I figured out your problem: you are rendering to the same buffer that you’re sourcing your vertex data. glBindVertexArray(vaoPass2); I think you meant vaoPass1 From the spec: Buffers should not be bound or in use for both transform feedback and other purposes in the GL. Specifically, if a buffer object is simultaneously bound to a … Read more
Look at it practically. First, the fewer matrices you send, the fewer matrices you have to multiply with positions/normals/etc. And therefore, the faster your vertex shaders. So point 1: fewer matrices is better. However, there are certain things you probably need to do. Unless you’re doing 2D rendering or some simple 3D demo-applications, you are … Read more
General rule: If you can pass it to a shader in form of a uniform, always precalculate on the CPU; no exceptions. Calculations on the shader side make sense only for values that vary between vertices and fragments. Everything that’s constant among a whole batch of vertices is most efficiently dealt with on the CPU. … Read more
Variables shared between both examples: GLint i; GLint count; GLint size; // size of the variable GLenum type; // type of the variable (float, vec3 or mat4, etc) const GLsizei bufSize = 16; // maximum name length GLchar name[bufSize]; // variable name in GLSL GLsizei length; // name length Attributes glGetProgramiv(program, GL_ACTIVE_ATTRIBUTES, &count); printf(“Active Attributes: … Read more
I just added filters to my open source GPUImage framework that perform three of the four processing tasks you describe (swirling, sketch filtering, and converting to an oil painting). While I don’t yet have colorspace transforms as filters, I do have the ability to apply a matrix to transform colors. As examples of these filters … Read more
Based on my very limited understanding of what you’re trying to implement, it seems you would need to take the location of the intersection between the eye vector and the interior plane it hits, then trace it back to the light. To trace back to the light, you would first have to check if the … Read more
Yes — in fact it is highly desireable to detach and delete your shader objects as soon as possible. That way the driver can free up all the memory it is using to hold a copy of the shader source and unlinked object code, which can be quite substantial. Measurements I have done indicate that … Read more
You don’t need precision specifiers on constants/literals since those get compile time evaluated to whatever they are being assigned to. In vertex shaders, the following precisions are declared by default: ( 4.5.3 Default Precision Qualifiers) precision highp float; precision highp int; precision lowp sampler2D; precision lowp samplerCube; And in fragment shaders you get: precision mediump … Read more
It flows from the definition of a normal. Suppose you have the normal, N, and a vector, V, a tangent vector at the same position on the object as the normal. Then by definition N·V = 0. Tangent vectors run in the same direction as the surface of an object. So if your surface is … Read more
With c++11, you can also use the new feature of raw string literals. Put this source code in a separate file named shader.vs: R”( #version 420 core void main(void) { gl_Position = vec4(0.0, 0.0, 0.0, 1.0); } )” and then import it as a string like this: const std::string vs_source = #include “shader.vs” ; The … Read more