VRayEnvironmentFog limitation

[Badbullet]

I was experimenting today with VREnvironmentFog, and came across something I haven't yet figured a way to work around. I was trying to make two different colored fog systems move around each other within separate gizmos. If I make two of these atmospheric effects, and each one is in their own gizmo, the one that is listed first will render in front of the other, even when passing behind it. I believe this is a max limitation, as it does the same with regular fog after testing.

I can make gizmos separate colors by using the VRayDistanceTex with one of them being the inside color, and the other the outside color (or keep adding more VRDT in the outside slot for more colors). But this makes the renders extremely slow of course. I tried to use something like a VRayMultiSubTex and grabbing the mat ID's from the gizmos, but the effect doesn't seem to gather any more info than just the volume to contain the fog.

Is there any way to make different colors for separate gizmos, or a way to have more than 1 VRayEnvironmentFog that allows them to be moved in from in front to back of another?

[vlado]

This is a limitation of 3ds Max that if you have two atmospheric effects, they are layered on top of each other rather than blended. So using the vraydistancetex is probably the best way to go - if you can get away with using some simplified geometry for the distance measurements, it might go faster. Mixing Falloff maps in Distance mode might also be useful, depending on the case.

Best regards,
Vlado

[Badbullet]

Is there also a way to use a shape as a gizmo, and have that gizmo be renderable? Say if I have fog inside of a teapot, and the teapot has an opacity map to reveal reflections in certain spots. The fog gets render artifacts that like coincidental faces. Even if I make a copy of the teapot and set that to renderable and leave the gizmo not renderable. Is there some trick to getting this to work, or is that not a possibility when using geometry as the gizmo?

What I am actually trying to do in the end is having a noise map set as the opacity for the geometry and instanced to fog density. Getting kind of a procedural destruction of geometry showing volume, without doing booleans.

[Zdravko.Keremidchiev]

What sort of artifacts do you get? I made a simple scene but I didn't noticed any issues.
Would it be possible to send us an example scene to support@chaosgroup.com ?

[Badbullet]

I made a quick scene with the issue and sent it. Basically, I get some fog artifacts at the surface of the gizmo where it is has 100% opacity. Make the gizmo not renderable, and the artifacts go away.