It would be useful for some particular final render to have multiple render layers where the render can choose material features based on a Render ID. Object ID is a similar precedent.
Is that feature or facsimile already present?
Assuming render layer pre needs to be registered and run
Python Preliminary
import bpy
def renderID2016():
m = bpy.data.materials['UVObject']
n = m.node_tree.nodes
v = n.get("Value")
v.outputs[0].default_value = 5
renderID2016()
Will consider frame_change and render_pre.
Can the materials know the current render layer name or render layer index?
We can set a property for some random variable. Not for any member the variable scene.render.layers .
Failed Attempts
Image above. If you use an Cycles materials as emission, the setting above affects the Cycles lights. Sun Lamps, Point Lights, and these automatic lights are not affected.
