Is the way to calculate concavity and convexity between adjacent face works ？

[jianbaoxia]

Hi Bros, I try to extract the AAG (Attributed Adjacency Graph) from my step file. It's a challenge for me to calculate the concavity and convexity between adjacent face. I try to solve it with this way:

I'm not sure whether this is suitable for the curved surface.
I have no idea how to get a point in the surface.
I was try to get normal of surface with the way: TopoDS_Shape → BRepAdaptor_Surface.Surface() → GeomAdaptor_Surface.Surface() → Geom_Surface → GeomLProp_SLProps::Normal (）. However, normal has no location.

I have read the code of "asiAlgo_CheckDihedralAngle::AngleBetweenFaces" in Analysis Situs, it's a long code, deal with many types. As my skill is limited, I can't understand it completely. So I try to calculate concavity and convexity between adjacent face in a simple way. I don't know is it works.

 

[Quaoar]

You may want to google-translate this page: http://quaoar.su/blog/page/issledovanie-telesnogo-ugla
If it's still unclear, I can try to write a brief explanation in the docs of analysis situs.

 

[jianbaoxia]

@Quaoar Your blog is helpful for me, I lack relevant theoretical knowledge，and I will take time to learn with the suggestion of your blog.