Mapping VRayEnvironmentFog emission with colour constant

[seandunderdale]

Hi, Volume light / fog seems to break if I plug a colour constant into the emission slot. Vray RT goes a bit bonkers, takes ages to start and looks different to when I disconnect the colour constant, and use the default colour swatch instead.

Maya 2022.3

V-Ray 5 for Maya, update 2.2

(v5.20.02, revision 31220 from Jan 22 2022)

[hermit.crab]

Hm, it does create a slowdown, which seems to be related to the fog distance (since it works quite fast when the fog is in the gizmo). Is there a reason for using a Color Constant node rather than the integrated color swatch?

[seandunderdale]

I wanted to have a black value and a colour value controlled in a vray multi texture switch. Its not essential, and I can set colour render layer overides, but with a multi texture switch, its more visible to see the colours used. Also, it not only caused a slow down, but an area light, in my test, didnt emit volume rays anymore. It looked like it was disabled from volume light calculation.

[hermit.crab]

Also, it not only caused a slow down, but an area light, in my test, didnt emit volume rays anymore. It looked like it was disabled from volume light calculation.

Could you attach/send a simplified scene for this?

[seandunderdale]

Heres a scene that shows the issue. I have connected up the buggy emission node, so if you start RT itll look very wrong. But swap it out for the other one in the scene and itll look fine.

[hermit.crab]

Plugging a texture into the Emission slots triggers the Raymarching algorithms, which are the cause of the slowdown. If you insist on using a texture switch, you should optimize the Raymarching by increasing the Step size/Texture samples. This, however, would yield lower-quality results. Also, the volume rays are there - they are just barely visible due to the emission (self-illumination of the fog).

[seandunderdale]

ok thanks for looking into it. I just dont think its a god idea to map it the way I did.