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sample velocity in dops

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I have a custom velocity field that i created in sops and i want to sample it in a particle simulation.

I know that i can easily use the pop advect node but i want to learn how to use the "volumesamplev" vex function for this. It seems like i have everything in order but the particles are not moving.

I think i need a little guidance on this...i will attach my scene file for anyone that wants to take a look.

thank you!

volumesample v.hipnc

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your wrangle is good, but your volume doesn't contain any values at locations of the particles

- in VDB From Particles values are populated only within narrow band around the particle's surface 
in this case it doesn't reach all the way to where particle centers  are so they will not be affected by advection

- you can increase narrow band to fill in the whole particle, but that will also expand by the same distance
and for bigger particles you may still get hollow interior
there is no Fill Interior for VDB from particles unfortunately

- you can also make your particles smaller to get a good ratio between particle scale and narrow band to cover desired area

- or use Attribute Rasterize to get fully filled particle within its pscale with your values, even though it may not end up exactly spherical



Edited by anim
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