alpha material for compositing

[JoachimArt]

I would love for a composite material in Corona which I can apply to a model and it is not rendered in the beauty pass but only as alpha black or white without casting any shadows or affect anything in the scene in any way. Because there's often cases where I need to render a scene i multiple layers and need to cut certain elements out. If I could just place a plane where I want in the scene and everything behind that plane is rendered black in alpha it would open for so much control with alpha.

[Frood]

If this is nothing you can solve by setting up CMasking* render elements and/or inverted alphas, you can try CoronaMaterial with

- Diffuse, Reflection 0
- Refraction 1, IOR 1, "Thin" disabled(!)
- Advanced options "Alpha mode" -> "Always black" and "Visible in masks" off

as the material on your plane as "alpha cookie cutter". Not perfect because it may affect some distance map calculations or similar but you could use this right now :)


Good Luck

Edit:
Duplicate: https://forum.corona-renderer.com/index.php?topic=27782.msg163585#msg163585

[JoachimArt]

Thanks! that works as a good workaround. Like you said I do not know yet in more advanced scenes with fog etc if it will work (haven't tried yet). So I would still love for a dedicated material for this, but for now this works, cheers!