particle steam bouncing

Hi there

first of all, I really feel bad to post this maybe silly question, but what it is happening doesn’t make much sense to me, and hopefully someone can help me with this and indicate what I am doing wrong.

I am trying to do an effect of laser reflecting to a surface. For that, I am doing a steam of particles which I will convert to a laser by playing with color, material, etc.

The problem is that the particles bounce correctly the first cycle, but not anymore in the next cycles, doing a kind of a weird bouncing. If I change any parameter (just something so simple as changing the number of particles from 1000 to 1001, so very small effect), the first cycle works fine again, but not the following ones.

Could anyone what I am doing wrong? I attach two snapshots of these moments, top one the first cycle, and the bottom one with this weird bouncing.

thanks and sorry for this silly question

when you play the stream animation, blender Caches the particle data into memory, if you make changes to the data, like adding an extra particle, the cached data is no longer consistent with the new data so the effect messes up. simple reset your timeline back to the start each time you make a change then blender can cache the data correctly.

if thats not the problem then we may want to see more info :slight_smile: