How does GL handle drawing vertex buffers which contain some zero-area tris (degenerate polygon?)? For example, suppose I have some tris in VBO for which all vertices are just 0,0,0 (E.g. since they were allocated space in the buffer that never got used in marching-cubes algorithm). Will it discard them or are they a significant performance hit? (E.g. suppose there are 10 or 100 times as many zero-area tris as real tris (comprising the isosurface)?)
Is there a way these can be rejected in the pipeline to improve performance, without requiring a return to host?
Will vertex shader instance be invoked for each 0 vertex in each zero-area tri?
Will primitive assembly succeed or can it be forced to fail in this case (how)?