In article <397### [at] peakeduee>, Margus Ramst 
<mar### [at] peakeduee> wrote:

> Strange, it sometimes happens without running ipf previously 
> (although that seems to be a sure-fire way). Haven't found the 
> connection yet.

It still sounds like an uninitialized variable or a dangling pointer.


> I see. Actually, I think this is sufficient in most cases, especially 
> with liquids.

Inter-particle collisions would probably just interfere with liquid-like 
behavior.


> As for the "solid" particles - I don't think inter-particle collision 
> and deflection would be at all expensive for spherical particles, and 
> prohibitively expensive for most other shapes.

Actually, the only way I can think of doing it would also work for 
arbitrary shaped objects(like meshes), but would be computationally 
expensive for all of them. I suppose the cheapest one would be a 
triangle, followed by triangle pairs, other simple, non-solid shapes, 
and boxes. Spheres would definitely not be the cheapest.
I definitely need to learn more about rigid body dynamics before I try 
this.


> What physical properties would be needed? Collision is easy, 
> deflection and impact energy absorption too, friction I'm not so sure 
> about... What else?

Impact energy absorption already exists, as elasticity. Friction 
coefficient, shatter speed, geometry, etc. Internally, center of 
gravity, angular velocity, a bounding box...


> BTW, I found an interesting page discussing sorting algorithms for 
> particle systems (specifically kd-trees and Barnes-Hut trees). I saw 
> no actual code, but pretty informative nevertheless. The URL is:
> http://physics.gmu.edu/~large/lr_forces/lr_general.html

Thanks, I will take a look...

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

Post a reply to this message