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You can find out all the details of PxrSurface and its layerable parameters by visiting the Pixar Surface Materials.
PxrLayer
We can override the parameter in PxrSurface using PxrLayer. Connect the output of PxrLayer to PxrSurface's PxrLayer.
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We can combine layers using PxrLayerMixer. Connect the output of PxrLayerMixer to PxrSurface's PxrLayer.
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