/// <summary>
/// Form a Delaunay triangulation by incrementally inserting vertices.
/// </summary>
/// <returns>Returns the number of edges on the convex hull of the
/// triangulation.</returns>
public IMesh Triangulate(IList<Vertex> points, Configuration config)
{
this.mesh = new Mesh(config);
this.mesh.TransferNodes(points);
Otri starttri = new Otri();
// Create a triangular bounding box.
GetBoundingBox();
foreach (var v in mesh.vertices.Values)
{
starttri.tri = mesh.dummytri;
Osub tmp = default(Osub);
if (mesh.InsertVertex(v, ref starttri, ref tmp, false, false) == InsertVertexResult.Duplicate)
{
if (Log.Verbose)
{
Log.Instance.Warning("A duplicate vertex appeared and was ignored.",
"Incremental.Triangulate()");
}
v.type = VertexType.UndeadVertex;
mesh.undeads++;
}
}
// Remove the bounding box.
this.mesh.hullsize = RemoveBox();
return this.mesh;
}
private void FormTopology_Load(object sender, EventArgs e)
{
mesh = (Mesh)GenericMesher.StructuredMesh(new Rectangle(0.0, 0.0, 4.0, 4.0), 4, 4);
renderControl.Initialize(mesh);
topoControlView.PrimitiveCommandInvoked += PrimitiveCommandHandler;
current = default(Otri);
}
/// <summary>
/// Find a new location for a Steiner point.
/// </summary>
/// <param name="org"></param>
/// <param name="dest"></param>
/// <param name="apex"></param>
/// <param name="xi"></param>
/// <param name="eta"></param>
/// <param name="offcenter"></param>
/// <param name="badotri"></param>
/// <returns></returns>
public Point FindLocation(Vertex org, Vertex dest, Vertex apex,
ref double xi, ref double eta, bool offcenter, Otri badotri)
{
// Based on using -U switch, call the corresponding function
if (behavior.MaxAngle == 0.0)
{
return FindNewLocationWithoutMaxAngle(org, dest, apex, ref xi, ref eta, true, badotri);
}
// With max angle
return FindNewLocation(org, dest, apex, ref xi, ref eta, true, badotri);
}
/// <summary>
/// Find the next edge clockwise with the same destination. [dprev(abc) -> cb*]
/// </summary>
public void Dprev(ref Otri ot)
{
//Lnext(ref ot);
ot.tri = tri;
ot.orient = plus1Mod3[orient];
//ot.SymSelf();
int tmp = ot.orient;
ot.orient = ot.tri.neighbors[tmp].orient;
ot.tri = ot.tri.neighbors[tmp].tri;
}
public void Update(Otri otri)
{
if (otri.Triangle == null || otri.Triangle.ID < 0)
{
renderer.SelectTriangle(null, null, null);
}
else
{
renderer.SelectTriangle(otri.Triangle, otri.Org(), otri.Dest());
}
this.Render();
}
/// <summary>
/// Find the previous edge (clockwise) of the adjacent triangle. [rprev(abc) -> b**]
/// </summary>
public void Rprev(ref Otri ot)
{
//Sym(ref ot);
ot.tri = tri.neighbors[orient].tri;
ot.orient = tri.neighbors[orient].orient;
//ot.LprevSelf();
ot.orient = minus1Mod3[ot.orient];
//ot.SymSelf();
int tmp = ot.orient;
ot.orient = ot.tri.neighbors[tmp].orient;
ot.tri = ot.tri.neighbors[tmp].tri;
}
/// <summary>
/// Find the next edge (counterclockwise) of a triangle. [lnext(abc) -> bca]
/// </summary>
public void Lnext(ref Otri ot)
{
ot.tri = tri;
ot.orient = plus1Mod3[orient];
}
/// <summary>
/// Finds a triangle abutting a subsegment.
/// </summary>
internal void Pivot(ref Otri ot)
{
ot = seg.triangles[orient];
}
/// <summary>
/// Test for equality of oriented triangles.
/// </summary>
public bool Equals(Otri ot)
{
return((tri == ot.tri) && (orient == ot.orient));
}
/// <summary>
/// Finds a triangle abutting a subsegment.
/// </summary>
internal void Pivot(ref Otri ot)
{
ot = seg.triangles[orient];
}
/// <summary>
/// Find a triangle or edge containing a given point.
/// </summary>
/// <param name="searchpoint">The point to locate.</param>
/// <param name="searchtri">The triangle to start the search at.</param>
/// <returns>Location information.</returns>
/// <remarks>
/// Searching begins from one of: the input 'searchtri', a recently
/// encountered triangle 'recenttri', or from a triangle chosen from a
/// random sample. The choice is made by determining which triangle's
/// origin is closest to the point we are searching for. Normally,
/// 'searchtri' should be a handle on the convex hull of the triangulation.
///
/// Details on the random sampling method can be found in the Mucke, Saias,
/// and Zhu paper cited in the header of this code.
///
/// On completion, 'searchtri' is a triangle that contains 'searchpoint'.
///
/// Returns ONVERTEX if the point lies on an existing vertex. 'searchtri'
/// is a handle whose origin is the existing vertex.
///
/// Returns ONEDGE if the point lies on a mesh edge. 'searchtri' is a
/// handle whose primary edge is the edge on which the point lies.
///
/// Returns INTRIANGLE if the point lies strictly within a triangle.
/// 'searchtri' is a handle on the triangle that contains the point.
///
/// Returns OUTSIDE if the point lies outside the mesh. 'searchtri' is a
/// handle whose primary edge the point is to the right of. This might
/// occur when the circumcenter of a triangle falls just slightly outside
/// the mesh due to floating-point roundoff error. It also occurs when
/// seeking a hole or region point that a foolish user has placed outside
/// the mesh.
///
/// WARNING: This routine is designed for convex triangulations, and will
/// not generally work after the holes and concavities have been carved.
/// </remarks>
public LocateResult Locate(Point searchpoint, ref Otri searchtri)
{
Otri sampletri = default(Otri);
Vertex torg, tdest;
double searchdist, dist;
double ahead;
// Record the distance from the suggested starting triangle to the
// point we seek.
torg = searchtri.Org();
searchdist = (searchpoint.x - torg.x) * (searchpoint.x - torg.x) +
(searchpoint.y - torg.y) * (searchpoint.y - torg.y);
// If a recently encountered triangle has been recorded and has not been
// deallocated, test it as a good starting point.
if (recenttri.tri != null)
{
if (!Otri.IsDead(recenttri.tri))
{
torg = recenttri.Org();
if ((torg.x == searchpoint.x) && (torg.y == searchpoint.y))
{
recenttri.Copy(ref searchtri);
return LocateResult.OnVertex;
}
dist = (searchpoint.x - torg.x) * (searchpoint.x - torg.x) +
(searchpoint.y - torg.y) * (searchpoint.y - torg.y);
if (dist < searchdist)
{
recenttri.Copy(ref searchtri);
searchdist = dist;
}
}
}
// TODO: Improve sampling.
sampler.Update();
foreach (var t in sampler)
{
sampletri.tri = t;
if (!Otri.IsDead(sampletri.tri))
{
torg = sampletri.Org();
dist = (searchpoint.x - torg.x) * (searchpoint.x - torg.x) +
(searchpoint.y - torg.y) * (searchpoint.y - torg.y);
if (dist < searchdist)
{
sampletri.Copy(ref searchtri);
searchdist = dist;
}
}
}
// Where are we?
torg = searchtri.Org();
tdest = searchtri.Dest();
// Check the starting triangle's vertices.
if ((torg.x == searchpoint.x) && (torg.y == searchpoint.y))
{
return LocateResult.OnVertex;
}
if ((tdest.x == searchpoint.x) && (tdest.y == searchpoint.y))
{
searchtri.Lnext();
return LocateResult.OnVertex;
}
// Orient 'searchtri' to fit the preconditions of calling preciselocate().
ahead = predicates.CounterClockwise(torg, tdest, searchpoint);
if (ahead < 0.0)
{
// Turn around so that 'searchpoint' is to the left of the
// edge specified by 'searchtri'.
searchtri.Sym();
}
else if (ahead == 0.0)
{
// Check if 'searchpoint' is between 'torg' and 'tdest'.
if (((torg.x < searchpoint.x) == (searchpoint.x < tdest.x)) &&
((torg.y < searchpoint.y) == (searchpoint.y < tdest.y)))
{
return LocateResult.OnEdge;
}
}
return PreciseLocate(searchpoint, ref searchtri, false);
}
/// <summary>
/// Insert a vertex into a Delaunay triangulation, performing flips as necessary
/// to maintain the Delaunay property.
/// </summary>
/// <param name="newvertex">The point to be inserted.</param>
/// <param name="searchtri">The triangle to start the search.</param>
/// <param name="splitseg">Segment to split.</param>
/// <param name="segmentflaws">Check for creation of encroached subsegments.</param>
/// <param name="triflaws">Check for creation of bad quality triangles.</param>
/// <returns>If a duplicate vertex or violated segment does not prevent the
/// vertex from being inserted, the return value will be ENCROACHINGVERTEX if
/// the vertex encroaches upon a subsegment (and checking is enabled), or
/// SUCCESSFULVERTEX otherwise. In either case, 'searchtri' is set to a handle
/// whose origin is the newly inserted vertex.</returns>
/// <remarks>
/// The point 'newvertex' is located. If 'searchtri.triangle' is not NULL,
/// the search for the containing triangle begins from 'searchtri'. If
/// 'searchtri.triangle' is NULL, a full point location procedure is called.
/// If 'insertvertex' is found inside a triangle, the triangle is split into
/// three; if 'insertvertex' lies on an edge, the edge is split in two,
/// thereby splitting the two adjacent triangles into four. Edge flips are
/// used to restore the Delaunay property. If 'insertvertex' lies on an
/// existing vertex, no action is taken, and the value DUPLICATEVERTEX is
/// returned. On return, 'searchtri' is set to a handle whose origin is the
/// existing vertex.
///
/// InsertVertex() does not use flip() for reasons of speed; some
/// information can be reused from edge flip to edge flip, like the
/// locations of subsegments.
///
/// Param 'splitseg': Normally, the parameter 'splitseg' is set to NULL,
/// implying that no subsegment should be split. In this case, if 'insertvertex'
/// is found to lie on a segment, no action is taken, and the value VIOLATINGVERTEX
/// is returned. On return, 'searchtri' is set to a handle whose primary edge is the
/// violated subsegment.
/// If the calling routine wishes to split a subsegment by inserting a vertex in it,
/// the parameter 'splitseg' should be that subsegment. In this case, 'searchtri'
/// MUST be the triangle handle reached by pivoting from that subsegment; no point
/// location is done.
///
/// Param 'segmentflaws': Flags that indicate whether or not there should
/// be checks for the creation of encroached subsegments. If a newly inserted
/// vertex encroaches upon subsegments, these subsegments are added to the list
/// of subsegments to be split if 'segmentflaws' is set.
///
/// Param 'triflaws': Flags that indicate whether or not there should be
/// checks for the creation of bad quality triangles. If bad triangles are
/// created, these are added to the queue if 'triflaws' is set.
/// </remarks>
internal InsertVertexResult InsertVertex(Vertex newvertex, ref Otri searchtri,
ref Osub splitseg, bool segmentflaws, bool triflaws)
{
Otri horiz = default(Otri);
Otri top = default(Otri);
Otri botleft = default(Otri), botright = default(Otri);
Otri topleft = default(Otri), topright = default(Otri);
Otri newbotleft = default(Otri), newbotright = default(Otri);
Otri newtopright = default(Otri);
Otri botlcasing = default(Otri), botrcasing = default(Otri);
Otri toplcasing = default(Otri), toprcasing = default(Otri);
Otri testtri = default(Otri);
Osub botlsubseg = default(Osub), botrsubseg = default(Osub);
Osub toplsubseg = default(Osub), toprsubseg = default(Osub);
Osub brokensubseg = default(Osub);
Osub checksubseg = default(Osub);
Osub rightsubseg = default(Osub);
Osub newsubseg = default(Osub);
BadSubseg encroached;
//FlipStacker newflip;
Vertex first;
Vertex leftvertex, rightvertex, botvertex, topvertex, farvertex;
Vertex segmentorg, segmentdest;
int region;
double area;
InsertVertexResult success;
LocateResult intersect;
bool doflip;
bool mirrorflag;
bool enq;
if (splitseg.seg == null)
{
// Find the location of the vertex to be inserted. Check if a good
// starting triangle has already been provided by the caller.
if (searchtri.tri.id == DUMMY)
{
// Find a boundary triangle.
horiz.tri = dummytri;
horiz.orient = 0;
horiz.Sym();
// Search for a triangle containing 'newvertex'.
intersect = locator.Locate(newvertex, ref horiz);
}
else
{
// Start searching from the triangle provided by the caller.
searchtri.Copy(ref horiz);
intersect = locator.PreciseLocate(newvertex, ref horiz, true);
}
}
else
{
// The calling routine provides the subsegment in which
// the vertex is inserted.
searchtri.Copy(ref horiz);
intersect = LocateResult.OnEdge;
}
if (intersect == LocateResult.OnVertex)
{
// There's already a vertex there. Return in 'searchtri' a triangle
// whose origin is the existing vertex.
horiz.Copy(ref searchtri);
locator.Update(ref horiz);
return InsertVertexResult.Duplicate;
}
if ((intersect == LocateResult.OnEdge) || (intersect == LocateResult.Outside))
{
// The vertex falls on an edge or boundary.
if (checksegments && (splitseg.seg == null))
{
// Check whether the vertex falls on a subsegment.
horiz.Pivot(ref brokensubseg);
if (brokensubseg.seg.hash != DUMMY)
{
// The vertex falls on a subsegment, and hence will not be inserted.
if (segmentflaws)
{
enq = behavior.NoBisect != 2;
if (enq && (behavior.NoBisect == 1))
{
// This subsegment may be split only if it is an
// internal boundary.
horiz.Sym(ref testtri);
enq = testtri.tri.id != DUMMY;
}
if (enq)
{
// Add the subsegment to the list of encroached subsegments.
encroached = new BadSubseg();
encroached.subseg = brokensubseg;
encroached.org = brokensubseg.Org();
encroached.dest = brokensubseg.Dest();
qualityMesher.AddBadSubseg(encroached);
}
}
// Return a handle whose primary edge contains the vertex,
// which has not been inserted.
horiz.Copy(ref searchtri);
locator.Update(ref horiz);
return InsertVertexResult.Violating;
}
}
// Insert the vertex on an edge, dividing one triangle into two (if
// the edge lies on a boundary) or two triangles into four.
horiz.Lprev(ref botright);
botright.Sym(ref botrcasing);
horiz.Sym(ref topright);
// Is there a second triangle? (Or does this edge lie on a boundary?)
mirrorflag = topright.tri.id != DUMMY;
if (mirrorflag)
{
topright.Lnext();
topright.Sym(ref toprcasing);
MakeTriangle(ref newtopright);
}
else
{
// Splitting a boundary edge increases the number of boundary edges.
hullsize++;
}
MakeTriangle(ref newbotright);
// Set the vertices of changed and new triangles.
rightvertex = horiz.Org();
leftvertex = horiz.Dest();
botvertex = horiz.Apex();
newbotright.SetOrg(botvertex);
newbotright.SetDest(rightvertex);
newbotright.SetApex(newvertex);
horiz.SetOrg(newvertex);
// Set the region of a new triangle.
newbotright.tri.label = botright.tri.label;
if (behavior.VarArea)
{
// Set the area constraint of a new triangle.
newbotright.tri.area = botright.tri.area;
}
if (mirrorflag)
{
topvertex = topright.Dest();
newtopright.SetOrg(rightvertex);
newtopright.SetDest(topvertex);
newtopright.SetApex(newvertex);
topright.SetOrg(newvertex);
// Set the region of another new triangle.
newtopright.tri.label = topright.tri.label;
if (behavior.VarArea)
{
// Set the area constraint of another new triangle.
newtopright.tri.area = topright.tri.area;
}
}
// There may be subsegments that need to be bonded
// to the new triangle(s).
if (checksegments)
{
botright.Pivot(ref botrsubseg);
if (botrsubseg.seg.hash != DUMMY)
{
botright.SegDissolve(dummysub);
newbotright.SegBond(ref botrsubseg);
}
if (mirrorflag)
{
topright.Pivot(ref toprsubseg);
if (toprsubseg.seg.hash != DUMMY)
{
topright.SegDissolve(dummysub);
newtopright.SegBond(ref toprsubseg);
}
}
}
// Bond the new triangle(s) to the surrounding triangles.
newbotright.Bond(ref botrcasing);
newbotright.Lprev();
newbotright.Bond(ref botright);
newbotright.Lprev();
if (mirrorflag)
{
newtopright.Bond(ref toprcasing);
newtopright.Lnext();
newtopright.Bond(ref topright);
newtopright.Lnext();
newtopright.Bond(ref newbotright);
}
if (splitseg.seg != null)
{
// Split the subsegment into two.
splitseg.SetDest(newvertex);
segmentorg = splitseg.SegOrg();
segmentdest = splitseg.SegDest();
splitseg.Sym();
splitseg.Pivot(ref rightsubseg);
InsertSubseg(ref newbotright, splitseg.seg.boundary);
newbotright.Pivot(ref newsubseg);
newsubseg.SetSegOrg(segmentorg);
newsubseg.SetSegDest(segmentdest);
splitseg.Bond(ref newsubseg);
newsubseg.Sym();
newsubseg.Bond(ref rightsubseg);
splitseg.Sym();
// Transfer the subsegment's boundary marker to the vertex if required.
if (newvertex.label == 0)
{
newvertex.label = splitseg.seg.boundary;
}
}
if (checkquality)
{
flipstack.Clear();
flipstack.Push(default(Otri)); // Dummy flip (see UndoVertex)
flipstack.Push(horiz);
}
// Position 'horiz' on the first edge to check for
// the Delaunay property.
horiz.Lnext();
}
else
{
// Insert the vertex in a triangle, splitting it into three.
horiz.Lnext(ref botleft);
horiz.Lprev(ref botright);
botleft.Sym(ref botlcasing);
botright.Sym(ref botrcasing);
MakeTriangle(ref newbotleft);
MakeTriangle(ref newbotright);
// Set the vertices of changed and new triangles.
rightvertex = horiz.Org();
leftvertex = horiz.Dest();
botvertex = horiz.Apex();
newbotleft.SetOrg(leftvertex);
newbotleft.SetDest(botvertex);
newbotleft.SetApex(newvertex);
newbotright.SetOrg(botvertex);
newbotright.SetDest(rightvertex);
newbotright.SetApex(newvertex);
horiz.SetApex(newvertex);
// Set the region of the new triangles.
newbotleft.tri.label = horiz.tri.label;
newbotright.tri.label = horiz.tri.label;
if (behavior.VarArea)
{
// Set the area constraint of the new triangles.
area = horiz.tri.area;
newbotleft.tri.area = area;
newbotright.tri.area = area;
}
// There may be subsegments that need to be bonded
// to the new triangles.
if (checksegments)
{
botleft.Pivot(ref botlsubseg);
if (botlsubseg.seg.hash != DUMMY)
{
botleft.SegDissolve(dummysub);
newbotleft.SegBond(ref botlsubseg);
}
botright.Pivot(ref botrsubseg);
if (botrsubseg.seg.hash != DUMMY)
{
botright.SegDissolve(dummysub);
newbotright.SegBond(ref botrsubseg);
}
}
// Bond the new triangles to the surrounding triangles.
newbotleft.Bond(ref botlcasing);
newbotright.Bond(ref botrcasing);
newbotleft.Lnext();
newbotright.Lprev();
newbotleft.Bond(ref newbotright);
newbotleft.Lnext();
botleft.Bond(ref newbotleft);
newbotright.Lprev();
botright.Bond(ref newbotright);
if (checkquality)
{
flipstack.Clear();
flipstack.Push(horiz);
}
}
// The insertion is successful by default, unless an encroached
// subsegment is found.
success = InsertVertexResult.Successful;
if (newvertex.tri.tri != null)
{
// Store the coordinates of the triangle that contains newvertex.
newvertex.tri.SetOrg(rightvertex);
newvertex.tri.SetDest(leftvertex);
newvertex.tri.SetApex(botvertex);
}
// Circle around the newly inserted vertex, checking each edge opposite it
// for the Delaunay property. Non-Delaunay edges are flipped. 'horiz' is
// always the edge being checked. 'first' marks where to stop circling.
first = horiz.Org();
rightvertex = first;
leftvertex = horiz.Dest();
// Circle until finished.
while (true)
{
// By default, the edge will be flipped.
doflip = true;
if (checksegments)
{
// Check for a subsegment, which cannot be flipped.
horiz.Pivot(ref checksubseg);
if (checksubseg.seg.hash != DUMMY)
{
// The edge is a subsegment and cannot be flipped.
doflip = false;
if (segmentflaws)
{
// Does the new vertex encroach upon this subsegment?
if (qualityMesher.CheckSeg4Encroach(ref checksubseg) > 0)
{
success = InsertVertexResult.Encroaching;
}
}
}
}
if (doflip)
{
// Check if the edge is a boundary edge.
horiz.Sym(ref top);
if (top.tri.id == DUMMY)
{
// The edge is a boundary edge and cannot be flipped.
doflip = false;
}
else
{
// Find the vertex on the other side of the edge.
farvertex = top.Apex();
// In the incremental Delaunay triangulation algorithm, any of
// 'leftvertex', 'rightvertex', and 'farvertex' could be vertices
// of the triangular bounding box. These vertices must be
// treated as if they are infinitely distant, even though their
// "coordinates" are not.
if ((leftvertex == infvertex1) || (leftvertex == infvertex2) ||
(leftvertex == infvertex3))
{
// 'leftvertex' is infinitely distant. Check the convexity of
// the boundary of the triangulation. 'farvertex' might be
// infinite as well, but trust me, this same condition should
// be applied.
doflip = predicates.CounterClockwise(newvertex, rightvertex, farvertex) > 0.0;
}
else if ((rightvertex == infvertex1) ||
(rightvertex == infvertex2) ||
(rightvertex == infvertex3))
{
// 'rightvertex' is infinitely distant. Check the convexity of
// the boundary of the triangulation. 'farvertex' might be
// infinite as well, but trust me, this same condition should
// be applied.
doflip = predicates.CounterClockwise(farvertex, leftvertex, newvertex) > 0.0;
}
else if ((farvertex == infvertex1) ||
(farvertex == infvertex2) ||
(farvertex == infvertex3))
{
// 'farvertex' is infinitely distant and cannot be inside
// the circumcircle of the triangle 'horiz'.
doflip = false;
}
else
{
// Test whether the edge is locally Delaunay.
doflip = predicates.InCircle(leftvertex, newvertex, rightvertex, farvertex) > 0.0;
}
if (doflip)
{
// We made it! Flip the edge 'horiz' by rotating its containing
// quadrilateral (the two triangles adjacent to 'horiz').
// Identify the casing of the quadrilateral.
top.Lprev(ref topleft);
topleft.Sym(ref toplcasing);
top.Lnext(ref topright);
topright.Sym(ref toprcasing);
horiz.Lnext(ref botleft);
botleft.Sym(ref botlcasing);
horiz.Lprev(ref botright);
botright.Sym(ref botrcasing);
// Rotate the quadrilateral one-quarter turn counterclockwise.
topleft.Bond(ref botlcasing);
botleft.Bond(ref botrcasing);
botright.Bond(ref toprcasing);
topright.Bond(ref toplcasing);
if (checksegments)
{
// Check for subsegments and rebond them to the quadrilateral.
topleft.Pivot(ref toplsubseg);
botleft.Pivot(ref botlsubseg);
botright.Pivot(ref botrsubseg);
topright.Pivot(ref toprsubseg);
if (toplsubseg.seg.hash == DUMMY)
{
topright.SegDissolve(dummysub);
}
else
{
topright.SegBond(ref toplsubseg);
}
if (botlsubseg.seg.hash == DUMMY)
{
topleft.SegDissolve(dummysub);
}
else
{
topleft.SegBond(ref botlsubseg);
}
if (botrsubseg.seg.hash == DUMMY)
{
botleft.SegDissolve(dummysub);
}
else
{
botleft.SegBond(ref botrsubseg);
}
if (toprsubseg.seg.hash == DUMMY)
{
botright.SegDissolve(dummysub);
}
else
{
botright.SegBond(ref toprsubseg);
}
}
// New vertex assignments for the rotated quadrilateral.
horiz.SetOrg(farvertex);
horiz.SetDest(newvertex);
horiz.SetApex(rightvertex);
top.SetOrg(newvertex);
top.SetDest(farvertex);
top.SetApex(leftvertex);
// Assign region.
// TODO: check region ok (no Math.Min necessary)
region = Math.Min(top.tri.label, horiz.tri.label);
top.tri.label = region;
horiz.tri.label = region;
if (behavior.VarArea)
{
if ((top.tri.area <= 0.0) || (horiz.tri.area <= 0.0))
{
area = -1.0;
}
else
{
// Take the average of the two triangles' area constraints.
// This prevents small area constraints from migrating a
// long, long way from their original location due to flips.
area = 0.5 * (top.tri.area + horiz.tri.area);
}
top.tri.area = area;
horiz.tri.area = area;
}
if (checkquality)
{
flipstack.Push(horiz);
}
// On the next iterations, consider the two edges that were exposed (this
// is, are now visible to the newly inserted vertex) by the edge flip.
horiz.Lprev();
leftvertex = farvertex;
}
}
}
if (!doflip)
{
// The handle 'horiz' is accepted as locally Delaunay.
if (triflaws)
{
// Check the triangle 'horiz' for quality.
qualityMesher.TestTriangle(ref horiz);
}
// Look for the next edge around the newly inserted vertex.
horiz.Lnext();
horiz.Sym(ref testtri);
// Check for finishing a complete revolution about the new vertex, or
// falling outside of the triangulation. The latter will happen when
// a vertex is inserted at a boundary.
if ((leftvertex == first) || (testtri.tri.id == DUMMY))
{
// We're done. Return a triangle whose origin is the new vertex.
horiz.Lnext(ref searchtri);
Otri recenttri = default(Otri);
horiz.Lnext(ref recenttri);
locator.Update(ref recenttri);
return success;
}
// Finish finding the next edge around the newly inserted vertex.
testtri.Lnext(ref horiz);
rightvertex = leftvertex;
leftvertex = horiz.Dest();
}
}
}
/// <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.Equals(countingtri))
{
edgecount++;
countingtri.Onext();
}
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.Pivot(ref leftsubseg);
if (leftsubseg.seg.hash != DUMMY)
{
deltri.SegBond(ref leftsubseg);
}
righttri.Pivot(ref rightsubseg);
if (rightsubseg.seg.hash != DUMMY)
{
deltriright.SegBond(ref rightsubseg);
}
// Set the new origin of 'deltri' and check its quality.
neworg = lefttri.Org();
deltri.SetOrg(neworg);
if (behavior.NoBisect == 0)
{
qualityMesher.TestTriangle(ref deltri);
}
// Delete the two spliced-out triangles.
TriangleDealloc(lefttri.tri);
TriangleDealloc(righttri.tri);
}
SplayNode CircleTopInsert(SplayNode splayroot, Otri newkey,
Vertex pa, Vertex pb, Vertex pc, double topy)
{
double ccwabc;
double xac, yac, xbc, ybc;
double aclen2, bclen2;
Point searchpoint = new Point(); // TODO: mesh.nextras
Otri dummytri = default(Otri);
ccwabc = predicates.CounterClockwise(pa, pb, pc);
xac = pa.x - pc.x;
yac = pa.y - pc.y;
xbc = pb.x - pc.x;
ybc = pb.y - pc.y;
aclen2 = xac * xac + yac * yac;
bclen2 = xbc * xbc + ybc * ybc;
searchpoint.x = pc.x - (yac * bclen2 - ybc * aclen2) / (2.0 * ccwabc);
searchpoint.y = topy;
return SplayInsert(Splay(splayroot, searchpoint, ref dummytri), newkey, searchpoint);
}
SplayNode FrontLocate(SplayNode splayroot, Otri bottommost, Vertex searchvertex,
ref Otri searchtri, ref bool farright)
{
bool farrightflag;
bottommost.Copy(ref searchtri);
splayroot = Splay(splayroot, searchvertex, ref searchtri);
farrightflag = false;
while (!farrightflag && RightOfHyperbola(ref searchtri, searchvertex))
{
searchtri.Onext();
farrightflag = searchtri.Equals(bottommost);
}
farright = farrightflag;
return splayroot;
}
SplayNode SplayInsert(SplayNode splayroot, Otri newkey, Point searchpoint)
{
SplayNode newsplaynode;
newsplaynode = new SplayNode(); //poolalloc(m.splaynodes);
splaynodes.Add(newsplaynode);
newkey.Copy(ref newsplaynode.keyedge);
newsplaynode.keydest = newkey.Dest();
if (splayroot == null)
{
newsplaynode.lchild = null;
newsplaynode.rchild = null;
}
else if (RightOfHyperbola(ref splayroot.keyedge, searchpoint))
{
newsplaynode.lchild = splayroot;
newsplaynode.rchild = splayroot.rchild;
splayroot.rchild = null;
}
else
{
newsplaynode.lchild = splayroot.lchild;
newsplaynode.rchild = splayroot;
splayroot.lchild = null;
}
return newsplaynode;
}
SplayNode Splay(SplayNode splaytree, Point searchpoint, ref Otri searchtri)
{
SplayNode child, grandchild;
SplayNode lefttree, righttree;
SplayNode leftright;
Vertex checkvertex;
bool rightofroot, rightofchild;
if (splaytree == null)
{
return null;
}
checkvertex = splaytree.keyedge.Dest();
if (checkvertex == splaytree.keydest)
{
rightofroot = RightOfHyperbola(ref splaytree.keyedge, searchpoint);
if (rightofroot)
{
splaytree.keyedge.Copy(ref searchtri);
child = splaytree.rchild;
}
else
{
child = splaytree.lchild;
}
if (child == null)
{
return splaytree;
}
checkvertex = child.keyedge.Dest();
if (checkvertex != child.keydest)
{
child = Splay(child, searchpoint, ref searchtri);
if (child == null)
{
if (rightofroot)
{
splaytree.rchild = null;
}
else
{
splaytree.lchild = null;
}
return splaytree;
}
}
rightofchild = RightOfHyperbola(ref child.keyedge, searchpoint);
if (rightofchild)
{
child.keyedge.Copy(ref searchtri);
grandchild = Splay(child.rchild, searchpoint, ref searchtri);
child.rchild = grandchild;
}
else
{
grandchild = Splay(child.lchild, searchpoint, ref searchtri);
child.lchild = grandchild;
}
if (grandchild == null)
{
if (rightofroot)
{
splaytree.rchild = child.lchild;
child.lchild = splaytree;
}
else
{
splaytree.lchild = child.rchild;
child.rchild = splaytree;
}
return child;
}
if (rightofchild)
{
if (rightofroot)
{
splaytree.rchild = child.lchild;
child.lchild = splaytree;
}
else
{
splaytree.lchild = grandchild.rchild;
grandchild.rchild = splaytree;
}
child.rchild = grandchild.lchild;
grandchild.lchild = child;
}
else
{
if (rightofroot)
{
splaytree.rchild = grandchild.lchild;
grandchild.lchild = splaytree;
}
else
{
splaytree.lchild = child.rchild;
child.rchild = splaytree;
}
child.lchild = grandchild.rchild;
grandchild.rchild = child;
}
return grandchild;
}
else
{
lefttree = Splay(splaytree.lchild, searchpoint, ref searchtri);
righttree = Splay(splaytree.rchild, searchpoint, ref searchtri);
splaynodes.Remove(splaytree);
if (lefttree == null)
{
return righttree;
}
else if (righttree == null)
{
return lefttree;
}
else if (lefttree.rchild == null)
{
lefttree.rchild = righttree.lchild;
righttree.lchild = lefttree;
return righttree;
}
else if (righttree.lchild == null)
{
righttree.lchild = lefttree.rchild;
lefttree.rchild = righttree;
return lefttree;
}
else
{
// printf("Holy Toledo!!!\n");
leftright = lefttree.rchild;
while (leftright.rchild != null)
{
leftright = leftright.rchild;
}
leftright.rchild = righttree;
return lefttree;
}
}
}
// The following primitives are all described by Guibas and Stolfi.
// However, Guibas and Stolfi use an edge-based data structure,
// whereas I use a triangle-based data structure.
//
// lnext: finds the next edge (counterclockwise) of a triangle.
//
// onext: spins counterclockwise around a vertex; that is, it finds
// the next edge with the same origin in the counterclockwise direction. This
// edge is part of a different triangle.
//
// oprev: spins clockwise around a vertex; that is, it finds the
// next edge with the same origin in the clockwise direction. This edge is
// part of a different triangle.
//
// dnext: spins counterclockwise around a vertex; that is, it finds
// the next edge with the same destination in the counterclockwise direction.
// This edge is part of a different triangle.
//
// dprev: spins clockwise around a vertex; that is, it finds the
// next edge with the same destination in the clockwise direction. This edge
// is part of a different triangle.
//
// rnext: moves one edge counterclockwise about the adjacent
// triangle. (It's best understood by reading Guibas and Stolfi. It
// involves changing triangles twice.)
//
// rprev: moves one edge clockwise about the adjacent triangle.
// (It's best understood by reading Guibas and Stolfi. It involves
// changing triangles twice.)
/// <summary>
/// Find the abutting triangle; same edge. [sym(abc) -> ba*]
/// </summary>
/// Note that the edge direction is necessarily reversed, because the handle specified
/// by an oriented triangle is directed counterclockwise around the triangle.
/// </remarks>
public void Sym(ref Otri ot)
{
ot.tri = tri.neighbors[orient].tri;
ot.orient = tri.neighbors[orient].orient;
}
/// <summary>
/// Transform two triangles to two different triangles by flipping an edge
/// clockwise within a quadrilateral. Reverses the flip() operation so that
/// the data structures representing the triangles are back where they were
/// before the flip().
/// </summary>
/// <param name="flipedge"></param>
/// <remarks>
/// See above Flip() remarks for more information.
///
/// Upon completion of this routine, the 'flipedge' handle holds the edge
/// cd of triangle cdb, and is directed up, from vertex c to vertex d.
/// (Hence, the two triangles have rotated clockwise.)
/// </remarks>
internal void Unflip(ref Otri flipedge)
{
Otri botleft = default(Otri), botright = default(Otri);
Otri topleft = default(Otri), topright = default(Otri);
Otri top = default(Otri);
Otri botlcasing = default(Otri), botrcasing = default(Otri);
Otri toplcasing = default(Otri), toprcasing = default(Otri);
Osub botlsubseg = default(Osub), botrsubseg = default(Osub);
Osub toplsubseg = default(Osub), toprsubseg = default(Osub);
Vertex leftvertex, rightvertex, botvertex;
Vertex farvertex;
// Identify the vertices of the quadrilateral.
rightvertex = flipedge.Org();
leftvertex = flipedge.Dest();
botvertex = flipedge.Apex();
flipedge.Sym(ref top);
farvertex = top.Apex();
// Identify the casing of the quadrilateral.
top.Lprev(ref topleft);
topleft.Sym(ref toplcasing);
top.Lnext(ref topright);
topright.Sym(ref toprcasing);
flipedge.Lnext(ref botleft);
botleft.Sym(ref botlcasing);
flipedge.Lprev(ref botright);
botright.Sym(ref botrcasing);
// Rotate the quadrilateral one-quarter turn clockwise.
topleft.Bond(ref toprcasing);
botleft.Bond(ref toplcasing);
botright.Bond(ref botlcasing);
topright.Bond(ref botrcasing);
if (checksegments)
{
// Check for subsegments and rebond them to the quadrilateral.
topleft.Pivot(ref toplsubseg);
botleft.Pivot(ref botlsubseg);
botright.Pivot(ref botrsubseg);
topright.Pivot(ref toprsubseg);
if (toplsubseg.seg.hash == DUMMY)
{
botleft.SegDissolve(dummysub);
}
else
{
botleft.SegBond(ref toplsubseg);
}
if (botlsubseg.seg.hash == DUMMY)
{
botright.SegDissolve(dummysub);
}
else
{
botright.SegBond(ref botlsubseg);
}
if (botrsubseg.seg.hash == DUMMY)
{
topright.SegDissolve(dummysub);
}
else
{
topright.SegBond(ref botrsubseg);
}
if (toprsubseg.seg.hash == DUMMY)
{
topleft.SegDissolve(dummysub);
}
else
{
topleft.SegBond(ref toprsubseg);
}
}
// New vertex assignments for the rotated quadrilateral.
flipedge.SetOrg(botvertex);
flipedge.SetDest(farvertex);
flipedge.SetApex(leftvertex);
top.SetOrg(farvertex);
top.SetDest(botvertex);
top.SetApex(rightvertex);
}
bool RightOfHyperbola(ref Otri fronttri, Point newsite)
{
Vertex leftvertex, rightvertex;
double dxa, dya, dxb, dyb;
Statistic.HyperbolaCount++;
leftvertex = fronttri.Dest();
rightvertex = fronttri.Apex();
if ((leftvertex.y < rightvertex.y) ||
((leftvertex.y == rightvertex.y) &&
(leftvertex.x < rightvertex.x)))
{
if (newsite.x >= rightvertex.x)
{
return true;
}
}
else
{
if (newsite.x <= leftvertex.x)
{
return false;
}
}
dxa = leftvertex.x - newsite.x;
dya = leftvertex.y - newsite.y;
dxb = rightvertex.x - newsite.x;
dyb = rightvertex.y - newsite.y;
return dya * (dxb * dxb + dyb * dyb) > dyb * (dxa * dxa + dya * dya);
}
/// <summary>
/// Find the Delaunay triangulation of a polygon that has a certain "nice" shape.
/// This includes the polygons that result from deletion of a vertex or insertion
/// of a segment.
/// </summary>
/// <param name="firstedge">The primary edge of the first triangle.</param>
/// <param name="lastedge">The primary edge of the last triangle.</param>
/// <param name="edgecount">The number of sides of the polygon, including its
/// base.</param>
/// <param name="doflip">A flag, wether to perform the last flip.</param>
/// <param name="triflaws">A flag that determines whether the new triangles should
/// be tested for quality, and enqueued if they are bad.</param>
/// <remarks>
// This is a conceptually difficult routine. The starting assumption is
// that we have a polygon with n sides. n - 1 of these sides are currently
// represented as edges in the mesh. One side, called the "base", need not
// be.
//
// Inside the polygon is a structure I call a "fan", consisting of n - 1
// triangles that share a common origin. For each of these triangles, the
// edge opposite the origin is one of the sides of the polygon. The
// primary edge of each triangle is the edge directed from the origin to
// the destination; note that this is not the same edge that is a side of
// the polygon. 'firstedge' is the primary edge of the first triangle.
// From there, the triangles follow in counterclockwise order about the
// polygon, until 'lastedge', the primary edge of the last triangle.
// 'firstedge' and 'lastedge' are probably connected to other triangles
// beyond the extremes of the fan, but their identity is not important, as
// long as the fan remains connected to them.
//
// Imagine the polygon oriented so that its base is at the bottom. This
// puts 'firstedge' on the far right, and 'lastedge' on the far left.
// The right vertex of the base is the destination of 'firstedge', and the
// left vertex of the base is the apex of 'lastedge'.
//
// The challenge now is to find the right sequence of edge flips to
// transform the fan into a Delaunay triangulation of the polygon. Each
// edge flip effectively removes one triangle from the fan, committing it
// to the polygon. The resulting polygon has one fewer edge. If 'doflip'
// is set, the final flip will be performed, resulting in a fan of one
// (useless?) triangle. If 'doflip' is not set, the final flip is not
// performed, resulting in a fan of two triangles, and an unfinished
// triangular polygon that is not yet filled out with a single triangle.
// On completion of the routine, 'lastedge' is the last remaining triangle,
// or the leftmost of the last two.
//
// Although the flips are performed in the order described above, the
// decisions about what flips to perform are made in precisely the reverse
// order. The recursive triangulatepolygon() procedure makes a decision,
// uses up to two recursive calls to triangulate the "subproblems"
// (polygons with fewer edges), and then performs an edge flip.
//
// The "decision" it makes is which vertex of the polygon should be
// connected to the base. This decision is made by testing every possible
// vertex. Once the best vertex is found, the two edges that connect this
// vertex to the base become the bases for two smaller polygons. These
// are triangulated recursively. Unfortunately, this approach can take
// O(n^2) time not only in the worst case, but in many common cases. It's
// rarely a big deal for vertex deletion, where n is rarely larger than
// ten, but it could be a big deal for segment insertion, especially if
// there's a lot of long segments that each cut many triangles. I ought to
// code a faster algorithm some day.
/// </remarks>
private void TriangulatePolygon(Otri firstedge, Otri lastedge,
int edgecount, bool doflip, bool triflaws)
{
Otri testtri = default(Otri);
Otri besttri = default(Otri);
Otri tempedge = default(Otri);
Vertex leftbasevertex, rightbasevertex;
Vertex testvertex;
Vertex bestvertex;
int bestnumber = 1;
// Identify the base vertices.
leftbasevertex = lastedge.Apex();
rightbasevertex = firstedge.Dest();
// Find the best vertex to connect the base to.
firstedge.Onext(ref besttri);
bestvertex = besttri.Dest();
besttri.Copy(ref testtri);
for (int i = 2; i <= edgecount - 2; i++)
{
testtri.Onext();
testvertex = testtri.Dest();
// Is this a better vertex?
if (predicates.InCircle(leftbasevertex, rightbasevertex, bestvertex, testvertex) > 0.0)
{
testtri.Copy(ref besttri);
bestvertex = testvertex;
bestnumber = i;
}
}
if (bestnumber > 1)
{
// Recursively triangulate the smaller polygon on the right.
besttri.Oprev(ref tempedge);
TriangulatePolygon(firstedge, tempedge, bestnumber + 1, true, triflaws);
}
if (bestnumber < edgecount - 2)
{
// Recursively triangulate the smaller polygon on the left.
besttri.Sym(ref tempedge);
TriangulatePolygon(besttri, lastedge, edgecount - bestnumber, true, triflaws);
// Find 'besttri' again; it may have been lost to edge flips.
tempedge.Sym(ref besttri);
}
if (doflip)
{
// Do one final edge flip.
Flip(ref besttri);
if (triflaws)
{
// Check the quality of the newly committed triangle.
besttri.Sym(ref testtri);
qualityMesher.TestTriangle(ref testtri);
}
}
// Return the base triangle.
besttri.Copy(ref lastedge);
}
void Check4DeadEvent(ref Otri checktri, SweepEvent[] eventheap, ref int heapsize)
{
SweepEvent deadevent;
SweepEventVertex eventvertex;
int eventnum = -1;
eventvertex = checktri.Org() as SweepEventVertex;
if (eventvertex != null)
{
deadevent = eventvertex.evt;
eventnum = deadevent.heapposition;
HeapDelete(eventheap, heapsize, eventnum);
heapsize--;
checktri.SetOrg(null);
}
}
/// <summary>
/// Create a new triangle with orientation zero.
/// </summary>
/// <param name="newotri">Reference to the new triangle.</param>
internal void MakeTriangle(ref Otri newotri)
{
Triangle tri = triangles.Get();
//tri.id = tri.hash;
tri.subsegs[0].seg = dummysub;
tri.subsegs[1].seg = dummysub;
tri.subsegs[2].seg = dummysub;
tri.neighbors[0].tri = dummytri;
tri.neighbors[1].tri = dummytri;
tri.neighbors[2].tri = dummytri;
newotri.tri = tri;
newotri.orient = 0;
}
/// <summary>
/// Checks if smothing is possible for a given bad triangle.
/// </summary>
/// <param name="badotri"></param>
/// <param name="torg"></param>
/// <param name="tdest"></param>
/// <param name="tapex"></param>
/// <param name="newloc">The new location for the point, if somothing is possible.</param>
/// <returns>Returns 1, 2 or 3 if smoothing will work, 0 otherwise.</returns>
private int DoSmoothing(Otri badotri, Vertex torg, Vertex tdest, Vertex tapex,
ref double[] newloc)
{
int numpoints_p = 0;// keeps the number of points in a star of point p, q, r
int numpoints_q = 0;
int numpoints_r = 0;
//int i;
double[] possibilities = new double[6];//there can be more than one possibilities
int num_pos = 0; // number of possibilities
int flag1 = 0, flag2 = 0, flag3 = 0;
bool newLocFound = false;
//vertex v1, v2, v3; // for ccw test
//double p1[2], p2[2], p3[2];
//double temp[2];
//********************* TRY TO RELOCATE POINT "p" ***************
// get the surrounding points of p, so this gives us the triangles
numpoints_p = GetStarPoints(badotri, torg, tdest, tapex, 1, ref points_p);
// check if the points in counterclockwise order
// p1[0] = points_p[0]; p1[1] = points_p[1];
// p2[0] = points_p[2]; p2[1] = points_p[3];
// p3[0] = points_p[4]; p3[1] = points_p[5];
// v1 = (vertex)p1; v2 = (vertex)p2; v3 = (vertex)p3;
// if(counterclockwise(m,b,v1,v2,v3) < 0){
// // reverse the order to ccw
// for(i = 0; i < numpoints_p/2; i++){
// temp[0] = points_p[2*i];
// temp[1] = points_p[2*i+1];
// points_p[2*i] = points_p[2*(numpoints_p-1)-2*i];
// points_p[2*i+1] = points_p[2*(numpoints_p-1)+1-2*i];
// points_p[2*(numpoints_p-1)-2*i] = temp[0];
// points_p[2*(numpoints_p-1)+1-2*i] = temp[1];
// }
// }
// m.counterclockcount--;
// INTERSECTION OF PETALS
// first check whether the star angles are appropriate for relocation
if (torg.type == VertexType.FreeVertex && numpoints_p != 0 && ValidPolygonAngles(numpoints_p, points_p))
{
//newLocFound = getPetalIntersection(m, b, numpoints_p, points_p, newloc);
//newLocFound = getPetalIntersectionBruteForce(m, b,numpoints_p, points_p, newloc,torg[0],torg[1]);
if (behavior.MaxAngle == 0.0)
{
newLocFound = GetWedgeIntersectionWithoutMaxAngle(numpoints_p, points_p, ref newloc);
}
else
{
newLocFound = GetWedgeIntersection(numpoints_p, points_p, ref newloc);
}
//printf("call petal intersection for p\n");
// make sure the relocated point is a free vertex
if (newLocFound)
{
possibilities[0] = newloc[0];// something found
possibilities[1] = newloc[1];
num_pos++;// increase the number of possibilities
flag1 = 1;
}
}
//********************* TRY TO RELOCATE POINT "q" ***************
// get the surrounding points of q, so this gives us the triangles
numpoints_q = GetStarPoints(badotri, torg, tdest, tapex, 2, ref points_q);
// // check if the points in counterclockwise order
// v1[0] = points_q[0]; v1[1] = points_q[1];
// v2[0] = points_q[2]; v2[1] = points_q[3];
// v3[0] = points_q[4]; v3[1] = points_q[5];
// if(counterclockwise(m,b,v1,v2,v3) < 0){
// // reverse the order to ccw
// for(i = 0; i < numpoints_q/2; i++){
// temp[0] = points_q[2*i];
// temp[1] = points_q[2*i+1];
// points_q[2*i] = points_q[2*(numpoints_q-1)-2*i];
// points_q[2*i+1] = points_q[2*(numpoints_q-1)+1-2*i];
// points_q[2*(numpoints_q-1)-2*i] = temp[0];
// points_q[2*(numpoints_q-1)+1-2*i] = temp[1];
// }
// }
// m.counterclockcount--;
// INTERSECTION OF PETALS
// first check whether the star angles are appropriate for relocation
if (tdest.type == VertexType.FreeVertex && numpoints_q != 0 && ValidPolygonAngles(numpoints_q, points_q))
{
//newLocFound = getPetalIntersection(m, b,numpoints_q, points_q, newloc);
//newLocFound = getPetalIntersectionBruteForce(m, b,numpoints_q, points_q, newloc,tapex[0],tapex[1]);
if (behavior.MaxAngle == 0.0)
{
newLocFound = GetWedgeIntersectionWithoutMaxAngle(numpoints_q, points_q, ref newloc);
}
else
{
newLocFound = GetWedgeIntersection(numpoints_q, points_q, ref newloc);
}
//printf("call petal intersection for q\n");
// make sure the relocated point is a free vertex
if (newLocFound)
{
possibilities[2] = newloc[0];// something found
possibilities[3] = newloc[1];
num_pos++;// increase the number of possibilities
flag2 = 2;
}
}
//********************* TRY TO RELOCATE POINT "q" ***************
// get the surrounding points of r, so this gives us the triangles
numpoints_r = GetStarPoints(badotri, torg, tdest, tapex, 3, ref points_r);
// check if the points in counterclockwise order
// v1[0] = points_r[0]; v1[1] = points_r[1];
// v2[0] = points_r[2]; v2[1] = points_r[3];
// v3[0] = points_r[4]; v3[1] = points_r[5];
// if(counterclockwise(m,b,v1,v2,v3) < 0){
// // reverse the order to ccw
// for(i = 0; i < numpoints_r/2; i++){
// temp[0] = points_r[2*i];
// temp[1] = points_r[2*i+1];
// points_r[2*i] = points_r[2*(numpoints_r-1)-2*i];
// points_r[2*i+1] = points_r[2*(numpoints_r-1)+1-2*i];
// points_r[2*(numpoints_r-1)-2*i] = temp[0];
// points_r[2*(numpoints_r-1)+1-2*i] = temp[1];
// }
// }
// m.counterclockcount--;
// INTERSECTION OF PETALS
// first check whether the star angles are appropriate for relocation
if (tapex.type == VertexType.FreeVertex && numpoints_r != 0 && ValidPolygonAngles(numpoints_r, points_r))
{
//newLocFound = getPetalIntersection(m, b,numpoints_r, points_r, newloc);
//newLocFound = getPetalIntersectionBruteForce(m, b,numpoints_r, points_r, newloc,tdest[0],tdest[1]);
if (behavior.MaxAngle == 0.0)
{
newLocFound = GetWedgeIntersectionWithoutMaxAngle(numpoints_r, points_r, ref newloc);
}
else
{
newLocFound = GetWedgeIntersection(numpoints_r, points_r, ref newloc);
}
//printf("call petal intersection for r\n");
// make sure the relocated point is a free vertex
if (newLocFound)
{
possibilities[4] = newloc[0];// something found
possibilities[5] = newloc[1];
num_pos++;// increase the number of possibilities
flag3 = 3;
}
}
//printf("numpossibilities %d\n",num_pos);
//////////// AFTER FINISH CHECKING EVERY POSSIBILITY, CHOOSE ANY OF THE AVAILABLE ONE //////////////////////
if (num_pos > 0)
{
if (flag1 > 0)
{ // suggest to relocate origin
newloc[0] = possibilities[0];
newloc[1] = possibilities[1];
return flag1;
}
else
{
if (flag2 > 0)
{ // suggest to relocate apex
newloc[0] = possibilities[2];
newloc[1] = possibilities[3];
return flag2;
}
else
{// suggest to relocate destination
if (flag3 > 0)
{
newloc[0] = possibilities[4];
newloc[1] = possibilities[5];
return flag3;
}
}
}
}
return 0;// could not find any good relocation
}
/// <summary>
/// Find a triangle or edge containing a given point.
/// </summary>
/// <param name="searchpoint">The point to locate.</param>
/// <param name="searchtri">The triangle to start the search at.</param>
/// <param name="stopatsubsegment"> If 'stopatsubsegment' is set, the search
/// will stop if it tries to walk through a subsegment, and will return OUTSIDE.</param>
/// <returns>Location information.</returns>
/// <remarks>
/// Begins its search from 'searchtri'. It is important that 'searchtri'
/// be a handle with the property that 'searchpoint' is strictly to the left
/// of the edge denoted by 'searchtri', or is collinear with that edge and
/// does not intersect that edge. (In particular, 'searchpoint' should not
/// be the origin or destination of that edge.)
///
/// These conditions are imposed because preciselocate() is normally used in
/// one of two situations:
///
/// (1) To try to find the location to insert a new point. Normally, we
/// know an edge that the point is strictly to the left of. In the
/// incremental Delaunay algorithm, that edge is a bounding box edge.
/// In Ruppert's Delaunay refinement algorithm for quality meshing,
/// that edge is the shortest edge of the triangle whose circumcenter
/// is being inserted.
///
/// (2) To try to find an existing point. In this case, any edge on the
/// convex hull is a good starting edge. You must screen out the
/// possibility that the vertex sought is an endpoint of the starting
/// edge before you call preciselocate().
///
/// On completion, 'searchtri' is a triangle that contains 'searchpoint'.
///
/// This implementation differs from that given by Guibas and Stolfi. It
/// walks from triangle to triangle, crossing an edge only if 'searchpoint'
/// is on the other side of the line containing that edge. After entering
/// a triangle, there are two edges by which one can leave that triangle.
/// If both edges are valid ('searchpoint' is on the other side of both
/// edges), one of the two is chosen by drawing a line perpendicular to
/// the entry edge (whose endpoints are 'forg' and 'fdest') passing through
/// 'fapex'. Depending on which side of this perpendicular 'searchpoint'
/// falls on, an exit edge is chosen.
///
/// This implementation is empirically faster than the Guibas and Stolfi
/// point location routine (which I originally used), which tends to spiral
/// in toward its target.
///
/// Returns ONVERTEX if the point lies on an existing vertex. 'searchtri'
/// is a handle whose origin is the existing vertex.
///
/// Returns ONEDGE if the point lies on a mesh edge. 'searchtri' is a
/// handle whose primary edge is the edge on which the point lies.
///
/// Returns INTRIANGLE if the point lies strictly within a triangle.
/// 'searchtri' is a handle on the triangle that contains the point.
///
/// Returns OUTSIDE if the point lies outside the mesh. 'searchtri' is a
/// handle whose primary edge the point is to the right of. This might
/// occur when the circumcenter of a triangle falls just slightly outside
/// the mesh due to floating-point roundoff error. It also occurs when
/// seeking a hole or region point that a foolish user has placed outside
/// the mesh.
///
/// WARNING: This routine is designed for convex triangulations, and will
/// not generally work after the holes and concavities have been carved.
/// However, it can still be used to find the circumcenter of a triangle, as
/// long as the search is begun from the triangle in question.</remarks>
public LocateResult PreciseLocate(Point searchpoint, ref Otri searchtri,
bool stopatsubsegment)
{
Otri backtracktri = default(Otri);
Osub checkedge = default(Osub);
Vertex forg, fdest, fapex;
double orgorient, destorient;
bool moveleft;
// Where are we?
forg = searchtri.Org();
fdest = searchtri.Dest();
fapex = searchtri.Apex();
while (true)
{
// Check whether the apex is the point we seek.
if ((fapex.x == searchpoint.x) && (fapex.y == searchpoint.y))
{
searchtri.Lprev();
return LocateResult.OnVertex;
}
// Does the point lie on the other side of the line defined by the
// triangle edge opposite the triangle's destination?
destorient = predicates.CounterClockwise(forg, fapex, searchpoint);
// Does the point lie on the other side of the line defined by the
// triangle edge opposite the triangle's origin?
orgorient = predicates.CounterClockwise(fapex, fdest, searchpoint);
if (destorient > 0.0)
{
if (orgorient > 0.0)
{
// Move left if the inner product of (fapex - searchpoint) and
// (fdest - forg) is positive. This is equivalent to drawing
// a line perpendicular to the line (forg, fdest) and passing
// through 'fapex', and determining which side of this line
// 'searchpoint' falls on.
moveleft = (fapex.x - searchpoint.x) * (fdest.x - forg.x) +
(fapex.y - searchpoint.y) * (fdest.y - forg.y) > 0.0;
}
else
{
moveleft = true;
}
}
else
{
if (orgorient > 0.0)
{
moveleft = false;
}
else
{
// The point we seek must be on the boundary of or inside this
// triangle.
if (destorient == 0.0)
{
searchtri.Lprev();
return LocateResult.OnEdge;
}
if (orgorient == 0.0)
{
searchtri.Lnext();
return LocateResult.OnEdge;
}
return LocateResult.InTriangle;
}
}
// Move to another triangle. Leave a trace 'backtracktri' in case
// floating-point roundoff or some such bogey causes us to walk
// off a boundary of the triangulation.
if (moveleft)
{
searchtri.Lprev(ref backtracktri);
fdest = fapex;
}
else
{
searchtri.Lnext(ref backtracktri);
forg = fapex;
}
backtracktri.Sym(ref searchtri);
if (mesh.checksegments && stopatsubsegment)
{
// Check for walking through a subsegment.
backtracktri.Pivot(ref checkedge);
if (checkedge.seg.hash != Mesh.DUMMY)
{
// Go back to the last triangle.
backtracktri.Copy(ref searchtri);
return LocateResult.Outside;
}
}
// Check for walking right out of the triangulation.
if (searchtri.tri.id == Mesh.DUMMY)
{
// Go back to the last triangle.
backtracktri.Copy(ref searchtri);
return LocateResult.Outside;
}
fapex = searchtri.Apex();
}
}
/// <summary>
/// Gets a neighbours vertex.
/// </summary>
/// <param name="badotri"></param>
/// <param name="first_x"></param>
/// <param name="first_y"></param>
/// <param name="second_x"></param>
/// <param name="second_y"></param>
/// <param name="thirdpoint">Neighbor's third vertex incident to given edge.</param>
/// <param name="neighotri">Pointer for the neighbor triangle.</param>
/// <returns>Returns true if vertex was found.</returns>
private bool GetNeighborsVertex(Otri badotri,
double first_x, double first_y,
double second_x, double second_y,
ref double[] thirdpoint, ref Otri neighotri)
{
Otri neighbor = default(Otri); // keeps the neighbor triangles
bool notFound = false; // boolean variable if we can find that neighbor or not
// for keeping the vertices of the neighbor triangle
Vertex neighborvertex_1 = null;
Vertex neighborvertex_2 = null;
Vertex neighborvertex_3 = null;
// used for finding neighbor triangle
int firstVertexMatched = 0, secondVertexMatched = 0; // to find the correct neighbor
//triangle ptr; // Temporary variable used by sym()
//int i; // index variable
// find neighbors
// Check each of the triangle's three neighbors to find the correct one
for (badotri.orient = 0; badotri.orient < 3; badotri.orient++)
{
// Find the neighbor.
badotri.Sym(ref neighbor);
// check if it is the one we are looking for by checking the corners
// first check if the neighbor is nonexistent, since it can be on the border
if (neighbor.tri.id != Mesh.DUMMY)
{
// then check if two wanted corners are also in this triangle
// take the vertices of the candidate neighbor
neighborvertex_1 = neighbor.Org();
neighborvertex_2 = neighbor.Dest();
neighborvertex_3 = neighbor.Apex();
// check if it is really a triangle
if ((neighborvertex_1.x == neighborvertex_2.x && neighborvertex_1.y == neighborvertex_2.y)
|| (neighborvertex_2.x == neighborvertex_3.x && neighborvertex_2.y == neighborvertex_3.y)
|| (neighborvertex_1.x == neighborvertex_3.x && neighborvertex_1.y == neighborvertex_3.y))
{
//printf("Two vertices are the same!!!!!!!\n");
}
else
{
// begin searching for the correct neighbor triangle
firstVertexMatched = 0;
if ((Math.Abs(first_x - neighborvertex_1.x) < EPS) &&
(Math.Abs(first_y - neighborvertex_1.y) < EPS))
{
firstVertexMatched = 11; // neighbor's 1st vertex is matched to first vertex
}
else if ((Math.Abs(first_x - neighborvertex_2.x) < EPS) &&
(Math.Abs(first_y - neighborvertex_2.y) < EPS))
{
firstVertexMatched = 12; // neighbor's 2nd vertex is matched to first vertex
}
else if ((Math.Abs(first_x - neighborvertex_3.x) < EPS) &&
(Math.Abs(first_y - neighborvertex_3.y) < EPS))
{
firstVertexMatched = 13; // neighbor's 3rd vertex is matched to first vertex
}/*else{
// none of them matched
} // end of first vertex matching */
secondVertexMatched = 0;
if ((Math.Abs(second_x - neighborvertex_1.x) < EPS) &&
(Math.Abs(second_y - neighborvertex_1.y) < EPS))
{
secondVertexMatched = 21; // neighbor's 1st vertex is matched to second vertex
}
else if ((Math.Abs(second_x - neighborvertex_2.x) < EPS) &&
(Math.Abs(second_y - neighborvertex_2.y) < EPS))
{
secondVertexMatched = 22; // neighbor's 2nd vertex is matched to second vertex
}
else if ((Math.Abs(second_x - neighborvertex_3.x) < EPS) &&
(Math.Abs(second_y - neighborvertex_3.y) < EPS))
{
secondVertexMatched = 23; // neighbor's 3rd vertex is matched to second vertex
}/*else{
// none of them matched
} // end of second vertex matching*/
}
}// if neighbor exists or not
if (((firstVertexMatched == 11) && (secondVertexMatched == 22 || secondVertexMatched == 23))
|| ((firstVertexMatched == 12) && (secondVertexMatched == 21 || secondVertexMatched == 23))
|| ((firstVertexMatched == 13) && (secondVertexMatched == 21 || secondVertexMatched == 22)))
break;
}// end of for loop over all orientations
switch (firstVertexMatched)
{
case 0:
notFound = true;
break;
case 11:
if (secondVertexMatched == 22)
{
thirdpoint[0] = neighborvertex_3.x;
thirdpoint[1] = neighborvertex_3.y;
}
else if (secondVertexMatched == 23)
{
thirdpoint[0] = neighborvertex_2.x;
thirdpoint[1] = neighborvertex_2.y;
}
else { notFound = true; }
break;
case 12:
if (secondVertexMatched == 21)
{
thirdpoint[0] = neighborvertex_3.x;
thirdpoint[1] = neighborvertex_3.y;
}
else if (secondVertexMatched == 23)
{
thirdpoint[0] = neighborvertex_1.x;
thirdpoint[1] = neighborvertex_1.y;
}
else { notFound = true; }
break;
case 13:
if (secondVertexMatched == 21)
{
thirdpoint[0] = neighborvertex_2.x;
thirdpoint[1] = neighborvertex_2.y;
}
else if (secondVertexMatched == 22)
{
thirdpoint[0] = neighborvertex_1.x;
thirdpoint[1] = neighborvertex_1.y;
}
else { notFound = true; }
break;
default:
if (secondVertexMatched == 0) { notFound = true; }
break;
}
// pointer of the neighbor triangle
neighotri = neighbor;
return notFound;
}
/// <summary>
/// Suggest the given triangle as a starting triangle for point location.
/// </summary>
/// <param name="otri"></param>
public void Update(ref Otri otri)
{
otri.Copy(ref recenttri);
}
/// <summary>
/// Find the previous edge (clockwise) of a triangle. [lprev(abc) -> cab]
/// </summary>
public void Lprev(ref Otri ot)
{
ot.tri = tri;
ot.orient = minus1Mod3[orient];
}
/// <summary>
/// Merge two adjacent Delaunay triangulations into a single Delaunay triangulation.
/// </summary>
/// <param name="farleft">Bounding triangles of the left triangulation.</param>
/// <param name="innerleft">Bounding triangles of the left triangulation.</param>
/// <param name="innerright">Bounding triangles of the right triangulation.</param>
/// <param name="farright">Bounding triangles of the right triangulation.</param>
/// <param name="axis"></param>
/// <remarks>
/// This is similar to the algorithm given by Guibas and Stolfi, but uses
/// a triangle-based, rather than edge-based, data structure.
///
/// The algorithm walks up the gap between the two triangulations, knitting
/// them together. As they are merged, some of their bounding triangles
/// are converted into real triangles of the triangulation. The procedure
/// pulls each hull's bounding triangles apart, then knits them together
/// like the teeth of two gears. The Delaunay property determines, at each
/// step, whether the next "tooth" is a bounding triangle of the left hull
/// or the right. When a bounding triangle becomes real, its apex is
/// changed from NULL to a real vertex.
///
/// Only two new triangles need to be allocated. These become new bounding
/// triangles at the top and bottom of the seam. They are used to connect
/// the remaining bounding triangles (those that have not been converted
/// into real triangles) into a single fan.
///
/// On entry, 'farleft' and 'innerleft' are bounding triangles of the left
/// triangulation. The origin of 'farleft' is the leftmost vertex, and
/// the destination of 'innerleft' is the rightmost vertex of the
/// triangulation. Similarly, 'innerright' and 'farright' are bounding
/// triangles of the right triangulation. The origin of 'innerright' and
/// destination of 'farright' are the leftmost and rightmost vertices.
///
/// On completion, the origin of 'farleft' is the leftmost vertex of the
/// merged triangulation, and the destination of 'farright' is the rightmost
/// vertex.
/// </remarks>
void MergeHulls(ref Otri farleft, ref Otri innerleft, ref Otri innerright,
ref Otri farright, int axis)
{
Otri leftcand = default(Otri), rightcand = default(Otri);
Otri nextedge = default(Otri);
Otri sidecasing = default(Otri), topcasing = default(Otri), outercasing = default(Otri);
Otri checkedge = default(Otri);
Otri baseedge = default(Otri);
Vertex innerleftdest;
Vertex innerrightorg;
Vertex innerleftapex, innerrightapex;
Vertex farleftpt, farrightpt;
Vertex farleftapex, farrightapex;
Vertex lowerleft, lowerright;
Vertex upperleft, upperright;
Vertex nextapex;
Vertex checkvertex;
bool changemade;
bool badedge;
bool leftfinished, rightfinished;
innerleftdest = innerleft.Dest();
innerleftapex = innerleft.Apex();
innerrightorg = innerright.Org();
innerrightapex = innerright.Apex();
// Special treatment for horizontal cuts.
if (UseDwyer && (axis == 1))
{
farleftpt = farleft.Org();
farleftapex = farleft.Apex();
farrightpt = farright.Dest();
farrightapex = farright.Apex();
// The pointers to the extremal vertices are shifted to point to the
// topmost and bottommost vertex of each hull, rather than the
// leftmost and rightmost vertices.
while (farleftapex.y < farleftpt.y)
{
farleft.Lnext();
farleft.Sym();
farleftpt = farleftapex;
farleftapex = farleft.Apex();
}
innerleft.Sym(ref checkedge);
checkvertex = checkedge.Apex();
while (checkvertex.y > innerleftdest.y)
{
checkedge.Lnext(ref innerleft);
innerleftapex = innerleftdest;
innerleftdest = checkvertex;
innerleft.Sym(ref checkedge);
checkvertex = checkedge.Apex();
}
while (innerrightapex.y < innerrightorg.y)
{
innerright.Lnext();
innerright.Sym();
innerrightorg = innerrightapex;
innerrightapex = innerright.Apex();
}
farright.Sym(ref checkedge);
checkvertex = checkedge.Apex();
while (checkvertex.y > farrightpt.y)
{
checkedge.Lnext(ref farright);
farrightapex = farrightpt;
farrightpt = checkvertex;
farright.Sym(ref checkedge);
checkvertex = checkedge.Apex();
}
}
// Find a line tangent to and below both hulls.
do
{
changemade = false;
// Make innerleftdest the "bottommost" vertex of the left hull.
if (predicates.CounterClockwise(innerleftdest, innerleftapex, innerrightorg) > 0.0)
{
innerleft.Lprev();
innerleft.Sym();
innerleftdest = innerleftapex;
innerleftapex = innerleft.Apex();
changemade = true;
}
// Make innerrightorg the "bottommost" vertex of the right hull.
if (predicates.CounterClockwise(innerrightapex, innerrightorg, innerleftdest) > 0.0)
{
innerright.Lnext();
innerright.Sym();
innerrightorg = innerrightapex;
innerrightapex = innerright.Apex();
changemade = true;
}
} while (changemade);
// Find the two candidates to be the next "gear tooth."
innerleft.Sym(ref leftcand);
innerright.Sym(ref rightcand);
// Create the bottom new bounding triangle.
mesh.MakeTriangle(ref baseedge);
// Connect it to the bounding boxes of the left and right triangulations.
baseedge.Bond(ref innerleft);
baseedge.Lnext();
baseedge.Bond(ref innerright);
baseedge.Lnext();
baseedge.SetOrg(innerrightorg);
baseedge.SetDest(innerleftdest);
// Apex is intentionally left NULL.
// Fix the extreme triangles if necessary.
farleftpt = farleft.Org();
if (innerleftdest == farleftpt)
{
baseedge.Lnext(ref farleft);
}
farrightpt = farright.Dest();
if (innerrightorg == farrightpt)
{
baseedge.Lprev(ref farright);
}
// The vertices of the current knitting edge.
lowerleft = innerleftdest;
lowerright = innerrightorg;
// The candidate vertices for knitting.
upperleft = leftcand.Apex();
upperright = rightcand.Apex();
// Walk up the gap between the two triangulations, knitting them together.
while (true)
{
// Have we reached the top? (This isn't quite the right question,
// because even though the left triangulation might seem finished now,
// moving up on the right triangulation might reveal a new vertex of
// the left triangulation. And vice-versa.)
leftfinished = predicates.CounterClockwise(upperleft, lowerleft, lowerright) <= 0.0;
rightfinished = predicates.CounterClockwise(upperright, lowerleft, lowerright) <= 0.0;
if (leftfinished && rightfinished)
{
// Create the top new bounding triangle.
mesh.MakeTriangle(ref nextedge);
nextedge.SetOrg(lowerleft);
nextedge.SetDest(lowerright);
// Apex is intentionally left NULL.
// Connect it to the bounding boxes of the two triangulations.
nextedge.Bond(ref baseedge);
nextedge.Lnext();
nextedge.Bond(ref rightcand);
nextedge.Lnext();
nextedge.Bond(ref leftcand);
// Special treatment for horizontal cuts.
if (UseDwyer && (axis == 1))
{
farleftpt = farleft.Org();
farleftapex = farleft.Apex();
farrightpt = farright.Dest();
farrightapex = farright.Apex();
farleft.Sym(ref checkedge);
checkvertex = checkedge.Apex();
// The pointers to the extremal vertices are restored to the
// leftmost and rightmost vertices (rather than topmost and
// bottommost).
while (checkvertex.x < farleftpt.x)
{
checkedge.Lprev(ref farleft);
farleftapex = farleftpt;
farleftpt = checkvertex;
farleft.Sym(ref checkedge);
checkvertex = checkedge.Apex();
}
while (farrightapex.x > farrightpt.x)
{
farright.Lprev();
farright.Sym();
farrightpt = farrightapex;
farrightapex = farright.Apex();
}
}
return;
}
// Consider eliminating edges from the left triangulation.
if (!leftfinished)
{
// What vertex would be exposed if an edge were deleted?
leftcand.Lprev(ref nextedge);
nextedge.Sym();
nextapex = nextedge.Apex();
// If nextapex is NULL, then no vertex would be exposed; the
// triangulation would have been eaten right through.
if (nextapex != null)
{
// Check whether the edge is Delaunay.
badedge = predicates.InCircle(lowerleft, lowerright, upperleft, nextapex) > 0.0;
while (badedge)
{
// Eliminate the edge with an edge flip. As a result, the
// left triangulation will have one more boundary triangle.
nextedge.Lnext();
nextedge.Sym(ref topcasing);
nextedge.Lnext();
nextedge.Sym(ref sidecasing);
nextedge.Bond(ref topcasing);
leftcand.Bond(ref sidecasing);
leftcand.Lnext();
leftcand.Sym(ref outercasing);
nextedge.Lprev();
nextedge.Bond(ref outercasing);
// Correct the vertices to reflect the edge flip.
leftcand.SetOrg(lowerleft);
leftcand.SetDest(null);
leftcand.SetApex(nextapex);
nextedge.SetOrg(null);
nextedge.SetDest(upperleft);
nextedge.SetApex(nextapex);
// Consider the newly exposed vertex.
upperleft = nextapex;
// What vertex would be exposed if another edge were deleted?
sidecasing.Copy(ref nextedge);
nextapex = nextedge.Apex();
if (nextapex != null)
{
// Check whether the edge is Delaunay.
badedge = predicates.InCircle(lowerleft, lowerright, upperleft, nextapex) > 0.0;
}
else
{
// Avoid eating right through the triangulation.
badedge = false;
}
}
}
}
// Consider eliminating edges from the right triangulation.
if (!rightfinished)
{
// What vertex would be exposed if an edge were deleted?
rightcand.Lnext(ref nextedge);
nextedge.Sym();
nextapex = nextedge.Apex();
// If nextapex is NULL, then no vertex would be exposed; the
// triangulation would have been eaten right through.
if (nextapex != null)
{
// Check whether the edge is Delaunay.
badedge = predicates.InCircle(lowerleft, lowerright, upperright, nextapex) > 0.0;
while (badedge)
{
// Eliminate the edge with an edge flip. As a result, the
// right triangulation will have one more boundary triangle.
nextedge.Lprev();
nextedge.Sym(ref topcasing);
nextedge.Lprev();
nextedge.Sym(ref sidecasing);
nextedge.Bond(ref topcasing);
rightcand.Bond(ref sidecasing);
rightcand.Lprev();
rightcand.Sym(ref outercasing);
nextedge.Lnext();
nextedge.Bond(ref outercasing);
// Correct the vertices to reflect the edge flip.
rightcand.SetOrg(null);
rightcand.SetDest(lowerright);
rightcand.SetApex(nextapex);
nextedge.SetOrg(upperright);
nextedge.SetDest(null);
nextedge.SetApex(nextapex);
// Consider the newly exposed vertex.
upperright = nextapex;
// What vertex would be exposed if another edge were deleted?
sidecasing.Copy(ref nextedge);
nextapex = nextedge.Apex();
if (nextapex != null)
{
// Check whether the edge is Delaunay.
badedge = predicates.InCircle(lowerleft, lowerright, upperright, nextapex) > 0.0;
}
else
{
// Avoid eating right through the triangulation.
badedge = false;
}
}
}
}
if (leftfinished || (!rightfinished &&
(predicates.InCircle(upperleft, lowerleft, lowerright, upperright) > 0.0)))
{
// Knit the triangulations, adding an edge from 'lowerleft'
// to 'upperright'.
baseedge.Bond(ref rightcand);
rightcand.Lprev(ref baseedge);
baseedge.SetDest(lowerleft);
lowerright = upperright;
baseedge.Sym(ref rightcand);
upperright = rightcand.Apex();
}
else
{
// Knit the triangulations, adding an edge from 'upperleft'
// to 'lowerright'.
baseedge.Bond(ref leftcand);
leftcand.Lnext(ref baseedge);
baseedge.SetOrg(lowerright);
lowerleft = upperleft;
baseedge.Sym(ref leftcand);
upperleft = leftcand.Apex();
}
}
}
/// <summary>
/// Copy an oriented triangle.
/// </summary>
public void Copy(ref Otri ot)
{
ot.tri = tri;
ot.orient = orient;
}
/// <summary>
/// Finds the star of a given point.
/// </summary>
/// <param name="badotri"></param>
/// <param name="p"></param>
/// <param name="q"></param>
/// <param name="r"></param>
/// <param name="whichPoint"></param>
/// <param name="points">List of points on the star of the given point.</param>
/// <returns>Number of points on the star of the given point.</returns>
private int GetStarPoints(Otri badotri, Vertex p, Vertex q, Vertex r,
int whichPoint, ref double[] points)
{
Otri neighotri = default(Otri); // for return value of the function
Otri tempotri; // for temporary usage
double first_x = 0, first_y = 0; // keeps the first point to be considered
double second_x = 0, second_y = 0; // for determining the edge we will begin
double third_x = 0, third_y = 0; // termination
double[] returnPoint = new double[2]; // for keeping the returned point
int numvertices = 0; // for keeping number of surrounding vertices
// first determine which point to be used to find its neighbor triangles
switch (whichPoint)
{
case 1:
first_x = p.x; // point at the center
first_y = p.y;
second_x = r.x; // second vertex of first edge to consider
second_y = r.y;
third_x = q.x; // for terminating the search
third_y = q.y;
break;
case 2:
first_x = q.x; // point at the center
first_y = q.y;
second_x = p.x; // second vertex of first edge to consider
second_y = p.y;
third_x = r.x; // for terminating the search
third_y = r.y;
break;
case 3:
first_x = r.x; // point at the center
first_y = r.y;
second_x = q.x; // second vertex of first edge to consider
second_y = q.y;
third_x = p.x; // for terminating the search
third_y = p.y;
break;
}
tempotri = badotri;
// add first point as the end of first edge
points[numvertices] = second_x;
numvertices++;
points[numvertices] = second_y;
numvertices++;
// assign as dummy value
returnPoint[0] = second_x; returnPoint[1] = second_y;
// until we reach the third point of the beginning triangle
do
{
// find the neighbor's third point where it is incident to given edge
if (!GetNeighborsVertex(tempotri, first_x, first_y, second_x, second_y, ref returnPoint, ref neighotri))
{
// go to next triangle
tempotri = neighotri;
// now the second point is the neighbor's third vertex
second_x = returnPoint[0];
second_y = returnPoint[1];
// add a new point to the list of surrounding points
points[numvertices] = returnPoint[0];
numvertices++;
points[numvertices] = returnPoint[1];
numvertices++;
}
else
{
numvertices = 0;
break;
}
} while (!((Math.Abs(returnPoint[0] - third_x) <= EPS) &&
(Math.Abs(returnPoint[1] - third_y) <= EPS)));
return numvertices / 2;
}
/// <summary>
/// Recursively form a Delaunay triangulation by the divide-and-conquer method.
/// </summary>
/// <param name="left"></param>
/// <param name="right"></param>
/// <param name="axis"></param>
/// <param name="farleft"></param>
/// <param name="farright"></param>
/// <remarks>
/// Recursively breaks down the problem into smaller pieces, which are
/// knitted together by mergehulls(). The base cases (problems of two or
/// three vertices) are handled specially here.
///
/// On completion, 'farleft' and 'farright' are bounding triangles such that
/// the origin of 'farleft' is the leftmost vertex (breaking ties by
/// choosing the highest leftmost vertex), and the destination of
/// 'farright' is the rightmost vertex (breaking ties by choosing the
/// lowest rightmost vertex).
/// </remarks>
void DivconqRecurse(int left, int right, int axis,
ref Otri farleft, ref Otri farright)
{
Otri midtri = default(Otri);
Otri tri1 = default(Otri);
Otri tri2 = default(Otri);
Otri tri3 = default(Otri);
Otri innerleft = default(Otri), innerright = default(Otri);
double area;
int vertices = right - left + 1;
int divider;
if (vertices == 2)
{
// The triangulation of two vertices is an edge. An edge is
// represented by two bounding triangles.
mesh.MakeTriangle(ref farleft);
farleft.SetOrg(sortarray[left]);
farleft.SetDest(sortarray[left + 1]);
// The apex is intentionally left NULL.
mesh.MakeTriangle(ref farright);
farright.SetOrg(sortarray[left + 1]);
farright.SetDest(sortarray[left]);
// The apex is intentionally left NULL.
farleft.Bond(ref farright);
farleft.Lprev();
farright.Lnext();
farleft.Bond(ref farright);
farleft.Lprev();
farright.Lnext();
farleft.Bond(ref farright);
// Ensure that the origin of 'farleft' is sortarray[0].
farright.Lprev(ref farleft);
return;
}
else if (vertices == 3)
{
// The triangulation of three vertices is either a triangle (with
// three bounding triangles) or two edges (with four bounding
// triangles). In either case, four triangles are created.
mesh.MakeTriangle(ref midtri);
mesh.MakeTriangle(ref tri1);
mesh.MakeTriangle(ref tri2);
mesh.MakeTriangle(ref tri3);
area = predicates.CounterClockwise(sortarray[left], sortarray[left + 1], sortarray[left + 2]);
if (area == 0.0)
{
// Three collinear vertices; the triangulation is two edges.
midtri.SetOrg(sortarray[left]);
midtri.SetDest(sortarray[left + 1]);
tri1.SetOrg(sortarray[left + 1]);
tri1.SetDest(sortarray[left]);
tri2.SetOrg(sortarray[left + 2]);
tri2.SetDest(sortarray[left + 1]);
tri3.SetOrg(sortarray[left + 1]);
tri3.SetDest(sortarray[left + 2]);
// All apices are intentionally left NULL.
midtri.Bond(ref tri1);
tri2.Bond(ref tri3);
midtri.Lnext();
tri1.Lprev();
tri2.Lnext();
tri3.Lprev();
midtri.Bond(ref tri3);
tri1.Bond(ref tri2);
midtri.Lnext();
tri1.Lprev();
tri2.Lnext();
tri3.Lprev();
midtri.Bond(ref tri1);
tri2.Bond(ref tri3);
// Ensure that the origin of 'farleft' is sortarray[0].
tri1.Copy(ref farleft);
// Ensure that the destination of 'farright' is sortarray[2].
tri2.Copy(ref farright);
}
else
{
// The three vertices are not collinear; the triangulation is one
// triangle, namely 'midtri'.
midtri.SetOrg(sortarray[left]);
tri1.SetDest(sortarray[left]);
tri3.SetOrg(sortarray[left]);
// Apices of tri1, tri2, and tri3 are left NULL.
if (area > 0.0)
{
// The vertices are in counterclockwise order.
midtri.SetDest(sortarray[left + 1]);
tri1.SetOrg(sortarray[left + 1]);
tri2.SetDest(sortarray[left + 1]);
midtri.SetApex(sortarray[left + 2]);
tri2.SetOrg(sortarray[left + 2]);
tri3.SetDest(sortarray[left + 2]);
}
else
{
// The vertices are in clockwise order.
midtri.SetDest(sortarray[left + 2]);
tri1.SetOrg(sortarray[left + 2]);
tri2.SetDest(sortarray[left + 2]);
midtri.SetApex(sortarray[left + 1]);
tri2.SetOrg(sortarray[left + 1]);
tri3.SetDest(sortarray[left + 1]);
}
// The topology does not depend on how the vertices are ordered.
midtri.Bond(ref tri1);
midtri.Lnext();
midtri.Bond(ref tri2);
midtri.Lnext();
midtri.Bond(ref tri3);
tri1.Lprev();
tri2.Lnext();
tri1.Bond(ref tri2);
tri1.Lprev();
tri3.Lprev();
tri1.Bond(ref tri3);
tri2.Lnext();
tri3.Lprev();
tri2.Bond(ref tri3);
// Ensure that the origin of 'farleft' is sortarray[0].
tri1.Copy(ref farleft);
// Ensure that the destination of 'farright' is sortarray[2].
if (area > 0.0)
{
tri2.Copy(ref farright);
}
else
{
farleft.Lnext(ref farright);
}
}
return;
}
else
{
// Split the vertices in half.
divider = vertices >> 1;
// Recursively triangulate each half.
DivconqRecurse(left, left + divider - 1, 1 - axis, ref farleft, ref innerleft);
//DebugWriter.Session.Write(mesh, true);
DivconqRecurse(left + divider, right, 1 - axis, ref innerright, ref farright);
//DebugWriter.Session.Write(mesh, true);
// Merge the two triangulations into one.
MergeHulls(ref farleft, ref innerleft, ref innerright, ref farright, axis);
//DebugWriter.Session.Write(mesh, true);
}
}
/// <summary>
/// Given the triangulation, and a vertex returns the minimum distance to the
/// vertices of the triangle where the given vertex located.
/// </summary>
/// <param name="newlocX"></param>
/// <param name="newlocY"></param>
/// <param name="searchtri"></param>
/// <returns></returns>
private double MinDistanceToNeighbor(double newlocX, double newlocY, ref Otri searchtri)
{
Otri horiz = default(Otri); // for search operation
LocateResult intersect = LocateResult.Outside;
Vertex v1, v2, v3, torg, tdest;
double d1, d2, d3, ahead;
//triangle ptr; // Temporary variable used by sym().
Point newvertex = new Point(newlocX, newlocY);
// printf("newvertex %f,%f\n", newvertex[0], newvertex[1]);
// Find the location of the vertex to be inserted. Check if a good
// starting triangle has already been provided by the caller.
// Find a boundary triangle.
//horiz.tri = m.dummytri;
//horiz.orient = 0;
//horiz.symself();
// Search for a triangle containing 'newvertex'.
// Start searching from the triangle provided by the caller.
// Where are we?
torg = searchtri.Org();
tdest = searchtri.Dest();
// Check the starting triangle's vertices.
if ((torg.x == newvertex.x) && (torg.y == newvertex.y))
{
intersect = LocateResult.OnVertex;
searchtri.Copy(ref horiz);
}
else if ((tdest.x == newvertex.x) && (tdest.y == newvertex.y))
{
searchtri.Lnext();
intersect = LocateResult.OnVertex;
searchtri.Copy(ref horiz);
}
else
{
// Orient 'searchtri' to fit the preconditions of calling preciselocate().
ahead = predicates.CounterClockwise(torg, tdest, newvertex);
if (ahead < 0.0)
{
// Turn around so that 'searchpoint' is to the left of the
// edge specified by 'searchtri'.
searchtri.Sym();
searchtri.Copy(ref horiz);
intersect = mesh.locator.PreciseLocate(newvertex, ref horiz, false);
}
else if (ahead == 0.0)
{
// Check if 'searchpoint' is between 'torg' and 'tdest'.
if (((torg.x < newvertex.x) == (newvertex.x < tdest.x)) &&
((torg.y < newvertex.y) == (newvertex.y < tdest.y)))
{
intersect = LocateResult.OnEdge;
searchtri.Copy(ref horiz);
}
}
else
{
searchtri.Copy(ref horiz);
intersect = mesh.locator.PreciseLocate(newvertex, ref horiz, false);
}
}
if (intersect == LocateResult.OnVertex || intersect == LocateResult.Outside)
{
// set distance to 0
//m.VertexDealloc(newvertex);
return 0.0;
}
else
{ // intersect == ONEDGE || intersect == INTRIANGLE
// find the triangle vertices
v1 = horiz.Org();
v2 = horiz.Dest();
v3 = horiz.Apex();
d1 = (v1.x - newvertex.x) * (v1.x - newvertex.x) + (v1.y - newvertex.y) * (v1.y - newvertex.y);
d2 = (v2.x - newvertex.x) * (v2.x - newvertex.x) + (v2.y - newvertex.y) * (v2.y - newvertex.y);
d3 = (v3.x - newvertex.x) * (v3.x - newvertex.x) + (v3.y - newvertex.y) * (v3.y - newvertex.y);
//m.VertexDealloc(newvertex);
// find minimum of the distance
if (d1 <= d2 && d1 <= d3)
{
return d1;
}
else if (d2 <= d3)
{
return d2;
}
else
{
return d3;
}
}
}
/// <summary>
/// Removes ghost triangles.
/// </summary>
/// <param name="startghost"></param>
/// <returns>Number of vertices on the hull.</returns>
int RemoveGhosts(ref Otri startghost)
{
Otri searchedge = default(Otri);
Otri dissolveedge = default(Otri);
Otri deadtriangle = default(Otri);
Vertex markorg;
int hullsize;
bool noPoly = !mesh.behavior.Poly;
// Find an edge on the convex hull to start point location from.
startghost.Lprev(ref searchedge);
searchedge.Sym();
mesh.dummytri.neighbors[0] = searchedge;
// Remove the bounding box and count the convex hull edges.
startghost.Copy(ref dissolveedge);
hullsize = 0;
do
{
hullsize++;
dissolveedge.Lnext(ref deadtriangle);
dissolveedge.Lprev();
dissolveedge.Sym();
// If no PSLG is involved, set the boundary markers of all the vertices
// on the convex hull. If a PSLG is used, this step is done later.
if (noPoly)
{
// Watch out for the case where all the input vertices are collinear.
if (dissolveedge.tri.id != Mesh.DUMMY)
{
markorg = dissolveedge.Org();
if (markorg.label == 0)
{
markorg.label = 1;
}
}
}
// Remove a bounding triangle from a convex hull triangle.
dissolveedge.Dissolve(mesh.dummytri);
// Find the next bounding triangle.
deadtriangle.Sym(ref dissolveedge);
// Delete the bounding triangle.
mesh.TriangleDealloc(deadtriangle.tri);
} while (!dissolveedge.Equals(startghost));
return hullsize;
}
/// <summary>
/// Find a new location for a Steiner point.
/// </summary>
/// <param name="torg"></param>
/// <param name="tdest"></param>
/// <param name="tapex"></param>
/// <param name="circumcenter"></param>
/// <param name="xi"></param>
/// <param name="eta"></param>
/// <param name="offcenter"></param>
/// <param name="badotri"></param>
private Point FindNewLocationWithoutMaxAngle(Vertex torg, Vertex tdest, Vertex tapex,
ref double xi, ref double eta, bool offcenter, Otri badotri)
{
double offconstant = behavior.offconstant;
// for calculating the distances of the edges
double xdo, ydo, xao, yao, xda, yda;
double dodist, aodist, dadist;
// for exact calculation
double denominator;
double dx, dy, dxoff, dyoff;
////////////////////////////// HALE'S VARIABLES //////////////////////////////
// keeps the difference of coordinates edge
double xShortestEdge = 0, yShortestEdge = 0, xMiddleEdge, yMiddleEdge, xLongestEdge, yLongestEdge;
// keeps the square of edge lengths
double shortestEdgeDist = 0, middleEdgeDist = 0, longestEdgeDist = 0;
// keeps the vertices according to the angle incident to that vertex in a triangle
Point smallestAngleCorner, middleAngleCorner, largestAngleCorner;
// keeps the type of orientation if the triangle
int orientation = 0;
// keeps the coordinates of circumcenter of itself and neighbor triangle circumcenter
Point myCircumcenter, neighborCircumcenter;
// keeps if bad triangle is almost good or not
int almostGood = 0;
// keeps the cosine of the largest angle
double cosMaxAngle;
bool isObtuse; // 1: obtuse 0: nonobtuse
// keeps the radius of petal
double petalRadius;
// for calculating petal center
double xPetalCtr_1, yPetalCtr_1, xPetalCtr_2, yPetalCtr_2, xPetalCtr, yPetalCtr, xMidOfShortestEdge, yMidOfShortestEdge;
double dxcenter1, dycenter1, dxcenter2, dycenter2;
// for finding neighbor
Otri neighborotri = default(Otri);
double[] thirdPoint = new double[2];
//int neighborNotFound = -1;
bool neighborNotFound;
// for keeping the vertices of the neighbor triangle
Vertex neighborvertex_1;
Vertex neighborvertex_2;
Vertex neighborvertex_3;
// dummy variables
double xi_tmp = 0, eta_tmp = 0;
//vertex thirdVertex;
// for petal intersection
double vector_x, vector_y, xMidOfLongestEdge, yMidOfLongestEdge, inter_x, inter_y;
double[] p = new double[5], voronoiOrInter = new double[4];
bool isCorrect;
// for vector calculations in perturbation
double ax, ay, d;
double pertConst = 0.06; // perturbation constant
double lengthConst = 1; // used at comparing circumcenter's distance to proposed point's distance
double justAcute = 1; // used for making the program working for one direction only
// for smoothing
int relocated = 0;// used to differentiate between calling the deletevertex and just proposing a steiner point
double[] newloc = new double[2]; // new location suggested by smoothing
double origin_x = 0, origin_y = 0; // for keeping torg safe
Otri delotri; // keeping the original orientation for relocation process
// keeps the first and second direction suggested points
double dxFirstSuggestion, dyFirstSuggestion, dxSecondSuggestion, dySecondSuggestion;
// second direction variables
double xMidOfMiddleEdge, yMidOfMiddleEdge;
////////////////////////////// END OF HALE'S VARIABLES //////////////////////////////
Statistic.CircumcenterCount++;
// Compute the circumcenter of the triangle.
xdo = tdest.x - torg.x;
ydo = tdest.y - torg.y;
xao = tapex.x - torg.x;
yao = tapex.y - torg.y;
xda = tapex.x - tdest.x;
yda = tapex.y - tdest.y;
// keeps the square of the distances
dodist = xdo * xdo + ydo * ydo;
aodist = xao * xao + yao * yao;
dadist = (tdest.x - tapex.x) * (tdest.x - tapex.x) +
(tdest.y - tapex.y) * (tdest.y - tapex.y);
// checking if the user wanted exact arithmetic or not
if (Behavior.NoExact)
{
denominator = 0.5 / (xdo * yao - xao * ydo);
}
else
{
// Use the counterclockwise() routine to ensure a positive (and
// reasonably accurate) result, avoiding any possibility of
// division by zero.
denominator = 0.5 / predicates.CounterClockwise(tdest, tapex, torg);
// Don't count the above as an orientation test.
Statistic.CounterClockwiseCount--;
}
// calculate the circumcenter in terms of distance to origin point
dx = (yao * dodist - ydo * aodist) * denominator;
dy = (xdo * aodist - xao * dodist) * denominator;
// for debugging and for keeping circumcenter to use later
// coordinate value of the circumcenter
myCircumcenter = new Point(torg.x + dx, torg.y + dy);
delotri = badotri; // save for later
///////////////// FINDING THE ORIENTATION OF TRIANGLE //////////////////
// Find the (squared) length of the triangle's shortest edge. This
// serves as a conservative estimate of the insertion radius of the
// circumcenter's parent. The estimate is used to ensure that
// the algorithm terminates even if very small angles appear in
// the input PSLG.
// find the orientation of the triangle, basically shortest and longest edges
orientation = LongestShortestEdge(aodist, dadist, dodist);
//printf("org: (%f,%f), dest: (%f,%f), apex: (%f,%f)\n",torg[0],torg[1],tdest[0],tdest[1],tapex[0],tapex[1]);
/////////////////////////////////////////////////////////////////////////////////////////////
// 123: shortest: aodist // 213: shortest: dadist // 312: shortest: dodist //
// middle: dadist // middle: aodist // middle: aodist //
// longest: dodist // longest: dodist // longest: dadist //
// 132: shortest: aodist // 231: shortest: dadist // 321: shortest: dodist //
// middle: dodist // middle: dodist // middle: dadist //
// longest: dadist // longest: aodist // longest: aodist //
/////////////////////////////////////////////////////////////////////////////////////////////
switch (orientation)
{
case 123: // assign necessary information
/// smallest angle corner: dest
/// largest angle corner: apex
xShortestEdge = xao; yShortestEdge = yao;
xMiddleEdge = xda; yMiddleEdge = yda;
xLongestEdge = xdo; yLongestEdge = ydo;
shortestEdgeDist = aodist;
middleEdgeDist = dadist;
longestEdgeDist = dodist;
smallestAngleCorner = tdest;
middleAngleCorner = torg;
largestAngleCorner = tapex;
break;
case 132: // assign necessary information
/// smallest angle corner: dest
/// largest angle corner: org
xShortestEdge = xao; yShortestEdge = yao;
xMiddleEdge = xdo; yMiddleEdge = ydo;
xLongestEdge = xda; yLongestEdge = yda;
shortestEdgeDist = aodist;
middleEdgeDist = dodist;
longestEdgeDist = dadist;
smallestAngleCorner = tdest;
middleAngleCorner = tapex;
largestAngleCorner = torg;
break;
case 213: // assign necessary information
/// smallest angle corner: org
/// largest angle corner: apex
xShortestEdge = xda; yShortestEdge = yda;
xMiddleEdge = xao; yMiddleEdge = yao;
xLongestEdge = xdo; yLongestEdge = ydo;
shortestEdgeDist = dadist;
middleEdgeDist = aodist;
longestEdgeDist = dodist;
smallestAngleCorner = torg;
middleAngleCorner = tdest;
largestAngleCorner = tapex;
break;
case 231: // assign necessary information
/// smallest angle corner: org
/// largest angle corner: dest
xShortestEdge = xda; yShortestEdge = yda;
xMiddleEdge = xdo; yMiddleEdge = ydo;
xLongestEdge = xao; yLongestEdge = yao;
shortestEdgeDist = dadist;
middleEdgeDist = dodist;
longestEdgeDist = aodist;
smallestAngleCorner = torg;
middleAngleCorner = tapex;
largestAngleCorner = tdest;
break;
case 312: // assign necessary information
/// smallest angle corner: apex
/// largest angle corner: org
xShortestEdge = xdo; yShortestEdge = ydo;
xMiddleEdge = xao; yMiddleEdge = yao;
xLongestEdge = xda; yLongestEdge = yda;
shortestEdgeDist = dodist;
middleEdgeDist = aodist;
longestEdgeDist = dadist;
smallestAngleCorner = tapex;
middleAngleCorner = tdest;
largestAngleCorner = torg;
break;
case 321: // assign necessary information
default: // TODO: is this safe?
/// smallest angle corner: apex
/// largest angle corner: dest
xShortestEdge = xdo; yShortestEdge = ydo;
xMiddleEdge = xda; yMiddleEdge = yda;
xLongestEdge = xao; yLongestEdge = yao;
shortestEdgeDist = dodist;
middleEdgeDist = dadist;
longestEdgeDist = aodist;
smallestAngleCorner = tapex;
middleAngleCorner = torg;
largestAngleCorner = tdest;
break;
}// end of switch
// check for offcenter condition
if (offcenter && (offconstant > 0.0))
{
// origin has the smallest angle
if (orientation == 213 || orientation == 231)
{
// Find the position of the off-center, as described by Alper Ungor.
dxoff = 0.5 * xShortestEdge - offconstant * yShortestEdge;
dyoff = 0.5 * yShortestEdge + offconstant * xShortestEdge;
// If the off-center is closer to destination than the
// circumcenter, use the off-center instead.
/// doubleLY BAD CASE ///
if (dxoff * dxoff + dyoff * dyoff <
(dx - xdo) * (dx - xdo) + (dy - ydo) * (dy - ydo))
{
dx = xdo + dxoff;
dy = ydo + dyoff;
}
/// ALMOST GOOD CASE ///
else
{
almostGood = 1;
}
// destination has the smallest angle
}
else if (orientation == 123 || orientation == 132)
{
// Find the position of the off-center, as described by Alper Ungor.
dxoff = 0.5 * xShortestEdge + offconstant * yShortestEdge;
dyoff = 0.5 * yShortestEdge - offconstant * xShortestEdge;
// If the off-center is closer to the origin than the
// circumcenter, use the off-center instead.
/// doubleLY BAD CASE ///
if (dxoff * dxoff + dyoff * dyoff < dx * dx + dy * dy)
{
dx = dxoff;
dy = dyoff;
}
/// ALMOST GOOD CASE ///
else
{
almostGood = 1;
}
// apex has the smallest angle
}
else
{//orientation == 312 || orientation == 321
// Find the position of the off-center, as described by Alper Ungor.
dxoff = 0.5 * xShortestEdge - offconstant * yShortestEdge;
dyoff = 0.5 * yShortestEdge + offconstant * xShortestEdge;
// If the off-center is closer to the origin than the
// circumcenter, use the off-center instead.
/// doubleLY BAD CASE ///
if (dxoff * dxoff + dyoff * dyoff < dx * dx + dy * dy)
{
dx = dxoff;
dy = dyoff;
}
/// ALMOST GOOD CASE ///
else
{
almostGood = 1;
}
}
}
// if the bad triangle is almost good, apply our approach
if (almostGood == 1)
{
/// calculate cosine of largest angle ///
cosMaxAngle = (middleEdgeDist + shortestEdgeDist - longestEdgeDist) / (2 * Math.Sqrt(middleEdgeDist) * Math.Sqrt(shortestEdgeDist));
if (cosMaxAngle < 0.0)
{
// obtuse
isObtuse = true;
}
else if (Math.Abs(cosMaxAngle - 0.0) <= EPS)
{
// right triangle (largest angle is 90 degrees)
isObtuse = true;
}
else
{
// nonobtuse
isObtuse = false;
}
/// RELOCATION (LOCAL SMOOTHING) ///
/// check for possible relocation of one of triangle's points ///
relocated = DoSmoothing(delotri, torg, tdest, tapex, ref newloc);
/// if relocation is possible, delete that vertex and insert a vertex at the new location ///
if (relocated > 0)
{
Statistic.RelocationCount++;
dx = newloc[0] - torg.x;
dy = newloc[1] - torg.y;
origin_x = torg.x; // keep for later use
origin_y = torg.y;
switch (relocated)
{
case 1:
//printf("Relocate: (%f,%f)\n", torg[0],torg[1]);
mesh.DeleteVertex(ref delotri);
break;
case 2:
//printf("Relocate: (%f,%f)\n", tdest[0],tdest[1]);
delotri.Lnext();
mesh.DeleteVertex(ref delotri);
break;
case 3:
//printf("Relocate: (%f,%f)\n", tapex[0],tapex[1]);
delotri.Lprev();
mesh.DeleteVertex(ref delotri);
break;
}
}
else
{
// calculate radius of the petal according to angle constraint
// first find the visible region, PETAL
// find the center of the circle and radius
petalRadius = Math.Sqrt(shortestEdgeDist) / (2 * Math.Sin(behavior.MinAngle * Math.PI / 180.0));
/// compute two possible centers of the petal ///
// finding the center
// first find the middle point of smallest edge
xMidOfShortestEdge = (middleAngleCorner.x + largestAngleCorner.x) / 2.0;
yMidOfShortestEdge = (middleAngleCorner.y + largestAngleCorner.y) / 2.0;
// two possible centers
xPetalCtr_1 = xMidOfShortestEdge + Math.Sqrt(petalRadius * petalRadius - (shortestEdgeDist / 4)) * (middleAngleCorner.y -
largestAngleCorner.y) / Math.Sqrt(shortestEdgeDist);
yPetalCtr_1 = yMidOfShortestEdge + Math.Sqrt(petalRadius * petalRadius - (shortestEdgeDist / 4)) * (largestAngleCorner.x -
middleAngleCorner.x) / Math.Sqrt(shortestEdgeDist);
xPetalCtr_2 = xMidOfShortestEdge - Math.Sqrt(petalRadius * petalRadius - (shortestEdgeDist / 4)) * (middleAngleCorner.y -
largestAngleCorner.y) / Math.Sqrt(shortestEdgeDist);
yPetalCtr_2 = yMidOfShortestEdge - Math.Sqrt(petalRadius * petalRadius - (shortestEdgeDist / 4)) * (largestAngleCorner.x -
middleAngleCorner.x) / Math.Sqrt(shortestEdgeDist);
// find the correct circle since there will be two possible circles
// calculate the distance to smallest angle corner
dxcenter1 = (xPetalCtr_1 - smallestAngleCorner.x) * (xPetalCtr_1 - smallestAngleCorner.x);
dycenter1 = (yPetalCtr_1 - smallestAngleCorner.y) * (yPetalCtr_1 - smallestAngleCorner.y);
dxcenter2 = (xPetalCtr_2 - smallestAngleCorner.x) * (xPetalCtr_2 - smallestAngleCorner.x);
dycenter2 = (yPetalCtr_2 - smallestAngleCorner.y) * (yPetalCtr_2 - smallestAngleCorner.y);
// whichever is closer to smallest angle corner, it must be the center
if (dxcenter1 + dycenter1 <= dxcenter2 + dycenter2)
{
xPetalCtr = xPetalCtr_1; yPetalCtr = yPetalCtr_1;
}
else
{
xPetalCtr = xPetalCtr_2; yPetalCtr = yPetalCtr_2;
}
/// find the third point of the neighbor triangle ///
neighborNotFound = GetNeighborsVertex(badotri, middleAngleCorner.x, middleAngleCorner.y,
smallestAngleCorner.x, smallestAngleCorner.y, ref thirdPoint, ref neighborotri);
/// find the circumcenter of the neighbor triangle ///
dxFirstSuggestion = dx; // if we cannot find any appropriate suggestion, we use circumcenter
dyFirstSuggestion = dy;
// if there is a neighbor triangle
if (!neighborNotFound)
{
neighborvertex_1 = neighborotri.Org();
neighborvertex_2 = neighborotri.Dest();
neighborvertex_3 = neighborotri.Apex();
// now calculate neighbor's circumcenter which is the voronoi site
neighborCircumcenter = predicates.FindCircumcenter(neighborvertex_1, neighborvertex_2, neighborvertex_3,
ref xi_tmp, ref eta_tmp);
/// compute petal and Voronoi edge intersection ///
// in order to avoid degenerate cases, we need to do a vector based calculation for line
vector_x = (middleAngleCorner.y - smallestAngleCorner.y);//(-y, x)
vector_y = smallestAngleCorner.x - middleAngleCorner.x;
vector_x = myCircumcenter.x + vector_x;
vector_y = myCircumcenter.y + vector_y;
// by intersecting bisectors you will end up with the one you want to walk on
// then this line and circle should be intersected
CircleLineIntersection(myCircumcenter.x, myCircumcenter.y, vector_x, vector_y,
xPetalCtr, yPetalCtr, petalRadius, ref p);
/// choose the correct intersection point ///
// calculate middle point of the longest edge(bisector)
xMidOfLongestEdge = (middleAngleCorner.x + smallestAngleCorner.x) / 2.0;
yMidOfLongestEdge = (middleAngleCorner.y + smallestAngleCorner.y) / 2.0;
// we need to find correct intersection point, since line intersects circle twice
isCorrect = ChooseCorrectPoint(xMidOfLongestEdge, yMidOfLongestEdge, p[3], p[4],
myCircumcenter.x, myCircumcenter.y, isObtuse);
// make sure which point is the correct one to be considered
if (isCorrect)
{
inter_x = p[3];
inter_y = p[4];
}
else
{
inter_x = p[1];
inter_y = p[2];
}
/// check if there is a Voronoi vertex between before intersection ///
// check if the voronoi vertex is between the intersection and circumcenter
PointBetweenPoints(inter_x, inter_y, myCircumcenter.x, myCircumcenter.y,
neighborCircumcenter.x, neighborCircumcenter.y, ref voronoiOrInter);
/// determine the point to be suggested ///
if (p[0] > 0.0)
{ // there is at least one intersection point
// if it is between circumcenter and intersection
// if it returns 1.0 this means we have a voronoi vertex within feasible region
if (Math.Abs(voronoiOrInter[0] - 1.0) <= EPS)
{
if (IsBadTriangleAngle(middleAngleCorner.x, middleAngleCorner.y, largestAngleCorner.x, largestAngleCorner.y, neighborCircumcenter.x, neighborCircumcenter.y))
{
// go back to circumcenter
dxFirstSuggestion = dx;
dyFirstSuggestion = dy;
}
else
{ // we are not creating a bad triangle
// neighbor's circumcenter is suggested
dxFirstSuggestion = voronoiOrInter[2] - torg.x;
dyFirstSuggestion = voronoiOrInter[3] - torg.y;
}
}
else
{ // there is no voronoi vertex between intersection point and circumcenter
if (IsBadTriangleAngle(largestAngleCorner.x, largestAngleCorner.y, middleAngleCorner.x, middleAngleCorner.y, inter_x, inter_y))
{
// if it is inside feasible region, then insert v2
// apply perturbation
// find the distance between circumcenter and intersection point
d = Math.Sqrt((inter_x - myCircumcenter.x) * (inter_x - myCircumcenter.x) +
(inter_y - myCircumcenter.y) * (inter_y - myCircumcenter.y));
// then find the vector going from intersection point to circumcenter
ax = myCircumcenter.x - inter_x;
ay = myCircumcenter.y - inter_y;
ax = ax / d;
ay = ay / d;
// now calculate the new intersection point which is perturbated towards the circumcenter
inter_x = inter_x + ax * pertConst * Math.Sqrt(shortestEdgeDist);
inter_y = inter_y + ay * pertConst * Math.Sqrt(shortestEdgeDist);
if (IsBadTriangleAngle(middleAngleCorner.x, middleAngleCorner.y, largestAngleCorner.x, largestAngleCorner.y, inter_x, inter_y))
{
// go back to circumcenter
dxFirstSuggestion = dx;
dyFirstSuggestion = dy;
}
else
{
// intersection point is suggested
dxFirstSuggestion = inter_x - torg.x;
dyFirstSuggestion = inter_y - torg.y;
}
}
else
{
// intersection point is suggested
dxFirstSuggestion = inter_x - torg.x;
dyFirstSuggestion = inter_y - torg.y;
}
}
/// if it is an acute triangle, check if it is a good enough location ///
// for acute triangle case, we need to check if it is ok to use either of them
if ((smallestAngleCorner.x - myCircumcenter.x) * (smallestAngleCorner.x - myCircumcenter.x) +
(smallestAngleCorner.y - myCircumcenter.y) * (smallestAngleCorner.y - myCircumcenter.y) >
lengthConst * ((smallestAngleCorner.x - (dxFirstSuggestion + torg.x)) *
(smallestAngleCorner.x - (dxFirstSuggestion + torg.x)) +
(smallestAngleCorner.y - (dyFirstSuggestion + torg.y)) *
(smallestAngleCorner.y - (dyFirstSuggestion + torg.y))))
{
// use circumcenter
dxFirstSuggestion = dx;
dyFirstSuggestion = dy;
}// else we stick to what we have found
}// intersection point
}// if it is on the boundary, meaning no neighbor triangle in this direction, try other direction
/// DO THE SAME THING FOR THE OTHER DIRECTION ///
/// find the third point of the neighbor triangle ///
neighborNotFound = GetNeighborsVertex(badotri, largestAngleCorner.x, largestAngleCorner.y,
smallestAngleCorner.x, smallestAngleCorner.y, ref thirdPoint, ref neighborotri);
/// find the circumcenter of the neighbor triangle ///
dxSecondSuggestion = dx; // if we cannot find any appropriate suggestion, we use circumcenter
dySecondSuggestion = dy;
// if there is a neighbor triangle
if (!neighborNotFound)
{
neighborvertex_1 = neighborotri.Org();
neighborvertex_2 = neighborotri.Dest();
neighborvertex_3 = neighborotri.Apex();
// now calculate neighbor's circumcenter which is the voronoi site
neighborCircumcenter = predicates.FindCircumcenter(neighborvertex_1, neighborvertex_2, neighborvertex_3,
ref xi_tmp, ref eta_tmp);
/// compute petal and Voronoi edge intersection ///
// in order to avoid degenerate cases, we need to do a vector based calculation for line
vector_x = (largestAngleCorner.y - smallestAngleCorner.y);//(-y, x)
vector_y = smallestAngleCorner.x - largestAngleCorner.x;
vector_x = myCircumcenter.x + vector_x;
vector_y = myCircumcenter.y + vector_y;
// by intersecting bisectors you will end up with the one you want to walk on
// then this line and circle should be intersected
CircleLineIntersection(myCircumcenter.x, myCircumcenter.y, vector_x, vector_y,
xPetalCtr, yPetalCtr, petalRadius, ref p);
/// choose the correct intersection point ///
// calcuwedgeslate middle point of the longest edge(bisector)
xMidOfMiddleEdge = (largestAngleCorner.x + smallestAngleCorner.x) / 2.0;
yMidOfMiddleEdge = (largestAngleCorner.y + smallestAngleCorner.y) / 2.0;
// we need to find correct intersection point, since line intersects circle twice
// this direction is always ACUTE
isCorrect = ChooseCorrectPoint(xMidOfMiddleEdge, yMidOfMiddleEdge, p[3], p[4],
myCircumcenter.x, myCircumcenter.y, false/*(isObtuse+1)%2*/);
// make sure which point is the correct one to be considered
if (isCorrect)
{
inter_x = p[3];
inter_y = p[4];
}
else
{
inter_x = p[1];
inter_y = p[2];
}
/// check if there is a Voronoi vertex between before intersection ///
// check if the voronoi vertex is between the intersection and circumcenter
PointBetweenPoints(inter_x, inter_y, myCircumcenter.x, myCircumcenter.y,
neighborCircumcenter.x, neighborCircumcenter.y, ref voronoiOrInter);
/// determine the point to be suggested ///
if (p[0] > 0.0)
{ // there is at least one intersection point
// if it is between circumcenter and intersection
// if it returns 1.0 this means we have a voronoi vertex within feasible region
if (Math.Abs(voronoiOrInter[0] - 1.0) <= EPS)
{
if (IsBadTriangleAngle(middleAngleCorner.x, middleAngleCorner.y, largestAngleCorner.x, largestAngleCorner.y, neighborCircumcenter.x, neighborCircumcenter.y))
{
// go back to circumcenter
dxSecondSuggestion = dx;
dySecondSuggestion = dy;
}
else
{ // we are not creating a bad triangle
// neighbor's circumcenter is suggested
dxSecondSuggestion = voronoiOrInter[2] - torg.x;
dySecondSuggestion = voronoiOrInter[3] - torg.y;
}
}
else
{ // there is no voronoi vertex between intersection point and circumcenter
if (IsBadTriangleAngle(middleAngleCorner.x, middleAngleCorner.y, largestAngleCorner.x, largestAngleCorner.y, inter_x, inter_y))
{
// if it is inside feasible region, then insert v2
// apply perturbation
// find the distance between circumcenter and intersection point
d = Math.Sqrt((inter_x - myCircumcenter.x) * (inter_x - myCircumcenter.x) +
(inter_y - myCircumcenter.y) * (inter_y - myCircumcenter.y));
// then find the vector going from intersection point to circumcenter
ax = myCircumcenter.x - inter_x;
ay = myCircumcenter.y - inter_y;
ax = ax / d;
ay = ay / d;
// now calculate the new intersection point which is perturbated towards the circumcenter
inter_x = inter_x + ax * pertConst * Math.Sqrt(shortestEdgeDist);
inter_y = inter_y + ay * pertConst * Math.Sqrt(shortestEdgeDist);
if (IsBadTriangleAngle(middleAngleCorner.x, middleAngleCorner.y, largestAngleCorner.x, largestAngleCorner.y, inter_x, inter_y))
{
// go back to circumcenter
dxSecondSuggestion = dx;
dySecondSuggestion = dy;
}
else
{
// intersection point is suggested
dxSecondSuggestion = inter_x - torg.x;
dySecondSuggestion = inter_y - torg.y;
}
}
else
{
// intersection point is suggested
dxSecondSuggestion = inter_x - torg.x;
dySecondSuggestion = inter_y - torg.y;
}
}
/// if it is an acute triangle, check if it is a good enough location ///
// for acute triangle case, we need to check if it is ok to use either of them
if ((smallestAngleCorner.x - myCircumcenter.x) * (smallestAngleCorner.x - myCircumcenter.x) +
(smallestAngleCorner.y - myCircumcenter.y) * (smallestAngleCorner.y - myCircumcenter.y) >
lengthConst * ((smallestAngleCorner.x - (dxSecondSuggestion + torg.x)) *
(smallestAngleCorner.x - (dxSecondSuggestion + torg.x)) +
(smallestAngleCorner.y - (dySecondSuggestion + torg.y)) *
(smallestAngleCorner.y - (dySecondSuggestion + torg.y))))
{
// use circumcenter
dxSecondSuggestion = dx;
dySecondSuggestion = dy;
}// else we stick on what we have found
}
}// if it is on the boundary, meaning no neighbor triangle in this direction, the other direction might be ok
if (isObtuse)
{
//obtuse: do nothing
dx = dxFirstSuggestion;
dy = dyFirstSuggestion;
}
else
{ // acute : consider other direction
if (justAcute * ((smallestAngleCorner.x - (dxSecondSuggestion + torg.x)) *
(smallestAngleCorner.x - (dxSecondSuggestion + torg.x)) +
(smallestAngleCorner.y - (dySecondSuggestion + torg.y)) *
(smallestAngleCorner.y - (dySecondSuggestion + torg.y))) >
(smallestAngleCorner.x - (dxFirstSuggestion + torg.x)) *
(smallestAngleCorner.x - (dxFirstSuggestion + torg.x)) +
(smallestAngleCorner.y - (dyFirstSuggestion + torg.y)) *
(smallestAngleCorner.y - (dyFirstSuggestion + torg.y)))
{
dx = dxSecondSuggestion;
dy = dySecondSuggestion;
}
else
{
dx = dxFirstSuggestion;
dy = dyFirstSuggestion;
}
}// end if obtuse
}// end of relocation
}// end of almostGood
Point circumcenter = new Point();
if (relocated <= 0)
{
circumcenter.x = torg.x + dx;
circumcenter.y = torg.y + dy;
}
else
{
circumcenter.x = origin_x + dx;
circumcenter.y = origin_y + dy;
}
xi = (yao * dx - xao * dy) * (2.0 * denominator);
eta = (xdo * dy - ydo * dx) * (2.0 * denominator);
return circumcenter;
}
/// <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.label == 0)
{
triorg.label = subsegmark;
}
if (tridest.label == 0)
{
tridest.label = subsegmark;
}
// Check if there's already a subsegment here.
tri.Pivot(ref newsubseg);
if (newsubseg.seg.hash == DUMMY)
{
// 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.Sym();
oppotri.SegBond(ref newsubseg);
newsubseg.seg.boundary = subsegmark;
}
else if (newsubseg.seg.boundary == 0)
{
newsubseg.seg.boundary = subsegmark;
}
}
/// <summary>
/// Test a triangle for quality and size.
/// </summary>
/// <param name="testtri">Triangle to check.</param>
/// <remarks>
/// Tests a triangle to see if it satisfies the minimum angle condition and
/// the maximum area condition. Triangles that aren't up to spec are added
/// to the bad triangle queue.
/// </remarks>
public void TestTriangle(ref Otri testtri)
{
Otri tri1 = default(Otri), tri2 = default(Otri);
Osub testsub = default(Osub);
Vertex torg, tdest, tapex;
Vertex base1, base2;
Vertex org1, dest1, org2, dest2;
Vertex joinvertex;
double dxod, dyod, dxda, dyda, dxao, dyao;
double dxod2, dyod2, dxda2, dyda2, dxao2, dyao2;
double apexlen, orglen, destlen, minedge;
double angle;
double area;
double dist1, dist2;
double maxangle;
torg = testtri.Org();
tdest = testtri.Dest();
tapex = testtri.Apex();
dxod = torg.x - tdest.x;
dyod = torg.y - tdest.y;
dxda = tdest.x - tapex.x;
dyda = tdest.y - tapex.y;
dxao = tapex.x - torg.x;
dyao = tapex.y - torg.y;
dxod2 = dxod * dxod;
dyod2 = dyod * dyod;
dxda2 = dxda * dxda;
dyda2 = dyda * dyda;
dxao2 = dxao * dxao;
dyao2 = dyao * dyao;
// Find the lengths of the triangle's three edges.
apexlen = dxod2 + dyod2;
orglen = dxda2 + dyda2;
destlen = dxao2 + dyao2;
if ((apexlen < orglen) && (apexlen < destlen))
{
// The edge opposite the apex is shortest.
minedge = apexlen;
// Find the square of the cosine of the angle at the apex.
angle = dxda * dxao + dyda * dyao;
angle = angle * angle / (orglen * destlen);
base1 = torg;
base2 = tdest;
testtri.Copy(ref tri1);
}
else if (orglen < destlen)
{
// The edge opposite the origin is shortest.
minedge = orglen;
// Find the square of the cosine of the angle at the origin.
angle = dxod * dxao + dyod * dyao;
angle = angle * angle / (apexlen * destlen);
base1 = tdest;
base2 = tapex;
testtri.Lnext(ref tri1);
}
else
{
// The edge opposite the destination is shortest.
minedge = destlen;
// Find the square of the cosine of the angle at the destination.
angle = dxod * dxda + dyod * dyda;
angle = angle * angle / (apexlen * orglen);
base1 = tapex;
base2 = torg;
testtri.Lprev(ref tri1);
}
if (behavior.VarArea || behavior.fixedArea || (behavior.UserTest != null))
{
// Check whether the area is larger than permitted.
area = 0.5 * (dxod * dyda - dyod * dxda);
if (behavior.fixedArea && (area > behavior.MaxArea))
{
// Add this triangle to the list of bad triangles.
queue.Enqueue(ref testtri, minedge, tapex, torg, tdest);
return;
}
// Nonpositive area constraints are treated as unconstrained.
if ((behavior.VarArea) && (area > testtri.tri.area) && (testtri.tri.area > 0.0))
{
// Add this triangle to the list of bad triangles.
queue.Enqueue(ref testtri, minedge, tapex, torg, tdest);
return;
}
// Check whether the user thinks this triangle is too large.
if ((behavior.UserTest != null) && behavior.UserTest(testtri.tri, area))
{
queue.Enqueue(ref testtri, minedge, tapex, torg, tdest);
return;
}
}
// find the maximum edge and accordingly the pqr orientation
if ((apexlen > orglen) && (apexlen > destlen))
{
// The edge opposite the apex is longest.
// maxedge = apexlen;
// Find the cosine of the angle at the apex.
maxangle = (orglen + destlen - apexlen) / (2 * Math.Sqrt(orglen * destlen));
}
else if (orglen > destlen)
{
// The edge opposite the origin is longest.
// maxedge = orglen;
// Find the cosine of the angle at the origin.
maxangle = (apexlen + destlen - orglen) / (2 * Math.Sqrt(apexlen * destlen));
}
else
{
// The edge opposite the destination is longest.
// maxedge = destlen;
// Find the cosine of the angle at the destination.
maxangle = (apexlen + orglen - destlen) / (2 * Math.Sqrt(apexlen * orglen));
}
// Check whether the angle is smaller than permitted.
if ((angle > behavior.goodAngle) || (maxangle < behavior.maxGoodAngle && behavior.MaxAngle != 0.0))
{
// Use the rules of Miller, Pav, and Walkington to decide that certain
// triangles should not be split, even if they have bad angles.
// A skinny triangle is not split if its shortest edge subtends a
// small input angle, and both endpoints of the edge lie on a
// concentric circular shell. For convenience, I make a small
// adjustment to that rule: I check if the endpoints of the edge
// both lie in segment interiors, equidistant from the apex where
// the two segments meet.
// First, check if both points lie in segment interiors.
if ((base1.type == VertexType.SegmentVertex) &&
(base2.type == VertexType.SegmentVertex))
{
// Check if both points lie in a common segment. If they do, the
// skinny triangle is enqueued to be split as usual.
tri1.Pivot(ref testsub);
if (testsub.seg.hash == Mesh.DUMMY)
{
// No common segment. Find a subsegment that contains 'torg'.
tri1.Copy(ref tri2);
do
{
tri1.Oprev();
tri1.Pivot(ref testsub);
} while (testsub.seg.hash == Mesh.DUMMY);
// Find the endpoints of the containing segment.
org1 = testsub.SegOrg();
dest1 = testsub.SegDest();
// Find a subsegment that contains 'tdest'.
do
{
tri2.Dnext();
tri2.Pivot(ref testsub);
} while (testsub.seg.hash == Mesh.DUMMY);
// Find the endpoints of the containing segment.
org2 = testsub.SegOrg();
dest2 = testsub.SegDest();
// Check if the two containing segments have an endpoint in common.
joinvertex = null;
if ((dest1.x == org2.x) && (dest1.y == org2.y))
{
joinvertex = dest1;
}
else if ((org1.x == dest2.x) && (org1.y == dest2.y))
{
joinvertex = org1;
}
if (joinvertex != null)
{
// Compute the distance from the common endpoint (of the two
// segments) to each of the endpoints of the shortest edge.
dist1 = ((base1.x - joinvertex.x) * (base1.x - joinvertex.x) +
(base1.y - joinvertex.y) * (base1.y - joinvertex.y));
dist2 = ((base2.x - joinvertex.x) * (base2.x - joinvertex.x) +
(base2.y - joinvertex.y) * (base2.y - joinvertex.y));
// If the two distances are equal, don't split the triangle.
if ((dist1 < 1.001 * dist2) && (dist1 > 0.999 * dist2))
{
// Return now to avoid enqueueing the bad triangle.
return;
}
}
}
}
// Add this triangle to the list of bad triangles.
queue.Enqueue(ref testtri, minedge, tapex, torg, tdest);
}
}
/// <summary>
/// Transform two triangles to two different triangles by flipping an edge
/// counterclockwise within a quadrilateral.
/// </summary>
/// <param name="flipedge">Handle to the edge that will be flipped.</param>
/// <remarks>Imagine the original triangles, abc and bad, oriented so that the
/// shared edge ab lies in a horizontal plane, with the vertex b on the left
/// and the vertex a on the right. The vertex c lies below the edge, and
/// the vertex d lies above the edge. The 'flipedge' handle holds the edge
/// ab of triangle abc, and is directed left, from vertex a to vertex b.
///
/// The triangles abc and bad are deleted and replaced by the triangles cdb
/// and dca. The triangles that represent abc and bad are NOT deallocated;
/// they are reused for dca and cdb, respectively. Hence, any handles that
/// may have held the original triangles are still valid, although not
/// directed as they were before.
///
/// Upon completion of this routine, the 'flipedge' handle holds the edge
/// dc of triangle dca, and is directed down, from vertex d to vertex c.
/// (Hence, the two triangles have rotated counterclockwise.)
///
/// WARNING: This transformation is geometrically valid only if the
/// quadrilateral adbc is convex. Furthermore, this transformation is
/// valid only if there is not a subsegment between the triangles abc and
/// bad. This routine does not check either of these preconditions, and
/// it is the responsibility of the calling routine to ensure that they are
/// met. If they are not, the streets shall be filled with wailing and
/// gnashing of teeth.
///
/// Terminology
///
/// A "local transformation" replaces a small set of triangles with another
/// set of triangles. This may or may not involve inserting or deleting a
/// vertex.
///
/// The term "casing" is used to describe the set of triangles that are
/// attached to the triangles being transformed, but are not transformed
/// themselves. Think of the casing as a fixed hollow structure inside
/// which all the action happens. A "casing" is only defined relative to
/// a single transformation; each occurrence of a transformation will
/// involve a different casing.
/// </remarks>
internal void Flip(ref Otri flipedge)
{
Otri botleft = default(Otri), botright = default(Otri);
Otri topleft = default(Otri), topright = default(Otri);
Otri top = default(Otri);
Otri botlcasing = default(Otri), botrcasing = default(Otri);
Otri toplcasing = default(Otri), toprcasing = default(Otri);
Osub botlsubseg = default(Osub), botrsubseg = default(Osub);
Osub toplsubseg = default(Osub), toprsubseg = default(Osub);
Vertex leftvertex, rightvertex, botvertex;
Vertex farvertex;
// Identify the vertices of the quadrilateral.
rightvertex = flipedge.Org();
leftvertex = flipedge.Dest();
botvertex = flipedge.Apex();
flipedge.Sym(ref top);
// SELF CHECK
//if (top.triangle.id == DUMMY)
//{
// logger.Error("Attempt to flip on boundary.", "Mesh.Flip()");
// flipedge.LnextSelf();
// return;
//}
//if (checksegments)
//{
// flipedge.SegPivot(ref toplsubseg);
// if (toplsubseg.ss != Segment.Empty)
// {
// logger.Error("Attempt to flip a segment.", "Mesh.Flip()");
// flipedge.LnextSelf();
// return;
// }
//}
farvertex = top.Apex();
// Identify the casing of the quadrilateral.
top.Lprev(ref topleft);
topleft.Sym(ref toplcasing);
top.Lnext(ref topright);
topright.Sym(ref toprcasing);
flipedge.Lnext(ref botleft);
botleft.Sym(ref botlcasing);
flipedge.Lprev(ref botright);
botright.Sym(ref botrcasing);
// Rotate the quadrilateral one-quarter turn counterclockwise.
topleft.Bond(ref botlcasing);
botleft.Bond(ref botrcasing);
botright.Bond(ref toprcasing);
topright.Bond(ref toplcasing);
if (checksegments)
{
// Check for subsegments and rebond them to the quadrilateral.
topleft.Pivot(ref toplsubseg);
botleft.Pivot(ref botlsubseg);
botright.Pivot(ref botrsubseg);
topright.Pivot(ref toprsubseg);
if (toplsubseg.seg.hash == DUMMY)
{
topright.SegDissolve(dummysub);
}
else
{
topright.SegBond(ref toplsubseg);
}
if (botlsubseg.seg.hash == DUMMY)
{
topleft.SegDissolve(dummysub);
}
else
{
topleft.SegBond(ref botlsubseg);
}
if (botrsubseg.seg.hash == DUMMY)
{
botleft.SegDissolve(dummysub);
}
else
{
botleft.SegBond(ref botrsubseg);
}
if (toprsubseg.seg.hash == DUMMY)
{
botright.SegDissolve(dummysub);
}
else
{
botright.SegBond(ref toprsubseg);
}
}
// New vertex assignments for the rotated quadrilateral.
flipedge.SetOrg(farvertex);
flipedge.SetDest(botvertex);
flipedge.SetApex(rightvertex);
top.SetOrg(botvertex);
top.SetDest(farvertex);
top.SetApex(leftvertex);
}
