Modify a mesh's topology

[dale (Dale Fugier)]

If you need triangles only, the make a copy of the mesh and then call ON_Mesh::ConvertQuadsToTriangles().

There is a sample that is a good demonstration of the workflow.

https://github.com/mcneel/Rhino5Samples_CPP/blob/master/SampleCommands/cmdSampleConvertQuadsToTriangles.cpp