Re: is the visibility of a Polygon[] exposed?
- To: mathgroup at smc.vnet.net
- Subject: [mg83700] Re: is the visibility of a Polygon[] exposed?
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Wed, 28 Nov 2007 05:43:28 -0500 (EST)
- References: <figuou$foo$1@smc.vnet.net>
Hi, take the normal of the polygon and (since the polyhedron is convex) use only polygon with normals pointing into the viewer. Regards Jens congruentialuminaire at yahoo.com wrote: > Hello Mathematica UG: > > Is it possible for my code to tell if a Polygon (in my graphics > object) is visible? > > I assume that this is based upon (or is affected by) the ViewPoint-> > setting. > > Further, I assume that the kernel is deriving this somewhere to do > rendering. Do I have any access to this? > > If I evaluate: > > q = PolyhedronData["SnubCube"] > > I can see the component Polygon[] and GraphicsComplex[] objects that > make up the Graphics3D[]. I want to make a code decision based on > whether a face is showing. > > TIA. > > Regards..Roger W. >