Recently I was working on a shp to fbx job and found a need,which is "How to set normals on surface".
Thank you very much for help of @ takashi and @ DaveAtSafe.
When Shp's 3D Ploygons are closed geometry, such as the door(test2.shp) in this example, I suggest that there is a conversion tool that can modify the direction of the polygon's points set in shp so that changing the direction of normals in shp is perpendicular to the surface outwards, while this conversion tool is not only applicable to polygons, it should also be applicable to other 3D formats,
At last,I suggest FME to use a conversion tool to convert the normals of closed three-dimensional bodies?which normals direction is perpendicular to the surface.
The following links are the ones I found and similar to my experience.
How to set normals on surface ?
How To Set Normals On Polygon of shp?
Surface Normals Bad Orientation
CityGML-file with LOD1 and LOD2
