How do you matte/alpha glass that's behind other glass ?

[JezUK]

I'm doing an interiors render where there is a glass partition in front of the main exterior windows.

I've made the exterior window glass have a VRayWrapper material with an alpha contribution of -1, and that of course works for the areas of that glass which aren't obscured by other glazing.

But where the partition glazing is in front of that exterior window, no alpha channel mask is present.

How can I overcome this ? (I can't figure a way, I've tried Object ID and WireColor RE).

Thanks.

[stevesideas]

Sounds to me like you will need to do a separate pass for each glass panel.

[Zdravko.Keremidchiev]

Have you tried to set the Affect channels to All channels in the glass partition material?

[JezUK]

Have you tried to set the Affect channels to All channels in the glass partition material?

Thanks Zdravko, that fixed it for me