Color smoke with a ramp

[chica]

Hello,

I want to color a smoke volume with a ramp. The way i want the ramp to appear is based to the time the smoke exists in the scene. To make it more clear, I want to do something similar like in particles, where you would color them based on the $LIFE attribute. I am using the billowy smoke shader.

sub-question: how can u use displacement for the billowy smoke?

Thanks a lot in advance.

[ikarus]

Hello,

I want to color a smoke volume with a ramp. The way i want the ramp to appear is based to the time the smoke exists in the scene. To make it more clear, I want to do something similar like in particles, where you would color them based on the $LIFE attribute. I am using the billowy smoke shader.

sub-question: how can u use displacement for the billowy smoke?

Thanks a lot in advance.

the voxel data in a smoke object always exists (or atleast from the creation frame). The grid values are just at zero if they are "empty" in terms of density. If you wanted the effect of smoke changing color based on "life" you would have to base the smoke from particles, create a custom "color" field for the smoke object that is fed "life" or "color" from the particle system, which could be read by a volume shader, which in this case why wouldn't u just use particles instead?

http://www.peterclaes.be/tutorials/PeterClaesThesis/index.html -peter claes' thesis on custom fields would be a good source of info though for coloring smoke.

-billowy smoke is coded as a "volume" shader. volumes dont have surfaces and therefore, dont have a surface to be "displaced", you can vary the density with noise or other parameters in the shader though

[chica]

Thanks a lot for the reply. In fact I am using a particle system to drive the smoke simulation with using point velocity. I still haven't managed to transfer the color to the volume. What is the process at the sop level to transfer the cd attributes from particles to the volume? Any chance of any example files?

[Ratman]

Bump, running into a situation like this right now, and pretty much coming up blank.

[ikarus]

What you essentially need is a vector field named Cd that you would just use a volume VOP to copy the color of your particles to the field via a pcopen/pcfilter, and making sure the field is the same size as your other fields.

should be that simple, I think?