Would you please illustrate the algorithm of eraseOuterTriangles() and eraseOuterTrianglesAndHoles()

[GeoGroup]

Thanks for your excellent code. I am a liitle confused about the algorithm of eraseOuterTriangles() and eraseOuterTrianglesAndHoles(). For example, the growToBoundary in eraseOuterTriangles make me confused. Would you please add some illustration. As for the eraseOuterTriangles, what is the difference between this method and InPolygon?

Many Thanks.

[artem-ogre]

Hello @GeoGroup,

The removal of triangles works in the following way conceptually:

• It starts by adding triangles adjacent to super-triangle vertices as seeds for the selection
• Then triangle-walking algorithm incrementally adds neighboring triangles to the selection if the shared edge is not a constraint (boundary)
• At the end all triangles outside the outer boundary are selected
• If we remove these triangles from the triangulation we get the result of eraseOuterTriangles
• The process can then be repeated by seeding with triangles that are across the boundary (constraint edges) from the previous selection to calculate 'layers'
• Removing every second layer starting with the outer layer is what eraseOuterTrianlgesAndHoles does

Please let me know if you need any further clarification.

[GeoGroup]

Thank for your reply. My problem is solved. Your solution is very simple and efficient!