Split an intrinsic edge of the mesh by inserting a vertex. This creates a new triangle on either side of the edge (ie a 2-4 split). If the original edge had vertices [a,b], with triangles t0=[a,b,c] and t1=[b,a,d], then the split inserts new vertex f. After the split t0=[a,f,c] and t1=[f,a,d], and we have t2=[f,b,c] and t3=[f,d,b] (it's best to draw it out on paper...) SplitInfo.OriginalTriangles = {t0, t1} and SplitInfo.NewTriangles = {t2, t3}