Question

I’m trying to sample an integer texture from my geometry shader running on a GeForce 330m. It seems to return other values than I load into the texture. I use this code (basically) for creating and loading the texture:

glGenTextures( 1, &textureId );
glBindTexture( GL_TEXTURE_2D, textureId );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32I, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTexture( GL_TEXTURE_2D, 0);
glBindTexture( GL_TEXTURE_2D, textureId );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32I, w, h, 0, GL_RGBA, GL_INT, <some 0-initialized large enough buffer>);
glBindTexture( GL_TEXTURE_2D, 0);
glBindTexture( GL_TEXTURE_2D, textureId );
    int data[] = { 3, 0, 36, 400 };
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 3, 1, 1, GL_RGBA, GL_INT, data);
glBindTexture( GL_TEXTURE_2D, 0);

The idea is that one pixel in specific is set to have a w-value of 400. I then use this in my geometry shader:

#version 330
#extension GL_EXT_gpu_shader4 : require
uniform isampler2D models;

void main()
{
   ivec4 modelstats4 = texelFetch2D(models, ivec2(0, 3), 0);
//   ivec4 modelstats4 = ivec4(3, 0, 36, 400);
   if (modelstats4.w > height) {
      // emit something
   }
}

Using the commented-out fixed values that should be equal result in something being emitted (IE, one point). If I use the actual texel fetch it does not return anything. All values that I know of that can have an impact are now hardcoded so I’m at a loss why this doesn’t work. This is not the full code (OO setup, quite a lot to look through) but these are the relevant OpenGL calls with applicable data.

Answer 1

Found the solution through liberal sprinkling of glGetErrors. The error was in every glTexImage in this code example – apparently, for an integer texture you must not use GL_RGBA but GL_RGBA_INTEGER.

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32I, w, h, 0, GL_RGBA_INTEGER, GL_INT, data);

This now works. The texture fetches are also OK.