emitting particles from color

[Omy]

I have red color in the geo and i want to birth the particles from red color/how this could be done.thanks

[kare]

create group for your red colour geometry(for eg: $CR>0.9&&$CG<0.6)

and add that group in your source particles...

[Netvudu]

Another fun and simple way.

Use $CR as your Birth Probability on the Source POP.

If you want to see it clearer use something like $CR^3

Check the attached scene.

ParticlesBornFromColor.hipnc

[Macha]

Turn $CR into a prim attribute and rename to area. Then emit by area or scatter by area.

Or,

Scatter colored points and delete with an expression like rand($PT)*$CR>0.5, then emit from those.

[tjeeds]

I didn't know this until recently but the Scatter SOP accepts Cd directly, it's only the Source POP that requires a primitive float. So you can plug into a scatter and use those points as emitters.

Edited May 24, 2012 by tjeeds