Volume density based on point position and/or depth

[TheDude123]

Hi,

I'm trying to figure out how to decrease a volume's density based on some value (say a point's position in space).

Say you have a sphere converted into a volume and a point at the center of that volume.

How do you go about calculating the volume's distance from that point and modifying the density based on that?

I would like the density to decrease the closer it is to the point.

I've tried volumesample(), volume gradient VOP node, and a few others...but I'm missing something.

Either VEX or VOP solution is fine.

Density decreases closer to the center...

Thanks!

Edited May 20, 2022 by TheDude123

[Librarian]

link

linkk

maybe it helps

[TheDude123]

Thanks for the links. After some testing, they work, but the falloff created is not linear (for the shape I'm using).

I would like the density to be highest on the outside of the box shape and fade towards the "center". What I'm currently getting is: dense, less dense, than dense again (see image). RED text from 0-1 is what I would like.

See .hip file and image below.

Thanks.

density_box_fade.hiplc

Edited May 20, 2022 by TheDude123

[Atom]

Maybe check out the volumefeather node..?

[doc]

Very close to getting it working, but in my test I'm getting a weird wedge of high density. Maybe somebody smarter can tell me what I missed?

volume_fall_off_test_v1.hip

[konstantin magnus]

You could remap a signed-distance field.

f@density = fit(f@density, 0.0, -0.2, 0.0, 1.0);
f@density = chramp('density', f@density);

volume_fall_off_test_km.hipnc

[Librarian]

@doc hm
exact what i need ...but how to solve that wedge hm ..endless sacred patterns Thanx

Edited May 21, 2022 by Librarian

[doc]

I noticed that increasing the resolution of the sphere seems to make the problem go away, but I'm not sure why that would make a difference

Edited May 21, 2022 by doc

[Aizatulin]

Hi doc,

in your wrangle write test >= 0, because 0 is also a valid primitive number.