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

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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