_newtri.c projects 3-D FLEs into 2D intelligently. If a FLE is planar in three-space, projecting it into two-space preserves its topology, unless it projects onto a plane perpendicular to the FLE plane. I have little doubt that there remain cases that don't triangulate successfully - doing geometric processing in 3D is very prone to error, and its very difficult (or impossible) to anticipate all the cases where weird things happen. You just gotta debug them. Quadrille paper comes in *very* handy.
Greg Randall Hopper <[EMAIL PROTECTED]>@opendx.watson.ibm.com on 11/01/2001 10:49:30 PM Please respond to opendx2-dev@lists.berlios.de Sent by: [EMAIL PROTECTED] To: opendx2-dev@lists.berlios.de cc: Subject: [opendx-dev] Re: 3D models -> DX: Anyone for polygon support? Gregory D Abram: |> 1) self-intersecting loops (e.g. figure 8) |> 2) self-overlapping loops (i.e. edges coincident with other edges) |> 3) different loops intersecting or overlapping each other |> 4) arbitrary planar loop sets in 3D which have no bearing on 2D topology | |Certainly #1 should be fine. I'm not sure about #2, but it obviously could |be made to work. #3 - do you mean loops of the same face? If so, again, |I imagine that it could be made to work. If not, then it should be OK; it |handles separate faces independently. I don't understand the last. Just think random polygons oriented and positioned randomly in 3-space. That's all I was trying to say. I'd gotten the impression from _newtri.c (around the "topology error" spots) that there might be some loop-to-loop overlap/containment problems with this scenario, ...but I haven't examined the module carefully yet. |My point is that the FLE type *should* provide the capabilities you want; |if it doesn't, then we should fix it rather than start over from scratch. ... |Regarding the env var, sure, that can be done by a field attribute. It |certainly shouldn't be done the way it is; this way the env var is accessed |over and over. Ok. I'll look into adding this as soon as I put the current project to bed. I'll also pull out samples that lock up triangulation and that render incorrectly. Thanks for the feedback. Randy -- Randall Hopper [EMAIL PROTECTED]
