Hello,

I have a particle system that is raining particles from a source down onto a collider. The particles have instanced geometry whose scale is controlled with pscale.

The behaviour I am looking for is for the pscale to remain at 1 until a particle collides. At this event the particle stops and pscale should scale down from 1 to 0 using the particle's age. I have tried but can't get the correct expression or maybe I'm going about it wrong.

I have attached my attempt. Any help would be gratefully received.

After much trial, error and help reading I managed to solve this with a VOP SOP network that wrangles my pscale.

The pscale starts at 1. If a particle has stopped (collision behaviour) and has a hittime less than the particle age, the following maths is used to generate pscale: 1/(age-hittime). This causes the pscale to decrease and shrink my copied geomerty accordingly.

Got there in the end.