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Chaos Corona for Cinema 4D => [C4D] General Discussion => Topic started by: malindis on 2020-10-21, 11:36:55

Title: Alpha problem with backplate
Post by: malindis on 2020-10-21, 11:36:55

Hello,

I'm on Mac with Corona 6 hot fix 1 and C4D s22.

I have a simple scene with a backplate for the sky (not for lightning the scene but only for visibility). This backplate is assigned with a light material where I put the picture of the sky. This material emits no light (Emit light to OFF) and in the advanced settings I have unchecked the Visible to alpha channel...

Now when I render the images, the backplate is still visible in my alpha !!! why is that ?

Thanks for your help.

Best

stefan

Title: Re: Alpha problem with backplate
Post by: Beanzvision on 2020-10-21, 11:47:59

Hi Stefan,

Can you share your scene with us via our private uploader?
https://corona-renderer.com/upload

Title: Re: Alpha problem with backplate
Post by: malindis on 2020-10-21, 12:01:35

Hi,
I have just uploaded the files

Title: Re: Alpha problem with backplate
Post by: Beanzvision on 2020-10-21, 13:57:22

Hi Malindis,

Is this what you were trying to do?

(https://forum.corona-renderer.com/index.php?action=dlattach;topic=31318.0;attach=135980;image)

Title: Re: Alpha problem with backplate
Post by: malindis on 2020-10-21, 14:09:06

yes, what am I doing wrong ???

Title: Re: Alpha problem with backplate
Post by: Beanzvision on 2020-10-21, 14:20:47

For your clay material, I enabled "Always black" in the alpha mode.

(https://forum.corona-renderer.com/index.php?action=dlattach;topic=31318.0;attach=135986;image)

Title: Re: Alpha problem with backplate
Post by: malindis on 2020-10-21, 14:24:15

OK but what do I do when I have multiple material assigned to my scene ???

Title: Re: Alpha problem with backplate
Post by: Beanzvision on 2020-10-22, 11:43:48

It should be working by default so it looks like there might be a bug with a light material on a plane when working with the alpha channel. Instead of the background plane, you could replace that with a Corona sky and set the projection to frontal. With a few tweaks, you should get an identical look as to that of the background plane.