hello forum,
this is my first post, i just started testing two days ago - so i am a stoke newbie.
is there any kind of functionality like interactively setting fields into the voxel grid? like “paint” velocity or density fields for example?
thank you,
fuat
That is on the ToDo list of Ember, but is not currently on the Stoke list.
Stoke is meant to use existing sources (force fields, particle systems, FumeFX and Ember) to advect particles.
You can do a lot of things using the Krakatoa PRT objects though. For example you could create Max Hair and comb it to define a field, then convert to PRT Hair and set the Tangents as Velocities… I remember playing with that by creating a grid of planes and growing hair on them, then using the paining tools to tweak the velocities. 
Or you could just draw a bunch of splines, turn them to PRT Hair and again use the Tangents. You would not be able to paint, but you could adjust the force lines respectively. Tom Hudson is also working on a Force SpaceWarp to use splines as guides, so that might come in handy if/when released.
An even more indirect way would be to create a simple Spray particle system and use splines and Path Follow SpaceWarp to guide the particles along the spline. Then use that as Velocity source in Stoke.
Finally, since both Stoke and Krakatoa are widely open to MAXScript, it would be also relatively easy to write custom tools to produce velocity fields.
wow. that sounds very interesting. didn´t know that.
thanks for your explanation, Bob.
cheers
Fuat