Simon Ohler

Using the materialvariation node set to point instances and the instances parameter to something like /myinstancerprim1[*], you could create a new primvar based on the index variable:
toggle use snippet and set the wrangle to:
value=index

.. which will give you the instanceid as a primvar, so it can be read in your material.

Though probably better for material variation would be to create a color3f primvar already with the desired variation color and just read that directly in your material.

To read primvars in Karma, you can just use a parameter node.

Look into hou.contextOptionConfig() ..on how to format the ui configuration and hou.setContextOptionConfig() to actually apply it.

To be able to set the setContextOptionConfig, you first need to create the context option itself (for example via hou.setContextOption("shot", "somevalue"))

..currently usdview seems to be the best place for getting that information:

https://github.com/ColinKennedy/USD-Cookbook/tree/master/references/usdview_style_documentation [github.com]

usdview: $HFS/bin/usdview