How Do I Determine Volume Penetration?

[whiterau]

Hello!

i'm looking to craft some MEL to detect when one object (shape, whatever) enters/leaves the volume of another. specifically, when an emitter enters a volume it turns on. when it leaves, it turns off. i'd keyframe it, but i have about 50 entering at random intervals/vectors, so that tack won't work.

can someone point me in the right direction? it needs to be a geometric entry/exit, not a bounding entry/exit. if there is a way to have one emitter's particles die on exit of another's volume, that could also work; but i haven't been able to figure out how to link it up as yet.

tia.

WR!

[joojaa]

Use closest point on surface/mesh node and see if the normal is against your point or not.

QUOTE
if there is a way to have one emitter's particles die on exit of another's volume, that could also work; but i haven't been able to figure out how to link it up as yet.

use particle collsion events.

Again your question contains a bit of a misunderstanding. Mel does not do actually do the computational part of maya so you dont in general program things with mel like this, you issue recepies to maya so that the DG solves the problem.

Do doing dg connectiosn is programming maya mel is just a intermediary languiage for racersiong and querrying mayas state at time of build.

[whiterau]

i thought about using closestPointOnMesh, but i wasn't sure how to track whether it was inside the volume or out. all that would do would tell me is whether it had crossed the barrier in our out. so the emitters that began inside would have inverted states as opposed to the ones that began outside the volume. and, again, due to the random nature of this dopey thing... blah blah blah.

the only concern i have with particle collision events, and i'm right away admitting to loose knowledge of the material, is how to get the particles to collide/bounce when inside the volume, and flat out not emit/die instantaneously when they are outside the volume. to my knowledge, the collision events work the other way around. they die on collision inside, but live outside. kapoop.

and thank you for clarifying the proper context of MEL. ironically, i knew this but having done a ton of web programming lately combined with not using it for a long while, i'd forgotten. besides, your explanation is clearer than any i've heard in a long time! thanks!

i've tried to attac a diagram of what i'm trying to do... but i don't know how. this forum is a little weak on inlining images.

i hope i'm not missing any salient points...

WR!