[ODE] About the calculation on Contact Point in the trimesh-sphere test

[Nguyen Binh]

I don't seem understand what do you mean.
But if you wonder why they use the tris's normal instead of sphere's normal
is simple: They want to push the sphere out of the tri-mesh. Actually,
calculating the normal in collision detecttion is very very tough,
especially for arbitrary tri-mesh. There are more robust way to deal with
convex tri-mesh.

On 11/8/05, ³Â» <chenlu at cad.zju.edu.cn> wrote:
>
> Hello everyone!
>
> When I read the code of calculating the Contact Points between the trimesh
> and the sphere(in "collision_trimesh_internal.cpp"), I found a problem.(Or
> you can consider as triangles and the sphere because a contact point is
> gotten from a triangle and the sphere pair if they intersect each other)
>
> The position of the result contact point is the most close point on the
> triangle to the center of the sphere. The depth is the distance from the
> most close point to the edge of the sphere. But the normal is equal to the
> normal of the triangle! Does it reasonable? If you want to "push" the
> triangle "away" and you can push it on the point, why not along the directon
> of the sphere center to the point? More important, I think it is more
> corresponding to the depth!
>
> Do you think so?
>
> Could anybody explain it to me? Thank you very much!
>
> ===============================================
> ChenLu
> MixClass of Chu Kechen Honor College,
> Computer Science & Technology,
> State Key Lab of CAD&CG,
> Zhejiang University, HangZhou, CHINA
> E-mail:chenlu at cad.zju.edu.cn
>
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>


--
--Binh Nguyen
Computer Science Dept.
Rensselaer Polytechnic Institute
Troy, NY, 12180
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