Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => Topic started by: fobus on 2022-04-16, 06:31:49

Title: Cast shadows override not working
Post by: fobus on 2022-04-16, 06:31:49
There is a bug in Corona 8 with "Cast shadows" parameter in object properties. Unchecking it with map in diffuse can't switch off shadows completely.
Title: Re: Cast shadows override not working
Post by: fobus on 2022-04-20, 11:27:46
Will it be fixed or we have to switch back to Corona 7?
Title: Re: Cast shadows override not working
Post by: GeorgeK on 2022-04-20, 12:02:41
There is a bug in Corona 8 with "Cast shadows" parameter in object properties. Unchecking it with map in diffuse can't switch off shadows completely.

Hi,I am afraid this is known bug/limitation https://support.chaos.com/hc/en-us/articles/4528311915025-Known-bugs-and-limitations, please note that CoronaPhysical Mtl has reflectivity enabled by default and that's why the issue becomes more apparent in your case, you can either use CoronaLegacy Mtl with no reflections. Or, with CoronaPhysical, to remove reflectivity to an extent you will have to make your IOR value 1.0 and Roughness 0.0 (at 1.0 it might be still visible).
Title: Re: Cast shadows override not working
Post by: fobus on 2022-04-20, 12:45:30
Why there was no such thing in the same scene in Corona 7 than? I have no problems with it in 7. Something has been changed in 8, is't it?
Title: Re: Cast shadows override not working
Post by: GeorgeK on 2022-04-20, 13:02:22
Why there was no such thing in the same scene in Corona 7 than? I have no problems with it in 7. Something has been changed in 8, is't it?

Hi again, it's exactly the same case with Corona v.7, the biggest difference is between CoronaPhysical and CoronaLegacy Mtl, the issue as previously explained is that it's more apparent with the physical model due to roughness and by-default enabled reflection.
Title: Re: Cast shadows override not working
Post by: maru on 2022-04-20, 13:08:41
This scene seems to render the same for me in V7 and V8.
Do you have an "open and render" scene which we can test in V7 and V8 to see the difference?
Title: Re: Cast shadows override not working
Post by: fobus on 2022-04-20, 15:03:34
I have scene from 7 with no artefacts in it. Opening it in 8 caused me to be worried about this.

Same scene, same setup, different Corona versions. So much different results! Scary...
Title: Re: Cast shadows override not working
Post by: maru on 2022-04-20, 17:10:25
I have scene from 7 with no artefacts in it. Opening it in 8 caused me to be worried about this.

Same scene, same setup, different Corona versions. So much different results! Scary...

Link to scenes: https://cloud.mail.ru/public/6Hd6/umc6RteHQ (https://cloud.mail.ru/public/6Hd6/umc6RteHQ)

Are you sure that you can share your scenes publicly?

Here is how your scenes render in Corona 7. The issue is still there, and it is the same as in Corona 8. The results are different because you are using the Corona UVW Randomizer map here, and it has changed between V7 and V8 - this is expected. You are free to go back to Corona 7, but this won't change anything.

As George from our team correctly explained before, this is a known "black highlights" issue which is described here: https://support.chaos.com/hc/en-us/articles/4528311915025-Known-bugs-and-limitations

The solution is to restrain from disabling the "cast shadows" option in object properties.

Also, V-Ray doesn't have this issue.
Title: Re: Cast shadows override not working
Post by: fobus on 2022-04-20, 18:01:15
It was a bit strange to see so much difference as you can see on "pavement" pictures between 7 and 8 Corona versions. Can't accept that the difference between pictures is only by other randomization IDs...
All other versions translations was silky smooth.
Title: Re: Cast shadows override not working
Post by: maru on 2022-04-21, 09:24:33
It was a bit strange to see so much difference as you can see on "pavement" pictures between 7 and 8 Corona versions. Can't accept that the difference between pictures is only by other randomization IDs...
All other versions translations was silky smooth.

In that case I would suggest staying with Corona 7 until you finish the project and switching to V8 only when working on new projects. This is generally a good practice.
In many previous releases we've had similar issues. We try to keep consistency, but can never guarantee 100% identical results when upgrading to the newest version. This is simply impossible, especially with so many changes and new features in V8.

Sorry about that, and please note that the root issue here ("black highlights") is the same in V8 and older versions.