Cycles Development Updates

[Kologe]

@zeauro

Why ? You are probably using an Add or Mix shader node to combine two principled shaders.
You can use same nodes to combine volume shader nodes.

You would have choice to :
_ just mix surfaces outputs and obtain an internal automatic mix of volumes ones.
_ mix surfaces outputs and plug one volume output ( potentially from an Holdout shader) in Material Output node.
_ mix surfaces outputs and mix , manually, differently, volume outputs and plug outputs of Mix Shader nodes in 2 sockets of Material Output node.

On the other hand, it is worth noting a sensible setup to mix two surface shaders is a lot more straightforward and flexible to setup (e.g. a uv-mapped bitmap as ‘factor’-input), than it is for volumes.

greetings, Kologe