Apply arnold materials to a .usd scene?

[ACCCC]

Hey, i was playing around with the new Arnold USD procedural, i basically exported a scene as .usd from blender and loaded it into max via the USD node.

Is it possible to apply arnold shaders to objects inside that USD file?

[pal.mezei]

Hey @Mr. T!

Yes, it is possible. There are several ways of doing so.

The first one is to use operators to assign materials to shapes inside a procedural. This workflow can be applied to any Arnold procedural.

You can use the SelectOperator menu on the USD procedural https://docs.arnoldrenderer.com/display/A5AF3DSUG/USD#USD-SelectOperator and a Set Parameter operator https://docs.arnoldrenderer.com/display/A5AF3DSUG/Set+Parameter to override the shader.

The second one is to use USD's composition features to change the exported scene without changing the file itself. You can create an "usda" file like this and load it in the procedural instead of the original one.

#usda 1.0
(
    subLayers = [
        @original.usd@
    ]
)

over "MyShape" {
    rel material:binding = </materials/material>
}

def Scope "materials" {

    def Material "material"
    {
        token outputs:arnold:surface.connect = </materials/material/standard_surface.outputs:surface>

        def Shader "standard_surface"
        {
            uniform token info:id = "arnold:standard_surface"
            token outputs:surface
        }
    }

}

[ACCCC]

Thank you,

so i tried to apply a shader with a bitmap connected to the base color input to a simple cube via the operator graph but for some reason it seems that the uv's are not working.

Exporting a alembic file from blender to max works just fine but the uv coordinates in the usd file are either not working or simply not exported.

Is there a way to check the uvw layout inside max?

Or do i have to specify a specific uvw?