Corona Proxy gets materials wrong

[lollolo]

I'm having an issue with Proxy.

- Create a cube
- make several poly selections
- apply a material to every selection
- create a Proxy - until now everything is working
- create another material and apply it to one of the selections you created before (so a selection is used twice)
- create a proxy - materials are not correctly applied.

In my example here, only one material channel was created, but there should be 6.

Win 10
C4D R20 + 12 hotfix 2

Can you reproduce it? Thanks for checking.

[lollolo]

Were you able to reproduce this issue?

Thanks

[maru]

I can reproduce it in your scene, but not in a new scene (C4D 2025, Corona 12 U1 HF1). For some reason your cube exports as a proxy with 1 material channel. If I do it from scratch, I end up with 3 channels (when using 3 materials).

Could you explain how you are doing this from scratch, step by step? Or maybe record a short video, if I'm not asking for too much.

[lollolo]

@maru thank you for your reply. I sent you a PM with a link, because Corona uploader doesn't work for me.

It does still happen to me, even when I create a new scene. I'm using R20 and Corona 12 Update Hotfix 1. Perhaps it is related to R20 only?

[bnji]

Hello there @lollolo,
When manually creating a proxy, please make sure to use texture map files for the applied materials.
I can see from your scene project you're using a procedural checkerboard texture. (this is why it only creates a single material channel)
Using texture map files for the materials will create the appropriate number of material channels for the proxy. (see attached image)
Note: Also, do not forget to create the UVW coordinates for each material. (select the material tags > right-click on any of them > "Generate UVW Coordinates")
This way, you can even load the exported ".cgeo" file in 3ds Max using the Corona Proxy object. (just need to recreate the same materials)
I hope this helps.
Looking forward to hearing from you.
Kind regards.

[lollolo]

@bnji thanks for your reply.

It looks like your example is not corresponding to my example. I can also have 3 or more poly selections and materials assigned. Works fine. The problem starts, when I add a second material to one of the selection.
An example in a real scene could be a base material and then a dirt or snow material on top with opacity channel activated. In this case you would use a poly selection twice.
Tree as example:
poly selection 1 - trunk
poly selection 2 - branch
poly selection 3 - leaves (until here everything is working)
poly selection 3 - snow on leaves (and this is where the issue begins, a selection is used twice)

Workaround for now is to use a layered material, so I don't have to use the poly selection twice.

As I wrote:

- Create a cube
- make several poly selections
- apply a material to every selection
- create a Proxy - until now everything is working
- create another material and apply it to one of the selections you created before (so a selection is used twice)
- create a proxy - materials are not correctly applied.

Does it work for you if you assign a second material to an already used poly selection?

[bnji]

Hello @lollolo,


Thank you for your feedback.
I can confirm the 4th material that is reusing the polygon selection is not generating an additional material channel for the proxy.
Sticking to the example you provided, some users solved similar issues by using layered material instead, as you mentioned.
Perhaps you may want to log your feature request on our Ideas Portal: https://chaoscorona.ideas.aha.io/
You will need to pick "Add a new idea" and describe your feature request in detail.
For more information, please see:
Corona for Cinema 4D - https://forum.corona-renderer.com/index.php?topic=43390.0