/// <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;
}
}
}
/// <summary>
/// Delete a vertex from a Delaunay triangulation, ensuring that the
/// triangulation remains Delaunay.
/// </summary>
/// <param name="deltri"></param>
/// <remarks>The origin of 'deltri' is deleted. The union of the triangles
/// adjacent to this vertex is a polygon, for which the Delaunay triangulation
/// is found. Two triangles are removed from the mesh.
///
/// Only interior vertices that do not lie on segments or boundaries
/// may be deleted.
/// </remarks>
internal void DeleteVertex(ref Otri deltri)
{
Otri countingtri = default(Otri);
Otri firstedge = default(Otri), lastedge = default(Otri);
Otri deltriright = default(Otri);
Otri lefttri = default(Otri), righttri = default(Otri);
Otri leftcasing = default(Otri), rightcasing = default(Otri);
Osub leftsubseg = default(Osub), rightsubseg = default(Osub);
Vertex delvertex;
Vertex neworg;
int edgecount;
delvertex = deltri.Org();
VertexDealloc(delvertex);
// Count the degree of the vertex being deleted.
deltri.Onext(ref countingtri);
edgecount = 1;
while (!deltri.Equal(countingtri))
{
edgecount++;
countingtri.OnextSelf();
}
if (edgecount > 3)
{
// Triangulate the polygon defined by the union of all triangles
// adjacent to the vertex being deleted. Check the quality of
// the resulting triangles.
deltri.Onext(ref firstedge);
deltri.Oprev(ref lastedge);
TriangulatePolygon(firstedge, lastedge, edgecount, false, behavior.NoBisect == 0);
}
// Splice out two triangles.
deltri.Lprev(ref deltriright);
deltri.Dnext(ref lefttri);
lefttri.Sym(ref leftcasing);
deltriright.Oprev(ref righttri);
righttri.Sym(ref rightcasing);
deltri.Bond(ref leftcasing);
deltriright.Bond(ref rightcasing);
lefttri.SegPivot(ref leftsubseg);
if (leftsubseg.seg != Mesh.dummysub)
{
deltri.SegBond(ref leftsubseg);
}
righttri.SegPivot(ref rightsubseg);
if (rightsubseg.seg != Mesh.dummysub)
{
deltriright.SegBond(ref rightsubseg);
}
// Set the new origin of 'deltri' and check its quality.
neworg = lefttri.Org();
deltri.SetOrg(neworg);
if (behavior.NoBisect == 0)
{
quality.TestTriangle(ref deltri);
}
// Delete the two spliced-out triangles.
TriangleDealloc(lefttri.triangle);
TriangleDealloc(righttri.triangle);
}