Forums Technical Discussion Gradient Fall-off Volume

Gradient Fall-off Volume

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Tanner Chow
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Hi everyone, I am dabbling with volumes recently and I wish to know how can I have a fall-off of volume, gradiently? (see image attached).

I have zero to minimal knowledge of volume vop. Forum Users talk about volume sample and volume gradient when I search on forums regarding this issue.



**Additional Info– Better still if I can control, say, point A is densest and point B is thinnest.**



Thank you in advance.

Attachments:
grad.jpg (970.3 KB)

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mestela
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Something like this?

Attachments:
vol_spherical_density.hip (72.4 KB)

http://www.tokeru.com/cgwiki [www.tokeru.com]
https://www.patreon.com/mattestela [www.patreon.com]
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Tanner Chow
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Wow, this is it. It's very nice. Thank you! Really appreciate it.
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Alexandre Dizeux
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Super cool ! this exactly what I was looking for ! thanks thanks thanks !
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buzzdev
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Hi there,
i am completely new to Houdini, sorry for that.
How would i create volumetric gradient, that is more dense at the bottom and density will be less at the top?
A volumetric vertical gradient i mean.
Many thanxs for help
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animatrix_
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Inside a volumewrangle you can just do:

@density = 1 - relbbox(@P).y;
Senior FX TD @ Industrial Light & Magic
Get to the NEXT level in Houdini & VEX with Pragmatic VEX! [www.pragmatic-vfx.com] https://lnk.bio/animatrix [lnk.bio]
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tapoh
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animatrix_
Inside a volumewrangle you can just do:

@density = 1 - relbbox(@P).y;
thanks! and how this can be achieved along all three axes x,y,z?
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jpparkeramnh
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tapoh
thanks! and how this can be achieved along all three axes x,y,z?

Without testing, probably like:
@density = 1 - length(relbbox(@P));
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Kareeem
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jpparkeramnh
@density = 1 - length(relbbox(@P));

Unfortunately this doe not work. Has somebody a solution for this?
www.rehimi.de
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Kareeem
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mestela
Something like this?

this works though.
www.rehimi.de
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animatrix_
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If you want to have falloff for 3 axes, you can do something like this in a Volume Wrangle SOP:

vector r = relbbox ( @P );
@density = ( 4 * r.x * ( 1 - r.x ) + 4 * r.y * ( 1 - r.y ) + 4 * r.z * ( 1 - r.z ) ) / 3;

Attachments:
x.png (880.0 KB)

Senior FX TD @ Industrial Light & Magic
Get to the NEXT level in Houdini & VEX with Pragmatic VEX! [www.pragmatic-vfx.com] https://lnk.bio/animatrix [lnk.bio]
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