I'm having problems getting materials to work in LOPS. I put down a material library after a SOP Import and within the material library I have a principal shader although when I click auto-fill materials; I get a dialog asking for the Material Network Path and the USD Path Prefix ?

For the Material Network, I have the name of the shader; in this case, principal shader. And the USD Path Prefix I have the root of the hierarchy which is, /set.

As for the Material VOP, I have; /set/pig the Geometry Path is; /set/pig and the Material VOP is; Principal Shader but when viewing the object in LOPS whether OpenGL or Karma, there is no change ?

If you are using auto-fill button, it may be useful to click "clear" button next to "number of materials". Otherwise, the LOP may not fill out some VOPs that are already covered by globbing in the existing entries.

But you should not need the auto-fill. The principled shader vop will be picked up by the globbing asterisk.

You can also try Assign Mateial LOP to bind the materials.

I found the problem, Assign to Geometry was toggled on; but, I had to set the Geometry Path to; Parent of Input last modified primitive or the expression; `lopparentprims(lopinputprims('.', 0))`. Unless there is another way ?