Coloring blobby mesh suing particle proximity

[alexx]

basically no problem.
you just use the normalized distance between particles to change their rgbPP using a ramp.

only problem and really slow to compute: you have to calculate the distances for all the particles, which is terrible slow if you got some more..

cheers

alexx

[Vushvush]

Can you please go into a little more detail?

Also, what if I want to use the colors particle to color a surface based on their proximity to said surface? Like, have a particleshape with red and blue particles, and as the particles flow over a surface, their proximity will actually affect that surfaces color?

[alexx]

oh.. i thought you wanted just to color the particles differnetly when they get close to each other...
with the surface that is a lot harder to get..

the bassic approach would be the same as having to surfaces that get close to each other.
only difference should be, that you need an expression to calculate all the particles distances.

on a hint on how to use that information check out the shader:
expression-driven distance shader v1.0
from highend3d.

hmm.. i wonder if that could be done with a 2d fluid texture..
i remember having seen a "pond" like texture, that uses fluids and particle collisions.
but i am not really good with fluids.
maybe search in here for the words "duncan" and "rain".. that should help.

cheers

alexx

[Vushvush]

I'm aware of most of this. My biggest hurdle is how do I get the colors AND positions of all these particles?

if you could help me out, as I'm not sure about most of the syntax/commands it would be VERY helpful.

[alexx]

quite easy..
particeles have their own getAttr command:

getParticleAttr

so to get the position of particle #10:
getParticleAttr -at position particleShape1.pt[10];

for some reason i do not understand at all, that command does not return 3 values, but 6..
so put the result to an array and just use the first 3 ones.

for the color it would be:

getParticleAttr -at rgbPP particleShape1.pt[10];

please keep me updated with what you are doing, since i am interested in the result.. could be way cool

cheers

alexx

[Vushvush]

ok cool, that will help a lot I think.

The deal now, I think, would be using a sampler info node on the surface, and getting the avg RGB value of the particles within a certain distance from that point and assigning those results to the color channel.

More help would be helpful (that was intended)!

[alexx]

sorry.. i have to do a bit of my work that i get paid for, and this is nothing i can directly write down without taking some serious r&d :/

[Vushvush]

Well, this is deffinitly a little over my head :)

Where I currently stand, I'm trying to use the distanceBetween technique of coloring a surface to try and color the surface as the particles go over it.

The thing I can't figure out is how to pump all the particle positions through the distancebetween node like the samplerInfoNode does. Of course, I believe the mechanic of sampling is different from an array of positions, but still seems like this is the way to take things.

PLEASE HELP MORE :)

[Vushvush]

Another thing I wonder about, is it possible to get worldPosition attributes from the particleSamplerInfoNode, and funnel those into a regular shader, not a software particle shader?

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