public int CheckSeg4Encroach(ref Osub testsubseg)
{
double num;
Vertex vertex;
Otri otri = new Otri();
Osub osub = new Osub();
int num1 = 0;
int num2 = 0;
Vertex vertex1 = testsubseg.Org();
Vertex vertex2 = testsubseg.Dest();
testsubseg.TriPivot(ref otri);
if (otri.triangle != Mesh.dummytri)
{
num2++;
vertex = otri.Apex();
num = (vertex1.x - vertex.x) * (vertex2.x - vertex.x) + (vertex1.y - vertex.y) * (vertex2.y - vertex.y);
if (num < 0 && (this.behavior.ConformingDelaunay || num * num >= (2 * this.behavior.goodAngle - 1) * (2 * this.behavior.goodAngle - 1) * ((vertex1.x - vertex.x) * (vertex1.x - vertex.x) + (vertex1.y - vertex.y) * (vertex1.y - vertex.y)) * ((vertex2.x - vertex.x) * (vertex2.x - vertex.x) + (vertex2.y - vertex.y) * (vertex2.y - vertex.y))))
{
num1 = 1;
}
}
testsubseg.Sym(ref osub);
osub.TriPivot(ref otri);
if (otri.triangle != Mesh.dummytri)
{
num2++;
vertex = otri.Apex();
num = (vertex1.x - vertex.x) * (vertex2.x - vertex.x) + (vertex1.y - vertex.y) * (vertex2.y - vertex.y);
if (num < 0 && (this.behavior.ConformingDelaunay || num * num >= (2 * this.behavior.goodAngle - 1) * (2 * this.behavior.goodAngle - 1) * ((vertex1.x - vertex.x) * (vertex1.x - vertex.x) + (vertex1.y - vertex.y) * (vertex1.y - vertex.y)) * ((vertex2.x - vertex.x) * (vertex2.x - vertex.x) + (vertex2.y - vertex.y) * (vertex2.y - vertex.y))))
{
num1 = num1 + 2;
}
}
if (num1 > 0 && (this.behavior.NoBisect == 0 || this.behavior.NoBisect == 1 && num2 == 2))
{
BadSubseg badSubseg = new BadSubseg();
if (num1 != 1)
{
badSubseg.encsubseg = osub;
badSubseg.subsegorg = vertex2;
badSubseg.subsegdest = vertex1;
}
else
{
badSubseg.encsubseg = testsubseg;
badSubseg.subsegorg = vertex1;
badSubseg.subsegdest = vertex2;
}
this.badsubsegs.Enqueue(badSubseg);
}
return(num1);
}
/// <summary>
/// Tag all blind triangles.
/// </summary>
/// <remarks>
/// A triangle is said to be blind if the triangle and its circumcenter
/// lie on two different sides of a constrained edge.
/// </remarks>
private void TagBlindTriangles()
{
int blinded = 0;
Stack <Triangle> triangles;
subsegMap = new Dictionary <int, SubSegment>();
Otri f = default(Otri);
Otri f0 = default(Otri);
Osub e = default(Osub);
Osub sub1 = default(Osub);
// Tag all triangles non-blind
foreach (var t in _TriangleNetMesh.triangles)
{
// Use the infected flag for 'blinded' attribute.
t.infected = false;
}
// for each constrained edge e of cdt do
foreach (var ss in _TriangleNetMesh.subsegs.Values)
{
// Create a stack: triangles
triangles = new Stack <Triangle>();
// for both adjacent triangles fe to e tagged non-blind do
// Push fe into triangles
e.seg = ss;
e.orient = 0;
e.Pivot(ref f);
if (f.tri.id != TriangleNetMesh.DUMMY && !f.tri.infected)
{
triangles.Push(f.tri);
}
e.Sym();
e.Pivot(ref f);
if (f.tri.id != TriangleNetMesh.DUMMY && !f.tri.infected)
{
triangles.Push(f.tri);
}
// while triangles is non-empty
while (triangles.Count > 0)
{
// Pop f from stack triangles
f.tri = triangles.Pop();
f.orient = 0;
// if f is blinded by e (use P) then
if (TriangleIsBlinded(ref f, ref e))
{
// Tag f as blinded by e
f.tri.infected = true;
blinded++;
// Store association triangle -> subseg
subsegMap.Add(f.tri.hash, e.seg);
// for each adjacent triangle f0 to f do
for (f.orient = 0; f.orient < 3; f.orient++)
{
f.Sym(ref f0);
f0.Pivot(ref sub1);
// if f0 is finite and tagged non-blind & the common edge
// between f and f0 is unconstrained then
if (f0.tri.id != TriangleNetMesh.DUMMY && !f0.tri.infected && sub1.seg.hash == TriangleNetMesh.DUMMY)
{
// Push f0 into triangles.
triangles.Push(f0.tri);
}
}
}
}
}
blinded = 0;
}
/// <summary>
/// Check a subsegment to see if it is encroached; add it to the list if it is.
/// </summary>
/// <param name="testsubseg">The subsegment to check.</param>
/// <returns>Returns a nonzero value if the subsegment is encroached.</returns>
/// <remarks>
/// A subsegment is encroached if there is a vertex in its diametral lens.
/// For Ruppert's algorithm (-D switch), the "diametral lens" is the
/// diametral circle. For Chew's algorithm (default), the diametral lens is
/// just big enough to enclose two isosceles triangles whose bases are the
/// subsegment. Each of the two isosceles triangles has two angles equal
/// to 'b.minangle'.
///
/// Chew's algorithm does not require diametral lenses at all--but they save
/// time. Any vertex inside a subsegment's diametral lens implies that the
/// triangle adjoining the subsegment will be too skinny, so it's only a
/// matter of time before the encroaching vertex is deleted by Chew's
/// algorithm. It's faster to simply not insert the doomed vertex in the
/// first place, which is why I use diametral lenses with Chew's algorithm.
/// </remarks>
public int CheckSeg4Encroach(ref Osub testsubseg)
{
Otri neighbortri = default(Otri);
Osub testsym = default(Osub);
BadSubseg encroachedseg;
float dotproduct;
int encroached;
int sides;
Vertex eorg, edest, eapex;
encroached = 0;
sides = 0;
eorg = testsubseg.Org();
edest = testsubseg.Dest();
// Check one neighbor of the subsegment.
testsubseg.TriPivot(ref neighbortri);
// Does the neighbor exist, or is this a boundary edge?
if (neighbortri.triangle != Mesh.dummytri)
{
sides++;
// Find a vertex opposite this subsegment.
eapex = neighbortri.Apex();
// Check whether the apex is in the diametral lens of the subsegment
// (the diametral circle if 'conformdel' is set). A dot product
// of two sides of the triangle is used to check whether the angle
// at the apex is greater than (180 - 2 'minangle') degrees (for
// lenses; 90 degrees for diametral circles).
dotproduct = (eorg.x - eapex.x) * (edest.x - eapex.x) +
(eorg.y - eapex.y) * (edest.y - eapex.y);
if (dotproduct < 0.0)
{
if (behavior.ConformingDelaunay ||
(dotproduct * dotproduct >=
(2.0 * behavior.goodAngle - 1.0) * (2.0 * behavior.goodAngle - 1.0) *
((eorg.x - eapex.x) * (eorg.x - eapex.x) +
(eorg.y - eapex.y) * (eorg.y - eapex.y)) *
((edest.x - eapex.x) * (edest.x - eapex.x) +
(edest.y - eapex.y) * (edest.y - eapex.y))))
{
encroached = 1;
}
}
}
// Check the other neighbor of the subsegment.
testsubseg.Sym(ref testsym);
testsym.TriPivot(ref neighbortri);
// Does the neighbor exist, or is this a boundary edge?
if (neighbortri.triangle != Mesh.dummytri)
{
sides++;
// Find the other vertex opposite this subsegment.
eapex = neighbortri.Apex();
// Check whether the apex is in the diametral lens of the subsegment
// (or the diametral circle, if 'conformdel' is set).
dotproduct = (eorg.x - eapex.x) * (edest.x - eapex.x) +
(eorg.y - eapex.y) * (edest.y - eapex.y);
if (dotproduct < 0.0)
{
if (behavior.ConformingDelaunay ||
(dotproduct * dotproduct >=
(2.0 * behavior.goodAngle - 1.0) * (2.0 * behavior.goodAngle - 1.0) *
((eorg.x - eapex.x) * (eorg.x - eapex.x) +
(eorg.y - eapex.y) * (eorg.y - eapex.y)) *
((edest.x - eapex.x) * (edest.x - eapex.x) +
(edest.y - eapex.y) * (edest.y - eapex.y))))
{
encroached += 2;
}
}
}
if (encroached > 0 && (behavior.NoBisect == 0 || ((behavior.NoBisect == 1) && (sides == 2))))
{
// Add the subsegment to the list of encroached subsegments.
// Be sure to get the orientation right.
encroachedseg = new BadSubseg();
if (encroached == 1)
{
encroachedseg.encsubseg = testsubseg;
encroachedseg.subsegorg = eorg;
encroachedseg.subsegdest = edest;
}
else
{
encroachedseg.encsubseg = testsym;
encroachedseg.subsegorg = edest;
encroachedseg.subsegdest = eorg;
}
badsubsegs.Enqueue(encroachedseg);
}
return(encroached);
}
/// <summary>
/// Find the intersection of an existing segment and a segment that is being
/// inserted. Insert a vertex at the intersection, splitting an existing subsegment.
/// </summary>
/// <param name="splittri"></param>
/// <param name="splitsubseg"></param>
/// <param name="endpoint2"></param>
/// <remarks>
/// The segment being inserted connects the apex of splittri to endpoint2.
/// splitsubseg is the subsegment being split, and MUST adjoin splittri.
/// Hence, endpoints of the subsegment being split are the origin and
/// destination of splittri.
/// On completion, splittri is a handle having the newly inserted
/// intersection point as its origin, and endpoint1 as its destination.
/// </remarks>
private void SegmentIntersection(ref Otri splittri, ref Osub splitsubseg, Vertex endpoint2)
{
Osub opposubseg = default(Osub);
Vertex endpoint1;
Vertex torg, tdest;
Vertex leftvertex, rightvertex;
Vertex newvertex;
InsertVertexResult success;
var dummysub = mesh.dummysub;
double ex, ey;
double tx, ty;
double etx, ety;
double split, denom;
// Find the other three segment endpoints.
endpoint1 = splittri.Apex();
torg = splittri.Org();
tdest = splittri.Dest();
// Segment intersection formulae; see the Antonio reference.
tx = tdest.X - torg.X;
ty = tdest.Y - torg.Y;
ex = endpoint2.X - endpoint1.X;
ey = endpoint2.Y - endpoint1.Y;
etx = torg.X - endpoint2.X;
ety = torg.Y - endpoint2.Y;
denom = ty * ex - tx * ey;
if (denom == 0.0)
{
throw new Exception("Attempt to find intersection of parallel segments.");
}
split = (ey * etx - ex * ety) / denom;
// Create the new vertex.
newvertex = new Vertex(
torg.X + split * (tdest.X - torg.X),
torg.Y + split * (tdest.Y - torg.Y),
splitsubseg.seg.boundary);
newvertex.Id = mesh.hash_vtx++;
mesh.vertices.Add(newvertex.Id, newvertex);
// Insert the intersection vertex. This should always succeed.
success = mesh.InsertVertex(newvertex, ref splittri, ref splitsubseg, false, false);
if (success != InsertVertexResult.Successful)
{
throw new Exception("Failure to split a segment.");
}
// Record a triangle whose origin is the new vertex.
newvertex.tri = splittri;
if (mesh.steinerleft > 0)
{
mesh.steinerleft--;
}
// Divide the segment into two, and correct the segment endpoints.
splitsubseg.Sym();
splitsubseg.Pivot(ref opposubseg);
splitsubseg.Dissolve(dummysub);
opposubseg.Dissolve(dummysub);
do
{
splitsubseg.SetSegOrg(newvertex);
splitsubseg.Next();
} while (splitsubseg.seg.hash != Mesh.DUMMY);
do
{
opposubseg.SetSegOrg(newvertex);
opposubseg.Next();
} while (opposubseg.seg.hash != Mesh.DUMMY);
// Inserting the vertex may have caused edge flips. We wish to rediscover
// the edge connecting endpoint1 to the new intersection vertex.
FindDirection(ref splittri, endpoint1);
rightvertex = splittri.Dest();
leftvertex = splittri.Apex();
if ((leftvertex.X == endpoint1.X) && (leftvertex.Y == endpoint1.Y))
{
splittri.Onext();
}
else if ((rightvertex.X != endpoint1.X) || (rightvertex.Y != endpoint1.Y))
{
throw new Exception("Topological inconsistency after splitting a segment.");
}
// 'splittri' should have destination endpoint1.
}
