Is there a way that every time I pulse the Reset on a ParticlesGpu - that the exact same pattern of random particles / vels etc are generated. This will allow me to render out multiple passes of the same animation - with the exact same particle flow.
Hi @glenn2025,
particlesGPU currently has 2 sources of randomness:
One is the Noise CHOP “noise2” which helps randomize values used for lookups and more.
The second is the uTime uniform specified on the “glslmulti_particles” TOP.
If you turn off timesliceing on the beforehand mentioned Noise CHOP, change the channel length to be a single sample and then drive the Seed parameter with a upward counting value, then you can reset the counting value and the noise will generate the same values again.
Similar replace the uTime value with a time based count that can be reset and the whole system should be fairly deterministic.
Such things can be set up with a Constant CHOP and a Count CHOP for example.
cheers
Markus
thank you so much - will try this !
got round to trying this - but still having problems 
I got the uTime to reset to zero everytime on reset, and I froze the noise 2 chop completely - just for quick testing… but particles still random everytime… I noticed a few other things like lfo turbulence which i switched off, but still don’t know what the source problem is.
Hi @glenn2025,
you are right - just tried also replacing the Hash function with a lookup into a static noise and I still get varying result. This might be due to how the compute shader is processed on the GPU - will investigate and get you an answer.
cheers
Markus
thanks 
really appreciate the help on this forum…
Hi,
I just found this,
It’s exactly what I want - deterministic particles - very clever process…
So I hope I haven’t wasted too much more of your time,
Thanks anyway.
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