[ODE] Car Simulation(Lots of problems)

[Robson Ito]

HI. Sorry, im late...^^. i was working in another
project and return to the car project just now..in the
weekend. Humm..i made some tests with my car and now i
figure out that if you collide with a large cube, in a
point that two faces are together (edge??, sorry, dont
know how to say it in english) the system sometimes
explode. Is it the same problem u described??? if so,
how can i correty it, cause im using primitives
already. Like u said the collision normals are very
different cause there are 2 faces here. im really
worried cause if i cant solve this problem my game
will have a great bug. 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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