As a part of RenderMan for Maya, we provide a RenderMan Procedural that you can use to render XGen hair within Katana. This page will give you the details of how you can render XGen via Katana. I will provide the step-by-step instructions for how to get Katana to render XGen. I've also included the files used to generate the image you see at the end of this page. Below is a render of the example we'll be working with.
Preparation within Maya
The below section describes how to prepare your export in Maya for rendering in Katana. If you have done this, you can skip this section.
In this example, I have assigned a set of per-hair colors based on the values in a texture. In order for RenderMan to accomplish this, we need to output the scalpS and scalpT primitive variable from XGen. In our shading network, we will reference these primvars as we read the texture. I detail how to do this in the Katana section below. Here is a screen snapshot of how the Preview/Output tab of your XGen attributes should look to enable this:
No matter how you want to shade the hair, you MUST click the eye icon in the upper-left corner of the XGen window in order to Update the XGen Preview. This will cause XGen to process the information that it needs when RenderMan procedurally calls it during the render.
Process in Katana
Be sure you have Maya installed and correctly configured for rendering including the appropriate paths seen here.
Because we provide a RenderMan procedural that interfaces with XGen to dynamically create + pass the curves to RenderMan at render-time, the work to get XGen rendering from Katana centers around adding a RenderMan procedural to your scene and configuring the arguments that it requires.