Hi
We have some issues when we are try to make a multi render material library thru solaris/usd and all is kicking well except when working with the vray version in houdini. We can´t by any means handle a vector4 data type inside the vex builder with only vray nodes. the docs says there should be a vector to color operation Texture Utility - V-Ray for Houdini - Chaos Help but this is missing in the vray plugin.
All the best :)