Alpha cutouts: how to turn these on?

[model-raise]

Try loading my USD test file McUsd.usdz found in https://github.com/usd-wg/assets/tree/main/full_assets/McUsd into C4D (2024.2.0) by dragging and dropping it into the viewport. Set the camera by selecting its "box" in the upper right (see screenshot).

The sunflower object in the foreground should be a cutout object. Instead it has some semitransparent shading, as if it's using some other channel than the alpha channel for transparency. Examining the material, I don't see a way to make the shader use the alpha channel.

For comparison I've attached what I see in UsdView, which is correct.

C4D used to import (an earlier version) of this scene just fine, see https://github.com/erich666/McUsd?tab=readme-ov-file#cinema-4d. I have also tried exporting to OBJ and get the same sort of semitransparent problem.

[Dr. Sassi]

Hi model-raise,

Please look here; that would be a way to get PNG somewhere. To make this information available, a Color Splitter is needed.

If you want to see more about what works and what doesn't, set up a scene and export it to USD. Then, import it and compare the result with the Source scene.
Perhaps open a ticket with anything that isn't working.
https://www.maxon.net/en/support-center

All the best

[model-raise]

Thanks for the fast response. I expect I could figure out the shader graph and how to add alpha transparency manually. I was mostly asking if there was some option I was missing for USD import so that the USD file would display properly when read into Cinema 4D. It sounds like there is not, so this seems to be a regression - C4D used to read in this type of USD file and display it with cutouts. So, as you advise, I've reported this as a bug (well, a "suggestion" - there doesn't seem to be a way to report a bug?): https://support.maxon.net/hc/en-us/requests/657464

I hope it's a help. I love C4D's intuitive nature (I'm testing as part of my work at NVIDIA), sorry to see this part of the USD importer no longer work correctly.

[Dr. Sassi]

Thanks for doing that, model-raise!

You're spot on to ask; I certainly understand and support this.

There is an entry for Tech-Support in the upper right corner.

My personal take on this is:
I haven't paid a lot of attention to USD and materials. The simple reason is that the translation of materials and color is all over the place, considering the vast amount of material systems on the market alone from 3rd party rendering engines. Yes, the idea that all fits through the definitions of the USD system.
But even that simple opacity problem requires some work. I often have my materials based on MoGraph, for example. That is, as far as I know, not an option. Even though I do not expect to have the MG set up arriving, the colors are gone. So, more work is needed regarding USD definitions and options.
Or take the Maxon Noises, animated perhaps; I haven't seen an option.
I need to dive deeper into it, no question. I believe it will get better.

Cheers