Outputf( "vertex shader compile failed\n" ) GlGetShaderiv( vs, GL_COMPILE_STATUS, &result ) GlShaderSource(vs, 1, &vertex_shader, NULL) GlVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL) GlBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), points, GL_STATIC_DRAW) Outputf( "OpenGL version supported %s\n", glGetString( GL_VERSION ) ) Outputf( "Renderer: %s\n", glGetString( GL_RENDERER ) ) Window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL) GlfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE) GlfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE) GlfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3) #if defined( _APPLE_ ) & defined( GLFW_INCLUDE_GLCOREARB ) " val_f = -( intBitsToFloat( val_i ) ) \n" " val_i = floatBitsToInt( ( intBitsToFloat( val_i ) ) * -1.0 ) \n" "#extension GL_ARB_shader_bit_encoding : enable\n" While(( err = glGetError() ) != GL_NO_ERROR ) Void flushGlErrors( const int showGlErrors ) #if( defined( _APPLE_ ) || defined( _linux_ ) )
#if !( defined( _APPLE_ ) || defined( _linux_ ) ) Nvidia_opengl_compiler_problem.c //! uncomment to fix the OGL compiler problme I’ve added a repro case to the bottom of this post that shows the problem, (requires GLFW & GLEW), where the define FIX_OGL_COMPILER_PROBLEM can be used to control the problem. The problem doesn’t appear to occur on OSX, at least on: I’m not sure of this problem’s scope but it seems to occur when using the bit representation functions, scalar floats, (including from uniforms), and source argument modifiers, though of course the scope could be much wider. I’ve confirmed the behaviour with Nsight’s OGL shader debugging. Which then results in val_i containing the expected integer value of the negated float representation. The fix for this problem is to simply introduce a temporary: float val_f = -( intBitsToFloat( val_i ) ) It seems the compiler thinks the bit representation macros can be cancelled out without considering the negative modifier, ie that the following is occurring: val_i = -( val_i ) The result of val_i contains the integer representation of the negated integer representation of the source argument instead of the expected negated float representation. Val_i = floatBitsToInt( -( intBitsToFloat( val_i ) ) ) I think i may have found a problem in Nvidia’s GLSL shader compiler on Windows.
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