/// <summary>
/// Create a new subsegment and inserts it between two triangles. Its
/// vertices are properly initialized.
/// </summary>
/// <param name="tri">The new subsegment is inserted at the edge
/// described by this handle.</param>
/// <param name="subsegmark">The marker 'subsegmark' is applied to the
/// subsegment and, if appropriate, its vertices.</param>
internal void InsertSubseg(ref Otri tri, int subsegmark)
{
Otri oppotri = default(Otri);
Osub newsubseg = default(Osub);
Vertex triorg, tridest;
triorg = tri.Org();
tridest = tri.Dest();
// Mark vertices if possible.
if (triorg.mark == 0)
{
triorg.mark = subsegmark;
}
if (tridest.mark == 0)
{
tridest.mark = subsegmark;
}
// Check if there's already a subsegment here.
tri.SegPivot(ref newsubseg);
if (newsubseg.seg == dummysub)
{
// Make new subsegment and initialize its vertices.
MakeSegment(ref newsubseg);
newsubseg.SetOrg(tridest);
newsubseg.SetDest(triorg);
newsubseg.SetSegOrg(tridest);
newsubseg.SetSegDest(triorg);
// Bond new subsegment to the two triangles it is sandwiched between.
// Note that the facing triangle 'oppotri' might be equal to 'dummytri'
// (outer space), but the new subsegment is bonded to it all the same.
tri.SegBond(ref newsubseg);
tri.Sym(ref oppotri);
newsubseg.SymSelf();
oppotri.SegBond(ref newsubseg);
newsubseg.seg.boundary = subsegmark;
}
else
{
if (newsubseg.seg.boundary == 0)
{
newsubseg.seg.boundary = subsegmark;
}
}
}