this procedure is related to the problem of rendering Maya MASH Color node colours using Arnold. the workaround is complicated. pls don’t blame me. the tutorial where i demonstrate this is → here.
- Create a MASH network from a Polygon object. Add a Color Node, play with the colour distribution.
- Select the MASH_ReproMesh and assign a Shader of your choice, for example an Arnold Surface Shader. Set the colour to green.
- In the ReproMesh-Attributes go to the MASH_ReproMeshShape tab und under Arnold → Export activate Export Vertex Colors.
- Still in the ReproMesh Attribute editor, select the MASH_Repro tab and under → Output Attributes activate Color Per Vertex.
- Display the Attribute editor of the shader you earlier assigned to the MASH_ReproMesh. You can do this by selecting the MASH network in the scene, then right mouse click and choose Material Attributes. It’s the green shader from earlier on.
- Click on the checker icon next to Color and locate the aiUserDataColor node under the Arnold Utilities. Assign that node to the colour. It replaces the green from before.
- Go to the MASH network node, select the Color tab, play with the colours – and render the scene with Arnold!
ian waters demonstrates the same procedure → here. he also pointed me to this tutorial of his which has nothing to do with the MASH Color Node, however: see → here.