smoke color/opacity on very fast sim

[Chris Pember]

ok, here's the situation...

I'm doing a sim that emits fume from an object, the smoke being driven by a wind SW with a strength of about 500. I'm doing this to sim something moving very fast without having gigantic sim bounds.

what I'd *like* to do is the opacity by age, or even the color by age.. which I cant seem to do at all. I've tried everything from grad ramps to, well, pretty much every map I can get a ramp off of The sim itself, if you used particles, would have a particle life of maybe 3 frames

I'd love to know how to use the fluid mapping with a gradient, because it doesnt seem to work at all...What'd be cool as well is to have color/opacity based of distance to object(user picks object, like in the object mode in falloff map)

if you want to repro this scene, make a 30x30x30unit fume box, stick a simple source in it, add a wind with 500 strength, and sim. now try to put a gradient for opacity on it

tks!

cp

[Jordan]

Well, it dosent really make sense for fumeFX to have an age property, as the smoke just moves values from voxel to voxel, and if two different age smoke mixes in one voxel, how are you supposed to get an age value from it. (thats what makes sense to me anyway!)
You can make the smoke fade quicker by increasing the dissapation and min density to your needs.
Or you could use the FumeFX sim as a force in a pflow system then use particle age to do what you need, but then you would be rendering the particles. Even Krakatoa would be able to do this and have opacity by particle age or just a random particle life

[Chris Pember]

Hey Jordan,

Yeah, I've tried all the above (dissipation and min density, etc) I was just trying to avoid having to deal with pflow and was hoping i could do one sim for all my shots I know krakatoa will do the same thing as a fume cache, but it's also resolution dependent, so gets tricky when it gets close to camera, etc. This was also the reason behind my asking about gradient ramps and such, as i could just use that on the fume results (I can sort of do this with a linear map, but it's locked to world space and doesn't move with the object)

tks!

cp