[Bf-committers] arbitrary point-inside-manifold-mesh test?

Ed Halley ed at halley.cc
Fri Jan 6 06:01:23 CET 2006

> On 12/23/05, Ed Halley <ed at halley.cc> wrote:
>>I don't see any current code in the codebase that tests if an arbitrary
>>point is inside a given manifold mesh.  Is this correct?
>>If there is no such test, then it seems to me that the appropriate
>>algorithm would be some ray-like thing, like 2d rasterizers, where a ray
>>in an arbitrary direction would have an odd number of face intersections
>>to escape a mesh, but an even number if the ray started from outside the
>>mesh.  Any better ideas?

Filip Svendsen wrote:
> Yeah, that will do it. But what do you need it for? If you have to
> check the same mesh many times, it might be better to find a
> description of the mesh as a disjoint sum of convex meshes.
> This also seems like an obvious problem from collision detection,
> maybe you should mail Erwin?

These are both good ideas.  My initial thought was a render-time check 
to support a new material concept I call "boolean materials" or 
"appliques," but after learning more about the convertScene process, I'm 
not sure it would be feasible.

[ e d @ h a l l e y . c c ]

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