Hello,
Transform feedback doesn’t work when the vertex attribute id=0 is not bound. I’m checking the result via TransformFeedbackPrimitivesWritten query.
If the attribute id=0 is used, then query returns N, what is exactly the number of vertices(=primitives) processed.
If not used, query returns 0 (!), and output buffer is not changed.
Environment:
WinXP, Catalyst 10.5 (the bug has probably appeared in older versions)
OpenGL-3.2 forward-compatible context
The program used in testing:
#version 130
in vec4 at_pos;
out vec4 to_pos;
void main() {
to_pos = vec4(1.0,2.0,3.0,4.0);
}
Experiment here is to change the binding location of at_pos between 0 (working) and 1 (not working).
The TF code, shader initialization and vertex buffer manipulation is well-established and works correctly.
Please, confirm if you experience similar problems.