/// <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>
/// 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>
/// 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>
/// 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);
}
/// <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);
}
/// <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>
/// 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();
}
}
}
