When glMultiDrawElementsIndirect is used, what is the behavior of gl_PrimitiveID? Does it reset to zero at the beginning of each DrawElementsIndirectCommand executed in the function, or does it start at zero and increment every time a primitive is drawn, until the function is finished?
All of the multi-draw commands are specified to function as if by a sequence of individual draw calls, with the exception of the behavior of gl_DrawID.