When using triangle strips, is there any way for the fragment shader to know which triangle it’s in? Does gl_PrimitiveID output per triangle (not per strip)? If so: I’m outputting vertices from a geometry shader, how can I get gl_PrimitiveID specified per-triangle still?
If you are using geometry shader, you can output any per-triangle data using the “flat” modifier for it. Set this variable(s) once just before emitting the last vertex of the triangle.
Thanks! But unfortunately I’ve abandoned the geometry shader - it didn’t seem to play nicely with just about any drivers. Is there any way for the fragment shader to know straight from the vertex shader?
Edit: Sounds like the same rules still apply https://www.opengl.org/discussion_boards/showthread.php/182805-Triangle-Strip-Per-Triangle-color