LPE - specific emissive material

[mikeCG]

Hello !

I am trying to setup a LPE that can isolate a specific emissive material (so all contribution from this material: visible rays, diffuse, reflection, GI)
i tried to use the materialID vop with a tag but i can't quite figure out the expression i should use - nothing seems to work - i get either fullblack, or contribution for all emissive materials

i tried filtering by object too, using objectID or lpe_labels, but i'm confused and can't seem to make any of it work

So i basically want to have "C.*O" --> but filtering only the contribution for my specific material - and not all contribution from all emissive materials

Would you guys know how to do this ?


Thank you very much !

[Dubbie99]

It would be really great to have some sort of repository of LPE examples.
They are extremely hard to figure out from scratch, and all the examples in the docs are kinda useless to be fair - they basically just replicate things you can do with the baked in RE's

[glacierise]

That sounds like a good idea, when we get to do LPEs and USD, will set up a dropbox

[gagui]

Yes, A LPEs repository is needed. Too much time lost trying to figure out simple things...

[psanitra]

+1 from me on the emissive material LPE path, or something like emissive material light select RE. I was wrestling with this the other day too and could not isolate it. As a user case, have a robot with self illuminating parts, need full contribution of that light material on separate AOV/RE. Thanks!

[LeoYfver]

Im sitting now in solaris so im not sure this works in rop context vray.

some days ago we got tags for lights fixed from the dev team:

so this one is like a lightselect. it takes all the rays up until that light you have tagged. You need to add and lpe_label on the light which is the vray tab on the light. I think this maybe only work for solaris for now.
C.*<L.'yourlight'>

for tagging object you can drop down a id drop node a write for example "test" in the string parameter. The tricky one here is that you need to add an "m" before the label.
C.'mtest'.*


https://docs.chaos.com/display/VMAYA...th+Expressions

[bdancer]

> I think this maybe only work for solaris for now.

Works in non-Solaris too.

> The tricky one here is that you need to add an "m" before the label.

m is for material labels, so tricky part here is that you can't used object label started with "m".

[LeoYfver]

>> I think this maybe only work for solaris for now.

>Works in non-Solaris too.

nice!

>> The tricky one here is that you need to add an "m" before the label.

>m is for material labels, so tricky part here is that you can't used object label started with "m".

I know, its just a gotcha sometimes