V-Ray Clipper and Rendermasks

[pixelwerk]

As already mentioned in the SKYPE channel, I was running into some issues when using Rendermasks in combination with the V-Ray clipper. I've attached a simple scene where I have two meshes and a clipper. Rendering this works like expected. As soon as I add a Rendermask you can see, even though the alpha is correct, it renders grey parts of the background. When you open the scene and toggle rendermask on and off, you can see what I mean

[vladimir.nedev]

I think this is normal. The clipper is doing its working during the shading stage, while the render mask is applied before that, on the initial intersection.

We can't really fix this without doing the shading as well, which will slow down the render mask and make it sort of useless.

The same problem will appear if you have opacity on your material. The background or other objects will be rendered, where the initial intersection hits the render mask object on places where the opacity map makes it completely transparent.

Greetings,
Vladimir Nedev