Modulate value over time with relative start frame?

[NNois]

Ok !
So yes your last scene isn't the way to go, dealing with U or V ids that aren't in there place here, like you said it delays the start by taking a wrong input, plus add an extra layer of noise.

Seems you just can use a setup like my last scene (and the last compound) and trigger by the modulate by volume TO the custom step input

[Bullit]

Nopes. Sorry. Modulate by Volume in Custom Step only triggers those outside the volume. Besides, those outside triggered all rotate at same time.

The propose of the volume is to choose precisely those particles in the point cloud that i want SRT, maybe i didn't explained this well. That's the function of volume in this. It is a particle chooser.
Could have been by point ID, odd/even ID, but the volume is the most practical way, it is also a visual way .
With several volumes i can SRT every part of the point cloud how i like in the time i like. The system i have got was already doing this - the volume just started to cover a particle and this particle just SRT* - but i was missing the specific SRT time control that you kindly have been helping with.

*This have advantages and inconvenience, for example it is easier to do a radial effect. I just have to scale up or down a circular volume(sphere cylinder). But i think you said it doesn't make possible to control the speed of SRT.

[NNois]

well i've assumed you understood the logic behind this ;-)
If you haven't cracked this, to be more precise and do what you describe it's quite simple.
It's just about reverting/customising the modulate by volume so he create a custom stepper with falloff etc (like mine in my example scene but in your way), then, after the time modulate thing and the transform, filter the execution with your volume !

[Bullit]

Thanks. I'll look into it. Yesterday was a busy day.