/**
* splits the facet incident to h and g into two facets with a new diagonal between the two
* vertices denoted by h and g respectively. The second (new) facet is a copy of the first facet.
* Returns h->next() after the operation, i.e., the new diagonal. The new face is to the right of
* the new diagonal, the old face is to the left. The time is proportional to the distance from h
* to g around the facet.
*/
public Halfedge splitFacet(Halfedge h, Halfedge g) {
if (h == null || g == null) throw new Error("splitFacet: null pointer");
if (h.face != g.face) throw new Error("splitFacet: different incident facets");
if (h == g || h.next == g || g.next == h) {
throw new Error("loops and multiple edges are not allowed");
}
Halfedge<X> newDiagonal = new Halfedge<X>();
Halfedge<X> oppositeNewDiagonal = new Halfedge<X>();
Face<X> newFace = new Face<X>();
newFace.halfedge = g;
newDiagonal.opposite = oppositeNewDiagonal;
oppositeNewDiagonal.opposite = newDiagonal;
newDiagonal.face = h.face;
oppositeNewDiagonal.face = newFace;
// a completer
Halfedge p = h.next;
while (p != g) {
p.face = newFace;
p = p.next;
}
h.next = newDiagonal;
g.next = oppositeNewDiagonal;
return newDiagonal;
}
