Michael Polis (mfp++at++terrasim.com)
Tue, 13 Jul 1999 11:11:53 -0400
Inventor apparently uses the OpenGL GLU Tesselator to triangulate polygons so that it can correctly draw concave polygons. If the GLU Tesselator decides that the polygon edges intersect, it calls the combine callback to interpolate the coordinates and color of the new vertex at the intersection (see gluTessCallback(3G)). Since no combine callback has been registered, GLU reports an error, which Inventor passes on to the user. The Inventor designers either didn't anticipate that polygons might be self-intersecting or wanted this condition reported as an error. I don't think you can get a hold of the tesselator object to register your own combine callback, so you either have to find and fix the self-intersecting polygon or ignore the error messages and live with the fact that that polygon will be drawn incorrectly.
--- Mike Polis TerraSim, Inc. mfp++at++terrasim.com 4620 Henry Street, Third Floor http://www.terrasim.com Pittsburgh, PA 15213 Phone: (412) 681-3703 FAX: (412) 421-3199
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