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I'm wanting to create a wave-like effect where particles are emitted from a mesh every X number of frames.

Particle modifiers have a Start and End frame setting, but what if I just want that particle modifier to repeat itself for infinity? I want the particle system to spawn some particles, stop for a set time, then spawn some more particles, creating waves of particles that will keep coming forever.

I don't know how to do this with blender. It is a start and end particle system. That's it. What can I do?

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    $\begingroup$ can you explain better the concept of "infinity"? why do you want a blender animation to last forever? $\endgroup$ – Sanbaldo Jul 19 '20 at 13:58
  • $\begingroup$ I'm trying to create an effect that is like waves. I want waves of particles, so the animation needs to emit particles, stop, and then emit again, and continue doing that for infinity. $\endgroup$ – RBlong2us Jul 19 '20 at 18:02
  • $\begingroup$ What's your desired output? A video that last 1 hour? A looping video? You want to use blender as demo machine? $\endgroup$ – Sanbaldo Jul 19 '20 at 19:07
  • $\begingroup$ I'm making a video that does not loop. I just didn't want to have to duplicate that particle system over and over and change the start/end times to make the wave effect. I think there should be a better to do it. $\endgroup$ – RBlong2us Jul 19 '20 at 19:34
  • $\begingroup$ Do you know animation nodes add-on? $\endgroup$ – Sanbaldo Jul 19 '20 at 22:20
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You can control particles emission with animated Black & White Color influencing an emission Density.

enter image description here

In this example

  • particles are emitted from circle's vertices (but source can be Face or Volume as well)
  • by default are particles emitted all the time
  • with Texture (Color) you can influence density of emitted particles

Technically you don't let blender to stop / start emitting particles, but texture says how much dense particles should be emited. Black color means emit zero particles, White means full density of emitted particles.

Animation Sequence

Go to Particles Properties editor > Texture and ad New. Switch tab to Texture Properties and select type Image, simply because it is black by default, so you don't have to setup nothing else. Just go to Influence panel and enable Density

enter image description here

Now you have two options

  • animate color from black to white or
  • I decided to animate Density parametr from 0 to 1

... means zero influence of black density - it let particle system emit as normal, one means full influence of black density that is zero particles. If it is too overhead you can choose first option and in Texture enable Color Ramp and animate color. Result is the same.

Set one cycle of keyframes and go to Graph editor and change interpolation T to Constant that will works like switch ON/OFF in time.

Animation Repeat

To let blender repeat this animation open Graph's editor properties (side panel) N, go to Modifiers tab and add Cycles

enter image description here

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  • $\begingroup$ This looks like a good answer to my problem. Thanks! I could use more details, though, if you don't mind :) $\endgroup$ – RBlong2us Jul 20 '20 at 5:40
  • $\begingroup$ Great! I'm sure this will work. Thanks for the tip. I have one question: Is there a way to make the particles invisible until "spawned"? $\endgroup$ – RBlong2us Jul 21 '20 at 2:20
  • $\begingroup$ I m going to check if General time or Size helps, but it's wierd they appear anyway. To work with particles is a pain, mainly due a lack of proper cache update. Many changes in setup is ignored and only change of particles number solves this issue. $\endgroup$ – vklidu Jul 21 '20 at 6:11
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Make the last frame the copy of the first one, but mind you: the anim can go forever only in the viewport and timeline until you pause/stop it. Once you rendered it you need to loop-play it with your external player.

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