Using a primvar string to give a texture path

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brians
That is some good investigating
Thanks!

brians
Unfortunately, we have not had a chance to get this feature into H20.5 as we hoped. But it is a high priority for us, so we're at least aiming for the next release.
Good to know that the main hurdle has been solved! I'll keep my finger crossed for Houdini 21 then.
Edited by PaoloGiandoso - July 16, 2024 20:46:22
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Unfortunately, we have not had a chance to get this feature into H20.5 as we hoped. But it is a high priority for us, so we're at least aiming for the next release.

I just saw the Houdini 21 preview. Am I correct in my understanding that primvar texture strings will be fully supported by Karma GPU in Houdini 21? 🔥
Edited by PaoloGiandoso - Aug. 7, 2025 16:25:06
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I just saw the Houdini 21 preview. Am I correct in my understanding that primvar texture strings will be fully supported by Karma GPU in Houdini 21? 🔥

You are! From the feature list [www.sidefx.com]:

XPU: Support for string primvars
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PaoloGiandoso
I just saw the Houdini 21 preview. Am I correct in my understanding that primvar texture strings will be fully supported by Karma GPU in Houdini 21? 🔥

You are! From the feature list [www.sidefx.com]:

XPU: Support for string primvars
Oh unbridled joy!
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In keynote discussion somebody from sidefx team told me that string primvars for textures would also work for vulkan

I can't seem to make it work (i've tried asset and string primvars with any interpolation). It just ignored for realtime shaders
Does anybody manage to make it work for realtime viewport or it's just not supported?
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it Works withg the mtlxUsdPrimvar reader .

not with the usdprimvarreader.
Edited by NicTanghe - Sept. 13, 2025 08:53:56
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hm, not sure what i'm doing wrong
my simple example attached just not working

I also tried Geometry Property Uniform Value which probably could have better semantics for realtime but still no luck (not working with Mtlx Usd Primvar Reader either)

I tried several approaches to set primvar just in case but it seems unnecessary, i was just unsure if something wrong with Edit Properties LOP for example (like if it's ok to just put property in UI to primvars: namespace)
Edited by elovikov - Sept. 13, 2025 14:56:23

Attachments:
mtlx-test.hip (140.9 KB)

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Here is an example. mtlxgeompropvalueuniform will read file primvars. You don't want to use strings, as asset path primvars get resolved, and is what you should be using for file paths. Also the primvars need to be constant (i.e. a single-value for the prim). You can't interpolate strings across faces or points. On PointInstancers, those primvars are technically vertex-interpolated, but they still follow the same rule, as each instance gets only 1 value.

The helpcard for mtlxgeompropvalueuniform [www.sidefx.com] was messed up. It will be correct when the online docs are updated tomorrow, after with tomorrow's build.

Hope this helps!

Attachments:
Screenshot 2025-09-13 153058.png (420.3 KB)
constant_primvar_texturemaps.hip (222.2 KB)

I'm o.d.d.
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Thanks!
sorry, I think I wasnt very clear
I don't have any problems with cpu and xpu and it's working great (though thanks for clarification)

it's just I was told in H21 keynote chat that it's also supported for Vulkan, that was my question if it's supported there
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