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Xpresso random seed issue
Hi everybody,
in TP preset Standard Emitter there’s a Random node feeded with a random seed taken from PGetData/Random Seed output to randomize e.g. the size of particles. It returns one (not changing with time) random number for each random seed.Why is that if I feed the very same (with same settings of course) Random seed with a Constant node it returns different random numbers every frame?!?
(I’m using a Mograph Matrix as emitter so I need to use the Index number as Random Seed)
Thank you
Corrado -
7 Replies
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what version of C4D? The Random node changed somewhere in there (before 19 certainly) .
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Version 18, I understand this is the normal functioning of the random node (outputting a different number each frame) so the question is: why is keeping the same number in TP Standard Emitter preset? Usually I use a Noise with the empty Time input port (0)
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Random Mode Free or Time (or is that in R18 yet?)
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AFAIU Mode Free returns a different number each frame and each animation, Mode Time returns a different number each frame but same numbers each animation (starting from Frame 0 you get the same sequence of different numbers)
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That’s as far as my understanding goes too. Are you looking to have each particle have a random size for every frame?
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No, I need a fixed random number for each random seed. Strange is this is as it behaves (and how
you would expect it) in TP Standard Emitter preset, having a random but fix speed, life, size for each particle etc.
I like experimenting with tweaked random or noise to drive animations, usually I use a noise node (lately python nodes) with constant time Input to get a fixed random number; different ways to get them in Xpresso I suppose, there’s also one system preset for integers etc.
But not from the Random node apart in TP preset! -
Fastest solution with Xpresso Python node (fixed random number):
import c4d
import randomdef main():
global Output
random.seed(Seed)
Output = random.random()
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