Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] General Discussion => Topic started by: davetwo on 2022-09-11, 11:56:44

Title: Decals can't be transparent?
Post by: davetwo on 2022-09-11, 11:56:44

Hi all. I am trying to make a wet streak run across 3 different floor surfaces. I thought that using decals would be a perfect solution as it would run across all 3 objects and pick up the underlying dispacement - but unfortunately I cant get the decal to be transparent. Its always opaque white even if I have refraction turned on. Thin shell and changing the base colour make no difference. Is this a bug, or a limitation, or am I just doing something wrong?

Title: Re: Decals can't be transparent?
Post by: Beanzvision on 2022-09-12, 09:56:08

Hi there,

Have you tried lowering the opacity amount? Seems to work here. ;)

(https://forum.corona-renderer.com/index.php?action=dlattach;topic=37842.0;attach=171173;image)

Title: Re: Decals can't be transparent?
Post by: Juraj on 2022-09-12, 10:16:44

They can be 'transparent' (opacity), but they can't be 'refractive' in true sense.

That's because Decal is just automatic LayeredMaterial, which isn't physically "layering" anything at all (like real water on top of dry ground), it's just mixing two materials in different ratio, like Photoshop layers..
So certain hacks which look similar must be employed but it will never simulate actual multi-layered mesh behavior.

Title: Re: Decals can't be transparent?
Post by: davetwo on 2022-09-12, 13:42:19

Ah interesting. So a decal with clear areas (like my attached mock-up) is not possible.
Shame - all the other ways are a little more convoluted. Thanks for the replies.

Title: Re: Decals can't be transparent?
Post by: Juraj on 2022-09-12, 15:59:12

Well it is, but not in that logical sense of way that emulates real world :- ). Your example should work with partial opacity (perhaps with fallof for fresnel).