Hugo wrote:
> 
> > I just converted the scene geometry to an iso_rcsg function
> > and this way can check any time how near the different balls
> > are to the surface.
> 
> Interesting project you're having! Forgive my ignorance but how do you get
> an output of the isosurface evaluation, for a point within the bounding
> object? 

I don't understand, you can evaluate an isosurface function wherever you
like.

> With the geometry in your example, is it really faster than using
> primitives and individual col. testing?

That's a difficult question.  

Some arguments for the elasticity model are:
- easier to program and to extend to arbitrary geometries.  
- with collision testing you can't modell soft collisions at all.
- it is surely faster for environment collisions than calculating the
distance to all planes forming the geometry by hand which would be
necessary to truly test for collisions (just tracing in direction of
movement is obviously not enough) 
- edges are a serious problem with collision modelling.  The movement of a
ball hitting the edge of an object is not defined since you can't
calculate the normal at the edge.  

On the other hand you can use fairly large integration steps when using
collision calculation since the collision itself is not part of the
differential equation you are trying to solve.  With elasticity you have
to use fairly small steps to get realistic results.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______

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