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Fade particles that leave a volume


TeaLeaf

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Hi Guys,

I have some particles emitted into a volume (source POP > Emission Type > Volume), and pushed about using noise. I'd like the particles that leave the volume to fade out over a few frames. I have 2 groups, 1 called inside, that is a group using a bounding object, and another group that is the opposite of this called outside. I can plug outside into a kill pop and they die as expected but I want to avoid them popping off. I know that it has something to do with the lookup in the color pop, but don't know how to capture the frame that the particle joined the group on so I can fade it.

Any help would be apprieciated.

Cheers,

AnDy

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I'm not sure if this is what you are looking for, but I put together an example for you. Simply put, the density of the volume is being mapped to the color.

Jason

Hi Jason,

I've added a simple scene, for some reason my apprentice at work is crashing, but when the red particles leave the box object, I'd like them to fade to black over say 10 frames.

Cheers,

AnDy

fadeLavingVolume.hipnc

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here is a simple example

color POP sets color and Alpha only when particle is created

VOP POP is fading Alpha to 0 in outside group over specified number of frames/seconds

then kill POP kills all particles with zero Alpha

i've changed particle visualization to sprites in display options so you can see fading in viewport

fadeLavingVolume_fix.hipnc

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No need for VOPs for this effect. You can set age to 0 for the inside group and age will begin to increment when particles exit the group. Note that if the particles leave the group and enter it again, age will be set to 0. The expression to create the fade is age/lifespan which normalizes the age of the particles.

Jason

Edit: *gawks at anim's solution*

fadeLeavingVolume_mightcouldb1.hipnc

Edited by mightcouldb1
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