What he said.
Often randomness and testing values gives unexpected (faulty?) results that
don’t show or matter on large amounts of particles – but they can show on small
numbers or in very precise or controlled situations. If you think your logic is
right and it doesn’t work as expected – it’s worth a look inside the compounds
that are open – see how things are done, and occasionally fix things.
And just because your title was ‘modulo’..
get particle id > modulo by x > select case 0,1,2... > set attribute.
the random possibility node is much more convenient and flexible for
percentages,
but with ‘modulo + select case’ you can do some interesting distributions and
control totally different things at once (by plugging execute nodes in the
cases) eg. every second particle is assigned an instance, 3rd and 7th get a
different color,...
From: Ed Manning
Sent: Monday, April 11, 2016 3:17 PM
To: [email protected]
Subject: Re: Modulo ? Modulo ?
On Mon, Apr 11, 2016 at 6:19 AM, Christopher Crouzet
<[email protected]> wrote:
The 6/4 result is to be expected and is not related to a rounding issue but
simply to the nature of randomness—setting a ratio of 0.5 doesn't guarantee a
50-50% split, it only means that the distribution will tend towards this goal,
especially when the number of samples will be high enough (and 10 samples
definitely isn't much at all).
Yes! ICE factory nodes have inherent problems with small sample sets (precise
numbers of particles). "Generate Sample Set," for example, which lurks within
many factory compounds, but cannot be edited, has this tendency. I think this
is one reason you find so many people who do deterministic particle animations
(e.g. non-simulated ICE trees for strand animations like, say, LKLightning) end
up building their own "emitters" and other compounds from really low-level
components or in C++.
I ran into this recently when trying to use factory nodes to build a very
simplified simulation framework that operated on very small populations of
particles that had to emit at precise locations at precise intervals. Every so
often, I'd get some "missing" particles and some doubled ones. I think this
actually happens in simulations all the time, but we don't care since we're
generally looking for large numbers of particles and statistically-accurate
aggregate behavior rather than precision.
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