functionality to deform volumes

[johnnyquest]

https://www.facebook.com/qLibHoudini/photos/a.396009720432818.98425.145692112131248/1162383330462116/?type=3&theater

• this could work both for volumes and regular geometry
• i thought there's a ticket for this already?!?!?!?!
• important note: the rest tetmesh should always fully cover the entire volume + some margin

some code!

int prim;
vector uv, p0;

xyzdist(chs('deformgeo'), @P, prim, uv, 0.0001);

if (prim>=0) {
p0 = primuv(chs('restgeo'), 'P', prim, uv);
@density = volumesample(0, 0, p0);
} else @density=0;

limiting the xyzdist() lookup and using the if() is way faster than just blindly looping through the volume

should work with vector (velocity) fields

put an additional vdbactive at the end to get rid of empty areas

duplicate of #408

[johnnyquest]

geometry:

• publish tolerance, attrib interpolate attrib list, etc
• two-phase mode: generate prim/primuv, do interpolation (both phases switchable)

[johnnyquest]

first prototype done, so i'm closing this