Verify front, back of face sketchup is visible view

I have a app to import sketchup file.
I must get texture(color) of face. But, a face have 2 surface: front and back.
And, how to verify what surface is visible to view ?? (Front or back ??).
Please help me !!! (Sorry for my English).
I use C/C++ Sketchup SDK.
Thanh you very much !!!

This is my sketchup file.
table_4.skp (331.8 KB)

Hi khanhpq, hi folks.

Use Monochrome Face Style.



This is in the SDK category, so I presume you are talking about how to do this in your C/C++ code? If I am correct, then there is no way as the visibility of front vs back is a matter of how the object is oriented in the SketchUp GUI viewer not something that can be determined in the model per se. If, on the other hand, you have a solid in your model and are seeking to assure that all its faces have front surface outward, that can be done. I’m not a SDK programmer so I can’t give you details, but the general idea is to examine which way the normal to each face is oriented relative to the interior of your solid.

In sketchup GUI viewer, use monochrome face style. But, i don’t know get from sdk c++ :frowning:

Thanks, i know, but what function to get it from sdk c++ ? do you know …