Sampling unsigned integers from 1D texture using integer texture coordinates - c

Question

I want to pass a big array of unsigned short tuples (rect geometries) to my Fragment Shader and be able to sample them as-is using integer texture coordinates, to do this I'm trying with a 1D texture as follows, but get just blank (0) values.
Texture creation and initialization:
GLushort data[128][2];
// omitted array initialization
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_1D, tex);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAX_LEVEL, 0);
glTexImage1D(
GL_TEXTURE_1D,
0,
GL_RG16UI,
128,
0,
GL_RG_INTEGER,
GL_UNSIGNED_SHORT,
data
);
Texture passing to shader:
int tex_unit = 0;
glActiveTexture(GL_TEXTURE0 + tex_unit);
glBindTexture(GL_TEXTURE_1D, tex);
glUniform1iv(loc, 1, &tex_unit);
Debug fragment shader:
#version 330 core
out vec4 out_color;
uniform usampler1D tex;
void main()
{
uvec4 rect = texelFetch(tex, 70, 0);
uint w = rect.r;
uint h = rect.g;
out_color = w > 0u ? vec4(1) : vec4(0);
}
Things that work for sure: non-zero data in data array, texture image unit setup and sampler uniform initialization.
OpenGL 4.1, OSX 10.11.6 "El Capitan"

Answer 1

After some googling and by trial and error, I discovered this post, which states that with integer texture formats (for example, GL_RG16UI internal format) GL_LINEAR filtering cannot be specified and only GL_NEAREST applies, thus, everything worked out with the following texture creation code:
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_1D, tex);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAX_LEVEL, 0);
glTexImage1D(
GL_TEXTURE_1D,
0,
GL_RG16UI,
128,
0,
GL_RG_INTEGER,
GL_UNSIGNED_BYTE,
data
);