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RPR v2.0.32 Uber Shader - Material Assignment *for stickers* - transparency ignored on material assigned faces

I'm trying to achieve a simple effect where an image map is used as a sticker on an object.

I was using the Uber Shader Glass material setting but because that introduces other issues I have also tested it on a Uber Shader Metallic material as well. The problem is even more apparent on metallic or diffuse objects.

I particularly want the background area of the assigned material zone to disappear so that the image appears to be printed onto the surface. The material of the sticker can be anything (e.g. an emission) but for this test simple diffuse materials were used.

I have included a test file. Embedded within the test file are four variants of each of the Logo image maps. These include black and white, white and black, black and transparent and white and transparent versions. Only the non transparent PNGs (those with solid black and solid white) have any effect.

The area around the image is UV mapped and scaled appropriately around the sticker image and the material slot for the image is assigned to this area. An Uber shader is then used to setup the material for the sticker and use of the transparent node map to mask out the background area (this is where it doesn't render correctly).

The problem is that the whole area where the sticker material is assigned renders black on diffuse or metallic objects and has an even odder effect on other materials such as glass.

Please see the renders below and the included test files.

RPR version 2.0.32. Blender 2.8.53 macOS.

GPU used: Radeon Pro 560 4GB on MBP 2017. (no eGPU used).



Please see file "Shader Ball v22-6 B280 Glass on Glass with LOGO ProRender Uber Mix.blend" for the problem.

It only occurs with Glass on Glass. The metal on metal Logo on the lower section of the image renders correctly.

I also include the version done with Principled shader and the Mix node which renders fine.


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