Chaos Corona Forum

Chaos Corona for Cinema 4D => [C4D] I need help! => Topic started by: hankusp on 2023-10-09, 19:24:47

Title: Newbie question - ho to invert opacity mask bitmap?
Post by: hankusp on 2023-10-09, 19:24:47

How do I invert a black and white bitmap when using it as an opacity mask? I can't find a "invert" button anywhere in the Corona bitmap shader.

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: lollolo on 2023-10-09, 19:45:51

You could use Corona Color Correct, it has an option called "Invert colors"

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: hankusp on 2023-10-10, 00:54:39

thank you a lot

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: Beanzvision on 2023-10-10, 08:30:08

You can also swap the black & white points in the texture :)

(https://forum.corona-renderer.com/index.php?action=dlattach;topic=41110.0;attach=189044;image)

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: hankusp on 2023-10-10, 14:09:42

Yes, I've done it earlier - swaped black and white point. But according to my tests it works much better with Corona Color Correct method.

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: romullus on 2023-10-10, 15:08:48

Keep in mind that Corona color correct invert is not linear. It doesn't matter with purely black and white masks like in your example, but if you want to invert greyscale textures like roughness, or displacement, you will get wrong result. You can use curves editor in Corona color correct if you want to get linear invert.

Title: Re: Newbie question - ho to invert opacity mask bitmap?
Post by: hankusp on 2023-10-10, 15:50:17

Ok, thank you a lot for your tip.