stlAPI_Writer sometimes produces inverted surfaces..

I'm using BRepOffsetAPI_ThruSections with a profile that looks like J, and then save them to stl.
most of the time, the normals of these surfaces would point "outward" (outward here is pointing up for the upper part, pointing down for the lower part, and pointing left for the middle part).

but some times, i get a surface with normals in the opposite direction.
when i write it to IGES it seems alright, but the STL is wrong... how can i fix it?

AGPX's picture

Hi, I found the same problem. I use OCC 6.3.1. Somebody can help?