Freeze/Pause (stop time) Particles

[LFShade]

There are probably a number of ways to do this, but offhand what comes to mind is to take a snapshot of the particle system at the frame you'd like it to freeze on, and key the visibility of both particles and snapshot so that the snapshot becomes visible at the appropriate frame while the particle system disappears. This is assuming the particles do not need to continue in motion after a period of being frozen.

You could always render out the particles in their own pass, duplicate the frame you want them frozen at several times (to make a long hold frame), and composite with the rest of the shot later.

Play with it, I'm sure you'll come up with something:)

[s2a-adamk]

Thanks for reply.
They don't need to continue - but I need to move though them in 3d once paused - so I can't composite them - if I am understanding what you mean by "snapshot"?

a

[LFShade]

snapshot is a tool that captures a mesh of the current state of a deforming object or particle system. You can find it on the tools menu. Just go to the frame you want the particles to freeze at and then use the snapshot utility (make sure it's set to mesh output) to make a "frozen" copy of the particles. Then you'll need to open up track view, assign visibility tracks to the particle system and its snapshot, and key them such that the particle system becomes invisible on the same frame that the snapshot mesh becomes visible. It will probably help to change the visibility channels' controllers to the on/off type to avoid the bezier curve behavior of the default controller (overshoot = bad).

Just as an exercise, you could also make the particles seem to continue their motion after a time by cloning the original particle system, offsetting its start/stop times, and keying its visibility so that it becomes visible when it lines up with the snapshot. You'd have to make the snapshot invisible at that frame for the effect to work.

Make sense?

[s2a-adamk]

Yeah! That will do it.
Thanks!

a

[s2a-adamk]

Uh, ok - what if I am not using a "Particle Studio" system....

Or can I convert the standard system to a Particle Studio system without loosing any settings? (So I don't have to rerender?)

thanks,
a

[Gilgamesh]

I'm not sure if this would work, but what if you added drag and animated the multiplier. You could ramp it way up right when you wanted the particles to stop.

[s2a-adamk]

Thanks for the thought - I tried drag - but it seemed to move all the particles a lot. I think it could be done....

Maybe I didn't try animating at the right frame. I guess my scale / speeds are messed up - because .1 drag was way to much for the speed of the particle system.

a

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