[ODE] Car Simulation(Lots of problems)

[Robson Ito]

Hum..it seens that there is no solution in my case...I
have a building that is represented by a user
mesh..and my car is colliding with it.i dont wanna to
represent the building like a box. If there is no
solution using the user mesh to this problem i think
im in a great trouble. Dont have time now to make the
test u sugest Chris, but i think u are right. Maybe in
the weekend i got some time. thanks.


--- Chris Ledwith <cledwith at d-a-s.com> escreveu: 
> > I'll try to explain the explode problem more
> detailed
> >
> > if i have a car and an object:
> >
> > velocity         wall
> > -------->         |
> >  ______           |
> > |______|          |
> >                 |
> > ------------------------------
> >
> > velocity         wall, but i litte deformation
> > -------->            |
> >  ______              |
> > |______|          |--
> >                 |
> > ------------------------------
> >
> > any idea?
> 
> 
> My understanding of this problem is that instability
> can arise in
> collision resolution due to regions of trimeshes
> that have normals
> pointing in widely different directions (i.e. high
> local curvature). In
> the picture above, the normal of the horizontal part
> points straight up,
> and the vertical part points straight to the left.
> If the box collides
> with the edge in-between, it will momentarily
> interpenetrate triangles on
> both the horizontal and vertical parts. Because the
> normals point in
> greatly different directions, collision is not
> resolved well. The normals
> "fight" each other, and the box will move around
> wildly.
> 
> Try this test: make 3 or 4 cylinders (modeled as
> trimeshes) of different
> radii, and drive your car into each one. You'll find
> that the cylinders
> that have radii smaller than the length of the side
> of the car will give
> you big problems, whereas the cylinders of larger
> radius behave fine. This
> is due to the higher degree of curvature in the
> cylinders of smaller
> radii; the normals of the triangles oppose each
> other more greatly.
> 
> Hope that makes sense...I've run up against this
> problem again and again.
> I'm surprised there's not more discussion about it.
> The way to deal with
> it is to use simpler trimesh representations for
> objects that could
> potentially collide with boxes and such.
> 
> -Chris
> 
>  

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