Varying Particle Emission Rate?

Is there a way to vary particle emission rate over time? Let’s say I want to do an effect like erupting lava like they show on Nature shows-- the lava fountains up and down unevenly… or even Old Faithful doesn’t just start spraying at a constant rate and then stop… I can’t seem to find any IPOs I can use.

There are actually quite a few other particle effects I’d like to ask about, but I’ll stick with this one question for now.

Thanks for any help!

I think what you want to do is animate an obstacle in front of the flow and have the particles die on impact, like your hand in front of a hose

Or, have two particle systems, one for the normal steam, and the a gusher system for when it gushes.


I’m not entirely sure what you want to do, but it does sound to me like you want to increase and decrease the rate at which particles are created across frames?

If so there is a IPO key called E_Freq which controls how many particles per frame are generated by a particle emitter.

To add the key though the only way I could find, was to select the Particle emitting object and then goto the ipo window, click on the E_Freq key and then left click in the IPO with with the ctrl key held down to add a key point manually. I’m sure there is a better way to do this but I don’t know it sorry.

Attached is a blend file with it setup.

Well I tried to attach it normally but it did’nt work so the above link should work.

The ipo key curve in that file goes from 0 particles per frame up to 25 particles per frame a few times.

If you play the animation you should see it. I made the plane that emits the particles a halo material so it may not be visible in 3d view, but if you render to an animation you should be able to see the affect.

Hope this helps, if its the wrong thing you’re after sorry, as I said not entirely sure what is required.

Terry, Thanks! That was exactly what I was looking for… I just couldn’t find it because I originally had scrolled to the bottom of the IPO list under the “Object” menu, and when I went to the “particle” menu it showed nothing! After you mentioned this again, I checked again, but this time I middle-button scrolled up and lo and behold there was what I was looking for!

I wonder if 2.50 will have a scroll bar in the IPO key listing…

Thanks again!

very cool!