Regarding the title question, in what scenario are you concerned the data from the C API isn’t valid?
When my model doesn’t have material, I still query UV coords from the function “SUTextureWriterGetFrongFaceUVCoords(…)”. So I want to know if vertex texture UV coords is valid.
What relationship are you trying to resolve?
I assign a material onto component or group, if I want to import component or group material into my application, I need to get UV coords from SUTextureWriterGetFrongFaceUVCoords(…), How do I know the UV coords from C API are related to which component or group material?