This is RenderMan 21 Documentation you are viewing. The Rmanwiki home page will redirect you to the current documentation.
Material layering in RenderMan for Houdini is incompatible with other RenderMan bridge products.
You can find out all the details of PxrSurface and it's layerable parameters by visiting the the RenderMan documentation.
In RenderMan for Houdini, we layer the material parameters when its local parameter values have changed from the default values.
If you want to force the default value of the layer to override the layer underneath, you can lock the parameter. This is a workaround since Houdini currently does not provide an option to force the value to be local.
In this example, we set a green diffuse color in PxrSurface. Then we layer a PxrLayer node on top that has a cyan diffuse color.
We can combine layers using PxrLayerMixer. Connect the output of PxrLayerMixer to PxrSurface's PxrLayer.
We can layer specular, iridescence, and other illumination lobes.