Tessellating the union of 2d contours


When using OpenGL to tessellate the union of 2d contours, the result is a bunch of triangles. Is there a way to know which of the original contours each triangle belongs to?

Just to clarify, I’m using a GLUtessellator to tessellate the union of some contours using GLU_TESS_WINDING_POSITIVE winding rule as described in the Red Book. I get the results I want, I was just wondering if there was a way to recover information about which contour (or contours) a resulting triangle is in.