Hi
I’m a new vray user - and I’m switching from mr. I’m currently converting a mr scene and have noticed a bug.
The problem occurs when a bitmap is plugged into a multisubtex and then piped into a Colorcorrection node with RBGA = Alph, Alph, Alph, Alph
So I don’t want to duplicate parts of my shader when I just need to use the images alpha channel. This works in mr.
It would also be great if channel mapping worked with RT too.
On a positive note - I’m finding vray good to work with so far. I just realised that you have separate control over maps and shader parameter with opacity which is pretty f-ing sweet!
Hello DPS,
Thank you very much for your feedback.
It seams that Alpha channel is lost when the Bitmap is passed through VrayMultiSubTexture and that’s why it is not possible to use it later in ColorCorrection node.
Unfortunately I can’t think of easy way to workaround it - so probably the only one approach would be to duplicate the same network with all Bitmaps RGB output is set to Alpha, of course with these very complex shading-networks you have that would double the work but at this point I can’t figure out something smarter/easier.
I’ll make a note about this bug into our system - and I’ll let you know when we have it fixed.
Ok, thanks for taking a look.
If it gets looked at in the future it would be great also if I could pass the Alpha channel into a colourtobump node too via a composite map. 
Hello DPS
We would like to inform you that this bug has been fixed , and the fix will be probably available in the next Vray 3.0 beta version.
Great. Thanks guys.