Vray GPU - Random UVW & RailClone Color

[duncan_h]

Hi,

Is there anyway to randomize uvw's and use RC Color when using Vray GPU? If I understand correctly the instance engine needs to be off for random UVW but on to use RC Color?

Any tips on alternative methods? I'm mainly interested in having random uvw and the ability to add a random tint.

[iToo]

Hi,

No. I'm afraid it's not possible to use both features at same time with V-Ray GPU.
UVW can be embedded in the geometry disabling the instance engine. But then, V-Ray doesn't recognize the object as a RailClone object (but a mesh), and doesn't apply RailClone Color.

An alternative is to use VRayUVWRandomizer together RailClone Color. In this way: RC Color > VRayBitmap > UVWRandomizer (in the Mapping Source slot). Also Instance Engine must be enabled in RC.
In this case, RailClone UVW options have not effect (including both Segment > Mapping and UVW XForm node). Mapping is handled exclusively by the VRayUWVRandomizer.

[iToo]

A note after some testing here: although the procedure described about should work, we noticed VRayUVWRandomizer doesn't work well with RailClone, when using 'By Instance ID'. All instances get same randomization.

This seems a bug, because it works fine on CPU mode. I just reported the problem to ChaosGroup.