[Bf-committers] questions about particles and collisions

[David Jeske]

Lukas, thanks for your response.

At the root of my puzzling is the question... Is an explicit check to
assure a particle system only collides with a collision modifier on it's
emitter that appears *before* itself sufficient to allow self collisions?
It seems like it might be, and I'm wondering if there is any specific
reason it's not (situations where the collision modifier 'save state' might
be invalidated during the evaluation of modifiers that come after it on the
stack).

I could see how manual initial particle collision avoidance control could
be useful, and it would be pretty easy to add. Is this something artists
would like to have? Likewise, do you know if artists miss the fact that
particles don't currently have support for collision groups?

The applicability of the billiard ball example is lost on me, as afaik,
blender doesn't currently support particle-to-particle collisions.

I should disclaim that I don't have a stance on whether particle-to-emitter
collisions are good to add or not. Some part of me wants them in so to make
blender more consistent, but I recognize that isn't always a good reason to
add the complexity.

For me this is currently a fact-finding mission to better understand
particle-to-emitter collision issues, because I would like to have
hair-to-emitter collisions. They are motivated by an actual use case, whose
value I think is more obvious. However, after experimenting with
hair-to-emitter collisions, it appears that current interpenetration
problems with the cloth/hair sim need to be fixed before hair-to-emitter
collisions would be practically useful.