Get boundary edges

[stla]

Hello,

Is there a built-in way to get the boundary edges? Otherwise I can do it myself, by taking the edges of all the triangles and then the boundary edges are those which are unique. Maybe there's a better way?

[mdsumner]

there is rgl::boundary3d fwiw

[stla]

@mdsumner Thanks. I found getBoundary3d in rgl. Once you have a R mesh3d, there's also Rvcg::vcgGetEdge. It returns all the edges with an indicator of whether the edge is boundary.

[artem-ogre]

@stla What do you need the boundary edges for?

[stla]

@artem-ogre For plotting, I want to have the possibility to choose the color and the width of the boundary edges.

[mdsumner]

oh and sorry, I thought this was the @stla repo when I replied (not relevant here what R has )

[artem-ogre]

I see. There is no ready-to-use method for getting the boundary edges. So you will have to do it yourself.

If you would like to do it in the most efficient way here are some ideas:

• Only check fixed edges, because only fixed edge can be a boundary edge
• You can do depth-peeling approach (for inspiration check CalculateTriangleDepths and PeelLayer) and record the boundary edges directly after each peeled layer

[stla]

Thanks. I finally use R to get them, with the Rvcg package, which has a function for doing that. This package is based on the C++ library VCGLIB and it is very fast.