pixel from the Base Texture, otherwise draw a transparent pixel (allowing the background to show through). I've got it mostly working, but I'm having trouble packing and unpacking the Y values into colours and retrieving them correctly in the shader. Here are some code examples of how I'm doing it so far: (When drawing to the Position Mask RenderTarget2D) Color posColor = new Color(((int)Position.Y >> 16) & 255, ((int)Position.Y >> 8) & 255, (int)Position.Y & 255); So as far as I can tell, this should be taking the first 3 bytes of the position integer and encoding them into a 4 byte colour (ignoring the alpha as the 4th byte). This seems to work fine, as when my character is at Y = 600, the resulting Color from this is: {[Color: R=0, G=2, B=88, A=255, PackedValue=4283957760]}. I then have an area in my Walk Behind Mask that I only want the character to be displayed behind if his Y value is lower than 655, so I've painted it with R=0, G=2, B=143, A=255. Now, I think I have the shader OK as well, here's what I have: sampler BaseTexture : register(s0); sampler MaskTexture : register(s1); sampler PositionTexture : register(s2); float4 mask( float2 coords : TEXCOORD0 ) : COLOR0 { float4 color = tex2D(BaseTexture, coords); float4 maskColor = tex2D(MaskTexture, coords); float4 positionColor = tex2D(PositionTexture, coords); float maskCompare = (maskColor.r * pow(2,24)) + (maskColor.g * pow(2,16)) + (maskColor.b * pow(2,8)); float positionCompare = (positionColor.r * pow(2,24)) + (positionColor.g * pow(2,16)) + (positionColor.b * pow(2,8)); return positionCompare < maskCompare ? float4(0,0,0,0) : color; } technique Technique1 { pass NoEffect { PixelShader = compile ps_3_0 mask(); } } This isn't working, however - currently all characters are displayed behind the walk behind area, regardless of their Y value. I tried printing out some debug info by grabbing the pixel from both the Position Mask and the Walk Under Mask under the current mouse position, and it seems like maybe the colours aren't being rendered to the Position Mask correctly? When calculating the colour in that code above I'm getting R=0, G=2, B=88, A=255, but when I mouseover my character I get R=0, G=0, B=30, A=255. Any ideas what I'm doing wrong? It seems like maybe I'm losing some information when rendering to the RenderTarget2D, but I'm now knowledgeable enough to figure out what's happening. Also, I should probably ask, is this an efficient way to do this? Will there be a performance impact? Edit: Whoops, turns out there was a bug that I'd introduced myself, I was drawing out the Position Mask with the position Color, left over from some early testing I was doing. So this solution is working perfectly, though I'm still interested in whether this is an efficient solution performance wise.

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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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  • Why can't a blendShader sample anything but the current coordinate of the background image?

    - by Triynko
    In Flash, you can set a DisplayObject's blendShader property to a pixel shader (flash.shaders.Shader class). The mechanism is nice, because Flash automatically provides your Shader with two input images, including the background surface and the foreground display object's bitmap. The problem is that at runtime, the shader doesn't allow you to sample the background anywhere but under the current output coordinate. If you try to sample other coordinates, it just returns the color of the current coordinate instead, ignoring the coordinates you specified. This seems to occur only at runtime, because it works properly in the Pixel Bender toolkit. This limitation makes it impossible to simulate, for example, the Aero Glass effect in Windows Vista/7, because you cannot sample the background properly for blurring. I must mention that it is possible to create the effect in Flash through manual composition techniques, but it's hard to determine when it actually needs updated, because Flash does not provide information about when a particular area of the screen or a particular display object needs re-rendered. For example, you may have a fixed glass surface with objects moving underneath it that don't dispatch events when they move. The only alternative is to re-render the glass bar every frame, which is inefficient, which is why I am trying to do it through a blendShader so Flash determines when it needs rendered automatically. Is there a technical reason for this limitation, or is it an oversight of some sort? Does anyone know of a workaround, or a way I could provide my manual composition implementation with information about when it needs re-rendered? The limitation is mentioned with no explanation in the last note in this page: http://help.adobe.com/en_US/as3/dev/WSB19E965E-CCD2-4174-8077-8E5D0141A4A8.html It says: "Note: When a Pixel Bender shader program is run as a blend in Flash Player or AIR, the sampling and outCoord() functions behave differently than in other contexts.In a blend, a sampling function will always return the current pixel being evaluated by the shader. You cannot, for example, use add an offset to outCoord() in order to sample a neighboring pixel. Likewise, if you use the outCoord() function outside a sampling function, its coordinates always evaluate to 0. You cannot, for example, use the position of a pixel to influence how the blended images are combined."

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  • GLSL shader render to texture not saving alpha value

    - by quadelirus
    I am rendering to a texture using a GLSL shader and then sending that texture as input to a second shader. For the first texture I am using RGB channels to send color data to the second GLSL shader, but I want to use the alpha channel to send a floating point number that the second shader will use as part of its program. The problem is that when I read the texture in the second shader the alpha value is always 1.0. I tested this in the following way: at the end of the first shader I did this: gl_FragColor(r, g, b, 0.1); and then in the second texture I read the value of the first texture using something along the lines of vec4 f = texture2D(previous_tex, pos); if (f.a != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } No pixels in my output are black, whereas if I change the above code to read gl_FragColor(r, g, 0.1, 1.0); //Notice I'm now sending 0.1 for blue and in the second shader vec4 f = texture2D(previous_tex, pos); if (f.b != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } All the appropriate pixels are black. This means that for some reason when I set the alpha value to something other than 1.0 in the first shader and render to a texture, it is still seen as being 1.0 by the second shader. Before I render to texture I glDisable(GL_BLEND); It seems pretty clear to me that the problem has to do with OpenGL handling alpha values in some way that isn't obvious to me since I can use the blue channel in the way I want, and figured someone out there will instantly see the problem.

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  • How do I get the current color of a fragment?

    - by Mason Wheeler
    I'm trying to wrap my head around shaders in GLSL, and I've found some useful resources and tutorials, but I keep running into a wall for something that ought to be fundamental and trivial: how does my fragment shader retrieve the color of the current fragment? You set the final color by saying gl_FragColor = whatever, but apparently that's an output-only value. How do you get the original color of the input so you can perform calculations on it? That's got to be in a variable somewhere, but if anyone out there knows its name, they don't seem to have recorded it in any tutorial or documentation that I've run across so far, and it's driving me up the wall.

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  • When can a freely moving sphere escape from a ‘cage’ defined by a set of impassible coordinates?

    - by RGrey
    Hopefully there are some computational geometry folks here who can help me out with the following problem - Please imagine that I take a freely moving ball in 3-space and create a 'cage' around it by defining a set of impassible coordinates, Sc (i.e. points in 3-space that no part of the diffusing ball is allowed to overlap). These points reside within the volume, V(cage), of some larger sphere, where V(cage) V(ball). Provided the set of impassible coordinates, Sc, is there a computationally efficient and/or nice way to determine if the ball can ever escape the cage?

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  • Strange ATI vs Nvidia TRIANGLE_STRIP issue

    - by chriscisco
    I have this code, I am using a test for my Engine I am working on. On My NVIDIA NVS 4200M it displays the GL_TRIANGLE_STRIP as expected. On my ATI Radeon 5800 it appears to draw a Triangle. shader.begin(); Matrix4<float> temp = getActiveCamera()->getProjectionMatrix() * getActiveCamera()->getObjectToWorld().fastInverse(); glUniformMatrix4fv(shader["mvp"], 1, GL_TRUE, temp.getArray()); glBegin(GL_TRIANGLE_STRIP); glVertexAttrib3f(shader["colour"],0,1,0); glVertexAttrib3f(shader["coord3d"],-.5,-.5,0); glVertexAttrib3f(shader["colour"],1,1,0); glVertexAttrib3f(shader["coord3d"],0.5,-.5,0); glVertexAttrib3f(shader["colour"],1,0,1); glVertexAttrib3f(shader["coord3d"],-.5,.5,0); glVertexAttrib3f(shader["colour"],0,1,1); glVertexAttrib3f(shader["coord3d"],.5,.5,0); glEnd(); shader.end(); Here are what it actually looks like on my two computers. https://www.dropbox.com/s/sgm2j978tx2ipnp/not%20working.png https://www.dropbox.com/s/27idv0b8k0p4pcx/working.png

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  • Fragment shader seems to floor() imprecisely

    - by Peter K.
    I'm trying to interpolate coordinates in my fragment shader. Unfortunately if close to the upper edge the interpolated value of fVertexInteger seems to be rounded up instead of beeing floored. This happens above approximately fVertexInteger >= x.97. Example: floor(64.7) returns 64.0 -- correct floor(64.98) returns 65.0 -- incorrect The same happens on ceiling close above x.0, where ceil(65.02) returns 65.0 instead of 66.0. Q: Any ideas how to solve this? Note: GL ES 2.0 with GLSL 1.0 highp floats are not supported in fragment shaders on my hardware flat varying hasn't been a solution, because I'm drawing TRIANGLE_STRIP and can't redeclare the provoking vertex (only OpenGL 3.2+) Fragment Shader: varying float fVertexInteger; varying float fVertexFraction; void main() { // Fix vertex integer fixedVertexInteger = floor(fVertexInteger); // Fragment color gl_FragColor = vec4( fixedVertexInteger / 65025.0, fract(fixedVertexInteger / 255.0), fVertexFraction, 1.0 ); }

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