Arnold 126.96.36.199 added support for per-light AOVs for volumetrics.
Here’s how to set up per-light AOVs in MtoA 188.8.131.52:
- In the light Attribute Editor, enter a name for the light group.
- Create a custom AOV for the light group. Give the AOV a name that starts with “volume_”. For example, if the light group name is “red”, then the AOV name is “volume_red”.
Here’s a question asked recently. Given a shading tree like the one below, why don’t AOVs like diffuse_direct include the blended color from the Blend Color node?
The answer: because it is the Standard shader that writes the AOV, not the Blend Color shader. The diffuse_direct AOV gets the diffuse layer calculated by the Standard shader, and that’s it.
The MtoA AOV browser shows you what AOVs are implemented by which shaders:
A simple example of using a Color4 Passthrough to create a custom AOV. In this example, I’m using Store Color in Channel to put a per-object Alpha in the custom AOV. I could easily use overrides to do this on a per-partition level.
In this video, I show how to a color mask AOV using a custom AOV and the Utility shader. Topics covered include:
– Creating a custom AOV
– Setting the default shader for a custom AOV
– Setting up the Utility shader to output a color for each shape
– Understanding the difference between the Color and Color ID color modes