Is it possible to direct emitter to emit 1 particle at a frame and another 1 at latter frame?

[tsaid]

I have positions of bullet holes on a wall geo that I want to add RBD fracture.  What I want to achieve is to create a bullet hole per particle hit at frame 10 and another particle hit at frame 15, and another one at frame 25, for example.  I learned how to set emission on/off between frames but I can't figure out how to control "when" to emit that one.  Animate a small sphere might be more directable but I wonder if there is way to do it with particles.  Thanks for your help!

[Atom]

You can use an expression on the activation field.

Try something like this...

if(($F==10) || ($F==15) || ($F==25),1,0)

The double pipe symbol means "or".

[tsaid]

Thanks for helping out, Atom!  I have the expression set both in Impulse and Const. Activation for testing; however, frame 15 and 25 would both get ignored for some reason.  The expression does make sense to me, to activate at those 3 frames and deactivate at the rest.  Perhaps particle simulation can't be controlled like what I wanted?  I have a simple scene attached with the expression.  I want to emit 1 particle at frame 10 and another 1 particle at frame 15, and another one at frame 25.  Or in this case, how would you approach it?

Question_emitParticleAtFrame.hiplc

[Atom]

On the PopSource you have to set your source emission type to points, not scatter. On the Birth tab place the expression on Impulse Activation, not Constant Activation. Set the impulse count to 1 and constant count to zero.

ap_Question_emitParticleAtFrame.hiplc

Edited December 21, 2020 by Atom