So a simple issue. Feeding multiple texture maps into Mantra Classic and Principle Shaders. By multiple maps, I mean take two or more color texture maps, or 2D patterns, combine them using VEX Combine then piping the result into base color of either Classic or Principle shader. THe work takes place in Materials context. Problem is that at times the color maps simply don't show up, all are .rat files, or material shades pure black, and always the resulting materials, while shading is absent, from Oc AOV.
In Materials context create a Material Builder shader, and dive right in.
Inside Material Builder drop down a Classic Shader Core.
Drop two texture nodes pointing to .rat files
Combine using Mix VOP
Pipe Blend out of Mix VOP node into diff_clr of Classic Shader Core
Out of Classic Shader Core pipe layer, F, Of, and Ce into Compute Lighting VOP.
Out of Compute Lighting VOP, pipe Cf, out_Of, and out_F into Surface Output Cf, Of, and F inputs respectively.
Pipe Shader out of Surface Output into output_collect node's shader1 slot.
displacement output is piped into shader2 of output_collector,and appears to work fine.
Material is assigned in Geometry context MaterialSOP to poly geo
Problem is that the material does not appear in Oc AOV.
Oc AOV is defined in mantraROP/images/extra images planes/Oc by adding Occlusion AOV.