VRayLightMtl Multi Sub-object Bug

[jujubee]

If you put a VrayLight into a Multi for an object with multiple material IDs, it will not reflect on other surfaces and doesn't contribute to GI if Direct Illumination is checked.
I've had to break apart all my poly models because of this.

[MegaPixel]

Good observation. I wish I knew this prior to my last project. I always struggle to get my VrayLight Materials to behave predictably, And I always tend to use MultiSub materials.

[vlado]

This is a tough one to solve; when you turn on the direct illumination option, V-Ray actually creates a mesh light and renders that instead of the original object. It's somewhat complicated if we only need to create a light for parts of the object, and leave other parts as geometry.

It might be useful to put a short text next to the option that explains this.

Best regards,
Vlado

[jujubee]

Is there a temporary hack for it that would "separate" an object's faces at render time that contains a Vraylightmtl? Tough one to solve, but a fix/implementation would really be appreciated.
This really sucks Vlado cause I use the multimaterial all the time. I have it on a lot of my models such as monitors, etc.

[vlado]

Well, it works fine without the "direct illumination" option, but you'll need a bit higher GI settings.

Best regards,
Vlado