Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] I need help! => Topic started by: tennet on 2023-08-17, 14:23:37

Title: [solved] Using Opacity mask in labels still cast shadows?
Post by: tennet on 2023-08-17, 14:23:37
Hi,

When I'm using opacity masks in a material to cut-away parts of a product label, then the cut-away parts still cast shadow onto the product behind.. My label renders correct when using the opacity mask, but shouldn't only the visible parts of the label cast shadows/reflection on the surface behind (not the the parts that have been cut-away)?

Any tips or tricks to make this work?
Title: Re: Using Opacity mask in labels still cast shadows?
Post by: romullus on 2023-08-17, 14:47:35
Parts of the mesh that are fully transparent should not cast shadows, nor be visible in reflections/refractions. Can you show problematic render so we can see the issue?
Title: Re: Using Opacity mask in labels still cast shadows?
Post by: bnji on 2023-08-18, 00:55:11
Hi @tennet,
Thank you for contacting us.
Could you please elaborate a bit more about the issue?
Additionally, please provide some screenshots or even screen recordings to illustrate the issue.
Looking forward to hearing from you soon.
Title: Re: Using Opacity mask in labels still cast shadows?
Post by: tennet on 2023-08-18, 14:35:24
Hi,

Thanks for your quick replies! 🙏 I managed to find and solve the problem myself, it was an user-error again.. I had applied the label material (with the opacity mask) only to the "front side" of the label object (only to the "polygon normal side"). Then I used a second WHITE material on the backside of the label, but the white material didn't have the opacity mask loaded... so then I guess the 'white backside material' was still casting shadows/reflections on the object behind the label, even if it was not visible.

When I deleted the white material OR loaded the same opacity mask to the backside material, then the shadows disappeared. Same if I changed so that the label material was applied to "both sides" (see screenshot).

Thanks again, but my mistake!
Title: Re: [solved] Using Opacity mask in labels still cast shadows?
Post by: bnji on 2023-08-22, 18:35:53
Hi @tennet,
Thanks for letting us know.
We're glad you found the root cause and that everything is fine now.
Cheers.