Chambers wrote:
> So I was writing a general particle system capable of spitting out POV-Ray
> code (as SDL solutions are too slow for my tastes), and I found MegaPOV
> with mechsim.  Needless to say, I've been busy playing with it, and find it
> both complete and effective.  Good job on a good patch!

Thanks.

> Anyway, I noticed that I'm still not happy with the simulation speed, so I
> looked at the code for the patch.  Collisions are checked between masses by
> calculating the distance, which requires a sqrt call.  The only way I can
> think of to speed that up is to use a box format first, such as this
> pseudocode:
> 
> if ((abs(dx)<max) and (abs(dy)<max)) and (abs(dz)<max)))
>  if (sqrt(dx^2+dy^2+dz^2)<max)
>   collision is true
>  end
> end

This would be just a bounding box test that would certainly speed up the 
collisions a bit but would not change anything about the principal 
problem of mass interactions being O(n^2).  You should have a look at 
what Daniel Jungmann wrote recently (a few threads ago) which was mostly 
meant for mass-face-collisions but also works on mass-mass collisions to 
some extent.

And the sqrt() has to be calculated for all collisions that actually 
occur since the force depends on the distance.

Christoph

-- 
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Last updated 01 May. 2004 _____./\/^>_*_<^\/\.______

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