View Full Version : blobby particles as spurts of blood - collisions?

07 July 2003, 01:57 AM
In an attempt to make a character spurt blood from deep gashes in her face, i've been using vertices on the face as points of emmision.
however, when i try to make the particles collide w/ the geometry, the blobs seem to trickle down the inside of the character rather than on the surface. duplicating a non-renderable template geometry has not been able to produce anything different.
i was just wondering if i could get away with emitting particles from vertices as well as getting accurate collisions w/ the same geometry?
also, this scene becomes almost impossible to work with, resulting in many a crash. is it 'cause im emitting so many particles, and is there any feasible workaround to this problem? (something like 3,000 for rate - about 8 emission points)
the obvious alternative i guess would be to parent emmiters to clusters on the face.

help is most humbly requested.

07 July 2003, 02:38 AM
Man, this is a toughy...

all I can think of at the moment is possible Normal Direction issues of the geometry maybe?

Have you maybe tried a non-renderable "gash" piece of geometry to emit blobbies from?

...just curious:)

07 July 2003, 03:05 AM
that's actually a pretty good idea. im guessing i can parent geometry emitters to clusters, which are in turn parented to proper vertices on character face, correct?

07 July 2003, 03:33 AM
hold on a minute, clusters not moving when the geometry moves... i was unaware it worked like that.
ok, so if i put gash pieces into proper position on the face, then animate head via bones, the gash emitters should keep their proper place (i hope?)

07 July 2003, 03:37 AM
nope, guess i'll just parent gashes to head control bone. but if i were to add influence objects (smooth skin), would they move in proper place with the head, and can i emit from them. probably so, so guess that's what ill do then.
(in case you wanted to know:) )

07 July 2003, 02:09 AM
Sounds like you answered your question then:)

Good luck! Can't wait to see if it worked for ya!

07 July 2003, 02:20 AM
what i don't understand is this - if i scroll through the sequence and stop to render a random frame, it will take about 20 sec or so. but when i batch render a sequence, it takes more like 5 minutes per frame.
this seems a bit inconsistent, no?

07 July 2003, 02:34 AM
Man, that could be a LOT of things like:

Are your Render settings the same for the Batch as opposed to the one-off frame?
i.e, reuse tesseleations, particle cache (if you have one) etc.

Also remember, when Maya does a one-off frame, less overall calculations are done due to the hardware run-up to a given frame, rather than taking the "previous-next frame method" into account.

Maya calculates particle simulations, and to a lesser extent, particle direction based mostly on the previous frame as it determines where to place your particles for that given frame.

so if you ask Maya to do any ONE given frame, the calculations of dynamics, interparticle-collisions (if you use hem), direction, etc. are greatly reduced as the calculation-load is only based on one frame, rather than a sequence of frames in a simulation.

Make sense?

..also, have you run "OPTIMIZE SCENE SIZE" just in case?

...another thing, if you have created a particle cache, and made any changes to a particle simulation, a cache needs to be re-created in order fo you to scrub through the frame range without errors, etc.
(just fyi) :)

07 July 2003, 06:48 AM
ok, good deal, i was thinking it was the dynamics calculations that was probably killing the batch render times. thanks for clearing that up.
i've had to reduce my particle rate from 3000 down to 500, just to keep my computer from being locked down for the next week or so!
i was just underestimating the power of massive particles, i've done some fluid stuff and whatnot, but i guess 8 emitters at a rate of 3000 is pushing it without some kinda render network.

07 July 2003, 10:15 AM
Did you create a particle cache? If yes maya shouldn't calculate the particles when rendering and should be as fast as your one frame render. But beware - those caches can become really huge.
And for the parenting problem try the rivet script from highend which lets you constrain your gashes to 2 edges on your surface - which will result in correct movement if you use smooth skinning or blendshapes.

07 July 2003, 11:37 PM
particel cache would be the solution! for some reason it didn't occur to me that this would affect the render times - thought it was just for real-time previews.
thanks very much!

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