Glass as separate pass

Not something I ever really bothered with before, but on a current job I have loads of glass and loads of manifestation.
So I want to render the glass as a separate pass. Ive seen it mentioned more than once on here.

So this is what Im doing.
Set all other objects vray properties:
-matte object ON
-alpha -1

On the glass, I just set the refract to black.

When rendering I get black everywhere except the glass (as expected)
The glass showing a reflection of whatever it should be reflecting (as expected)
BUT the objects in the glass reflection are not reflective themselves. So for example, chrome chair leg in the glass reflection is just showing as black.

What am I doing wrong here? How do I have the reflected objects be reflective?

Im also interested in learning this workflow. Would be good for someone to give a quick rundown of how it works :smile:

The issue is most likely related to No GI on other mattes option (vray-properties) - please make sure that this option is OFF and the glass should be exactly the same as the one being rendered without matte-properties.

Looks like that was it thanks