Maya: Render Mattes

mrm.py

"""
Select the geometry to make the renderlayers from.
Will find all the materials (lambert), make a renderlayer per material only showing that material.
"""
import traceback

import pymel.core


selection = pymel.core.ls(selection=True)

shader = pymel.core.shadingNode('lambert', name='no_alpha_mat', asShader=1)
shader.matteOpacity.set(0)
shader.colorR.set(0)
shader.colorG.set(0)
shader.colorB.set(0)

shader_sg = pymel.core.sets(renderable=1, noSurfaceShader=1, empty=1, name='no_alpha_mat_SG')
pymel.core.connectAttr( shader + ".outColor", shader_sg + ".surfaceShader", force=1)

materials = {}
for node in selection:
    for shp in node.getShapes():
        for mat in shp.listConnections(type='shadingEngine'):
            if mat in materials:
                materials[mat].append(node)
            else:
                materials[mat] = [node]

drg = pymel.core.PyNode('defaultRenderGlobals')
for sg in materials:
    mat = None
    try:
        mat = sg.listConnections(type='lambert')[0]
    except:
        continue
    layer = pymel.core.rendering.createRenderLayer(name=mat.name().split(':')[-1], empty=True)
    layer.addMembers(selection)
    layer.setCurrent()
    
    layer.addAdjustments(drg.currentRenderer)
    drg.currentRenderer.set('mayaSoftware')
    
    layer.addAdjustments(drg.imageFormat)
    drg.imageFormat.set(32)

    for node in selection:
        if node not in materials[sg]:
            pymel.core.sets(shader_sg, edit=1, forceElement=node)