How do you use the karma uniform volume material preset?

Forums Technical Discussion How do you use the karma uniform volume material preset?

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evanrudefx: Member; 266 posts; Joined: 2月 2016; オフライン

2024年4月19日 21:39

How do you get this thing working? In what's new in houdini 20 it says there is a preset for rendering constant volumes. It doesn't work for me unless I go inside and change a few things.

Attachments:
help.PNG (104.1 KB)
Animation.gif (4.5 MB)
uvolume.hiplc (730.3 KB)

Thanks,

Evan


evanrudefx: Member; 266 posts; Joined: 2月 2016; オフライン

2024年9月20日 13:35

Still wondering about this : )

Thanks,

Evan


ObeidaZakzak: Member; 128 posts; Joined: 12月 2019; オフライン

2024年9月21日 6:46

Hello,

Karma Uniform Volume Material is a preset around Karma Pyro Shader VOP, which expects a volume with fields like density, temperature, flame and scatter.

If you want to render a mesh as a uniform volume, you need to set a Uniform Volume property, either from Karma Material Properties VOP or from a Render Geometry Settings LOP, and use a Karma Volume VOP as a material.

Attachments:
KarmaUniformVolume.hiplc (720.9 KB)

Houdini Pipeline Supervisor @ TAT Studio


evanrudefx: Member; 266 posts; Joined: 2月 2016; オフライン

2024年9月21日 11:34

ObeidaZakzak
Hello,

Karma Uniform Volume Material is a preset around Karma Pyro Shader VOP, which expects a volume with fields like density, temperature, flame and scatter.

If you want to render a mesh as a uniform volume, you need to set a Uniform Volume property, either from Karma Material Properties VOP or from a Render Geometry Settings LOP, and use a Karma Volume VOP as a material.

Did you see the docs I posted? It says its for "rendering uniform constant volumes". Also, the preset automatically sets the uniform volume property. So it was intended for geometry, not volumes.

also did you see how I got the karma pyro shader working with the geo in my video? I just had to change a few things.

The uniform volume preset is a wrapper around the karma volume (which can be used for uniform volumes)

I wonder if this is just a bug?

(thanks for the reply)

Edited by evanrudefx - 2024年9月21日 11:45:59

Attachments:
preset.PNG (75.5 KB)

Thanks,

Evan


freshbaked: Member; 153 posts; Joined: 6月 2020; オフライン

2024年9月21日 12:02

Add a density attribute/value to your geo and it will work fine.


evanrudefx: Member; 266 posts; Joined: 2月 2016; オフライン

2024年9月21日 12:08

freshbaked
Add a density attribute/value to your geo and it will work fine.

Thanks! That was it. Unfortunately it only seems to work with cpu (not xpu). But at least its working now. Thanks again.

Edited by evanrudefx - 2024年9月21日 12:08:40

Thanks,

Evan


freshbaked: Member; 153 posts; Joined: 6月 2020; オフライン

2024年9月21日 12:16

evanrudefx
only seems to work with cpu (not xpu)

According to the docs XPU supports "Uniform Volumes" but only the Karma Volume VOP works currently.


evanrudefx: Member; 266 posts; Joined: 2月 2016; オフライン

2024年9月21日 12:23

Thanks again!

Thanks,

Evan


nicholasralabate: Member; 162 posts; Joined: 9月 2017; オフライン

2025年5月16日 12:27

Quick question -- how did you guys add the density attribute? I am trying the same approach and placing a density attrib on my geo doesn't seem to be changing the uniform volume density.

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