Each Geometry Attribute Node can define as many arbitrary user attributes as needed. For each geometry attribute nodethese, 3Delight for Maya will look for attributes whose name begin with "user user". This prefix is removed from the name and the attribute is output to RIB as a user attribute, along with its value. For instance, a ‘color float3’ attribute named ‘user_colorMultiplier’ will produce a Attribute "colorMultiplier". The supported attribute types are: string, bool, long, long2, long3, float, float2, float3 (color or non-color), double, double2, double3.
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