Cat Harris
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Recent Forum Posts
Adding AOVs to existing mtlx shaders Jan. 15, 2026, 11:29 a.m.
Thanks for the reply!
Sadly we're usually bringing in the mtlx shaders from outside so rebuilding them from scratch in the Karma builder isn't really an option. It looks like for now I'll have to just suck it up and render the original shader and the custom Karma AOV shaders as separate images, and then glue them together into one exr afterwards in COPs.
It's good to get confirmation that I shouldn't spend too much more time down this particular rabbithole, and at least with Houdini there's always a solution, even if it's a bit ugly!
Sadly we're usually bringing in the mtlx shaders from outside so rebuilding them from scratch in the Karma builder isn't really an option. It looks like for now I'll have to just suck it up and render the original shader and the custom Karma AOV shaders as separate images, and then glue them together into one exr afterwards in COPs.
It's good to get confirmation that I shouldn't spend too much more time down this particular rabbithole, and at least with Houdini there's always a solution, even if it's a bit ugly!
Adding AOVs to existing mtlx shaders Jan. 12, 2026, 10:55 a.m.
Hi all, I'm trying to work out if it's possible to take geo with existing shaders and then add additional aov shader passes without having to do multiple renders. For workflow reasons we'd really like to just have one exr output with beauty and all AOVs included.
simple example - I'd like to take an prebuilt usd asset and render it with both its original correct shaders (beauty, reflections etc.) and also add a custom uvmap pass.
Things I've already tried:
Hopefully someone's already had a play with this and has a solution, if not I'd love to know if anyone has any more ideas I can try!
simple example - I'd like to take an prebuilt usd asset and render it with both its original correct shaders (beauty, reflections etc.) and also add a custom uvmap pass.
Things I've already tried:
- Creating the custom aov shader separately in the material library - works fine if I'm happy to render this separately but I can't find a way to switch between the beauty and aov shaders within the same render
- Doing everything with primvars - works fine for attrib based AOVs, but some things eg. texture maps only work if I go via a shader.
- Using an edit material to add the map and a Karma AOV to a shader, then outputting everything either as binds or using the Subnet Outputs node - this seems to add the attribs to the material prim that I'd expect, but still renders black even when the made-from-scratch AOV shader is working on other geo.
- Trying to do it in python - I'm not sure what I'm missing in terms of USD structure and changes to the mtlx shader prims to make this all work, so this ran aground pretty quickly in the API docs!
Hopefully someone's already had a play with this and has a solution, if not I'd love to know if anyone has any more ideas I can try!
HDK problem - error running hcustom on example file on OS X April 13, 2016, 7:41 p.m.
Hi, I'm having a go at working with the HDK, but I can't get the geoisosurface.C file to compile properly as explained in the introduction documentation.
When I run hcustom -s geoisosurface.C
The geoisosurface.o file seems to be generated correctly, but then I get the error
ld: file not found: @rpath/libHoudiniAPPS3.dylib for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Link failed
The clang command that's being run (found via running hcustom with -se flags) is
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ geoisosurface.o -o ./geoisosurface -Wl,-rpath,/Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries -L/Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries /Library/Frameworks/Houdini.framework/Versions/15.0.416/Houdini -arch x86_64 -fobjc-gc -framework OpenGL -framework Cocoa
I've checked and the file libHoudiniAPPS3.dylib does exist in /Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries.
I'm running El Capitan 10.11.4 and have the latest version of Xcode (v7.3), and have a clean install of Houdini v15.0.416.
Sadly I've now reached my limit of debugging skills, so is there anyone who knows what's up here? Have I just not set something up correctly, or should I submit a bug to SESI?
When I run hcustom -s geoisosurface.C
The geoisosurface.o file seems to be generated correctly, but then I get the error
ld: file not found: @rpath/libHoudiniAPPS3.dylib for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Link failed
The clang command that's being run (found via running hcustom with -se flags) is
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ geoisosurface.o -o ./geoisosurface -Wl,-rpath,/Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries -L/Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries /Library/Frameworks/Houdini.framework/Versions/15.0.416/Houdini -arch x86_64 -fobjc-gc -framework OpenGL -framework Cocoa
I've checked and the file libHoudiniAPPS3.dylib does exist in /Library/Frameworks/Houdini.framework/Versions/15.0.416/Libraries.
I'm running El Capitan 10.11.4 and have the latest version of Xcode (v7.3), and have a clean install of Houdini v15.0.416.
Sadly I've now reached my limit of debugging skills, so is there anyone who knows what's up here? Have I just not set something up correctly, or should I submit a bug to SESI?