Backface culling culling front face

[Steve T]

Would anyone know why Simply3D would be culling the front face of stl. files and not the backface? Took a while to figure out what was going on as I could see into all my objects. I can turn off culling in the program and see the whole object but that sort of defeats the purpose if I'm trying to save some bytes. 

[Ed Nisley]

> culling the front face of stl. files

At the risk of sounding silly, is your model inside-out?

The 3D printing convention has all the surface normals pointing outward, but it's possible to have a model with all of them pointing inward; in 3D printing terms, that represents a object-shaped bubble of air in universe full of plastic.

If you used an automated repair program on your STL file, it may have "fixed" things by flipping all the normals to the wrong direction.

[Steve T]

Update on this unusual accurance. If anyone is using Cinema4D as their drawing software, or any other drawing software that might be creating this front side culling affect in Simplify3D, I have found that you need to invert all the normals on the model to face inward before exporting as a stl. file. For some reason unknoweth to me, Simplify3D is reversing the normals on import or, more likely Cinema 4D is reversing them on export because models I've loaded from other sources seem to import to Simplify3D fine. Just a FYI.