UsdPreviewSurface opacity result unexpected when connected to an image

[drwave]

Using latest dev branch, I'm seeing an issue with transparency in UsdPreviewSurface that seems new.

I have 4 meshes, each with a simple material mapping a texture image on them:

• set opacity to 1
• wire opacity to the a of the RGB JPG file (I expect it to be the same as 1)
• for two, wire opacity to the a of the RGBA PNG file

For the PNG meshes, I expect them to be transparent around some parts, and completely opaque in other. Unfortunately, you can see through all of it.

See the enclosed USDZ file, and then an image showing the expected value and then a linux version in usdview showing the problem.

AlphaTest3.usdz.zip

[jilliene]

Filed as internal issue #USD-6372