Hello

I have little problems with my volcano smoke. First problem with shader, I use my shader, created from miguel, an try some shader from OD force comunity, but there is some mistake.
Another problem is with sprites,
1, rotation, I need rand rotation on begining and from fast to zero rotation speed based on lifespan. I found some expressions but not exactly what I want.Maybe ramp in sprite user interface with start rotation…
2, scale. It is possible connect this parameter to ramp base on lifespane, based on lifespan? something like in maya. Just ramp for lifespan with min max parameter like ramp array mapper for start and and size od sprite. I mean add ramp to sprite interface forexample and connect it, without another colour parameter.

I attaching file, please look at it someone, really I need it.

Thanks a lot BC

Hello
I try everything, but I can't still see sprite particles with shader, sprite node gives an error “ smoke sprite1 does't export openGL material ” where is the problem? Thanks a lot for help…BC….

Hello

I search, try examples and there is my result. But still have some problems.

Rotation: there is some strange things, particles starting rotate fast at the end of lifespane. I' m not good at the expressions, but I need something like this. I' l write it like in maya

Creation expression (for begining of birth), random rotation 360 degrees , runtime expression +/- rotation + same rotation
How could I write it in houdini?

Scale:

Creation expression: random scale (1, 10) , rutime expression $LIFE + 10

Another problem is with rendering, If I have cca 7 000,- particles, looong time evaluating script, then open Mplay and render is fast, where is problem?it is problem with calculating deep shadows? There is a attached file.

Thanks a lot for your support, it is difficult for me to switch from maya, thanks.

try this expression in the Rotate field

fit01(rand($ID),-1,1)*fit01($LIFE,-1,1)*360

this expression allow a random rotate at the initial frame per particle, and a correct rotation rate based on the lifespan per particle.

Thanks a lot alejandro. I'll try it.