Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: Psifinity on 2022-07-09, 21:50:34

Title: CoronaVolumeMtl: Transparency Issue
Post by: Psifinity on 2022-07-09, 21:50:34
(This is on 3ds Max 2023 with Corona 8.2)

I'm using a cylinder with a volume material to act as a "container" of sorts for some noise clouds.
At first when I ran into a transparency problem involving the cylinder geometry itself appearing as a silhouette in the render, I did the EnviroDistance fix as listed here (https://support.chaos.com/hc/en-us/articles/4528311915025-Known-bugs-and-limitations) to workaround the problem; iirc it was 1000cm prior, so I set it to 500,000cm after several adjustments.
 
It seems to have mostly solved the issue in terms of the BEAUTY & CESSENTIAL_Volumetrics render elements, however the Alpha render element itself still shows that it remains to be an issue.
Here's the scene & images pertaining to said render elements.
Title: Re: CoronaVolumeMtl: Transparency Issue
Post by: maru on 2023-06-26, 10:25:39
Sorry for the lack of updates here!
It's been a while, but this is finally fixed in Corona 10 as "User can now set how volume (volume material, sky volume effect and volume grid) interact with alpha channel. + Semi-transparent volumetric effects now also contribute to alpha channel for rays not hitting anything" - https://blog.corona-renderer.com/chaos-corona-10-released/

If you open this scene in Corona 10 now, you need to change the alpha mode of the sky's volume effect to "always black" (otherwise it will appear as white in the alpha channel) and then it will render as expected.
Additionally, you can specify how alpha should be handled for the Volume Mtl.