gl_PrimitiveIDIn — contains the index of the current primitive
in int gl_PrimitiveIDIn ;
gl_PrimitiveIDIn is a geometry language input variable that holds
the number of primitives processed by the shader since the current set of rendering
primitives was started. The first primitive processed by the drawing command is numbered
zero and the primitive ID counter is incremented after every individual point, line
or triangle primitive is processed. For triangles drawn in point or line mode, the
primitive ID counter is incremented only once, even through multiple points or lines
may actually be drawn. Restarting a primitive topology using the primitive restart
index has no effect on the primitive ID counter.
|OpenGL Shading Language Version|
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