Rendering with V-Ray
Overview
V-Ray is a popular and widely used commercial renderer developed by Chaos Group.
Supported versions
Ornatrix is natively supported by V-Ray for Maya as of version 3.15.01. If you have an older V-Ray version installed you will not be able to render the hair natively, however, you can still render it as geometry.
Rendering the hair
No extra steps are needed to render Ornatrix hair with V-Ray. Simply set the active renderer to V-Ray and Ornatrix hair should be detected and rendered inside the scene.
Per-Strand color
The VRayHairSampler utility node allows you to add different effects top the hair based on the data exported by Ornatrix to VRay, like Curve ID, UVs hair direction and other useful data. In this example we'll see how to add variation to the hair strands using this utility node.
Assign a VRayMtlHair shader to the hair (Or any other shader), create a Ramp Texture node, delete the place2dTexture node (we are not going to needed since Ornatrix is providing the UVs for the hair object) and connect it to the Overall Color input of the VRayMtlHair shader, in the Ramp Texture node select the Ramp Type/Direction, in this case VRamp, change the interpolation method to None and create some colors.
Create a VRayHairSampler (Or a VRayFurSampler if you are shading fur) and connect the Random By Strand output to the V Coord input of the Ramp Texture: This will tell the Ramp Texture how the colors should be distributed in the hair, in this case the color will be randomized by strand using the Curve ID information exported by Ornatrix to VRay.
Hit render and you should see something similar to the image below:
Now you can use the Ramp to determine how the colors are randomized on the hair by changing the positions of the colors and adding other nodes for more interesting effects. Also, this method can be used to tint the hair Along the strand by using the Distance Along Strands output from the VRayHairSampler.
For more information about this utility node go to Chaos Group Documentation
Sample Scene
The sample scene used for this explanation is included in this document for you to test.
VRayPerStrandColors.zip