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/*
* Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
* http://code.google.com/p/poly2tri/
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither the name of Poly2Tri nor the names of its contributors may be
* used to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "sweep.h"
#include "sweep_context.h"
#include "advancing_front.h"
#include "../common/utils.h"
#include <cassert>
#include <stdexcept>
namespace p2t {
// Triangulate simple polygon with holes
void Sweep::Triangulate(SweepContext& tcx)
{
tcx.InitTriangulation();
tcx.CreateAdvancingFront();
// Sweep points; build mesh
SweepPoints(tcx);
// Clean up
FinalizationPolygon(tcx);
}
void Sweep::SweepPoints(SweepContext& tcx)
{
for (size_t i = 1; i < tcx.point_count(); i++) {
Point& point = *tcx.GetPoint(i);
Node* node = &PointEvent(tcx, point);
for (unsigned int i = 0; i < point.edge_list.size(); i++) {
EdgeEvent(tcx, point.edge_list[i], node);
}
}
}
void Sweep::FinalizationPolygon(SweepContext& tcx)
{
// Get an Internal triangle to start with
Triangle* t = tcx.front()->head()->next->triangle;
Point* p = tcx.front()->head()->next->point;
while (!t->GetConstrainedEdgeCW(*p)) {
t = t->NeighborCCW(*p);
}
// Collect interior triangles constrained by edges
tcx.MeshClean(*t);
}
Node& Sweep::PointEvent(SweepContext& tcx, Point& point)
{
Node& node = tcx.LocateNode(point);
Node& new_node = NewFrontTriangle(tcx, point, node);
// Only need to check +epsilon since point never have smaller
// x value than node due to how we fetch nodes from the front
if (point.x <= node.point->x + EPSILON) {
Fill(tcx, node);
}
//tcx.AddNode(new_node);
FillAdvancingFront(tcx, new_node);
return new_node;
}
void Sweep::EdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
{
tcx.edge_event.constrained_edge = edge;
tcx.edge_event.right = (edge->p->x > edge->q->x);
if (IsEdgeSideOfTriangle(*node->triangle, *edge->p, *edge->q)) {
return;
}
// For now we will do all needed filling
// TODO: integrate with flip process might give some better performance
// but for now this avoid the issue with cases that needs both flips and fills
FillEdgeEvent(tcx, edge, node);
EdgeEvent(tcx, *edge->p, *edge->q, node->triangle, *edge->q);
}
void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point)
{
if (IsEdgeSideOfTriangle(*triangle, ep, eq)) {
return;
}
Point* p1 = triangle->PointCCW(point);
Orientation o1 = Orient2d(eq, *p1, ep);
if (o1 == COLLINEAR) {
if( triangle->Contains(&eq, p1)) {
triangle->MarkConstrainedEdge(&eq, p1 );
// We are modifying the constraint maybe it would be better to
// not change the given constraint and just keep a variable for the new constraint
tcx.edge_event.constrained_edge->q = p1;
triangle = &triangle->NeighborAcross(point);
EdgeEvent( tcx, ep, *p1, triangle, *p1 );
} else {
std::runtime_error("EdgeEvent - collinear points not supported");
assert(0);
}
return;
}
Point* p2 = triangle->PointCW(point);
Orientation o2 = Orient2d(eq, *p2, ep);
if (o2 == COLLINEAR) {
if( triangle->Contains(&eq, p2)) {
triangle->MarkConstrainedEdge(&eq, p2 );
// We are modifying the constraint maybe it would be better to
// not change the given constraint and just keep a variable for the new constraint
tcx.edge_event.constrained_edge->q = p2;
triangle = &triangle->NeighborAcross(point);
EdgeEvent( tcx, ep, *p2, triangle, *p2 );
} else {
std::runtime_error("EdgeEvent - collinear points not supported");
assert(0);
}
return;
}
if (o1 == o2) {
// Need to decide if we are rotating CW or CCW to get to a triangle
// that will cross edge
if (o1 == CW) {
triangle = triangle->NeighborCCW(point);
} else{
triangle = triangle->NeighborCW(point);
}
EdgeEvent(tcx, ep, eq, triangle, point);
} else {
// This triangle crosses constraint so lets flippin start!
FlipEdgeEvent(tcx, ep, eq, triangle, point);
}
}
bool Sweep::IsEdgeSideOfTriangle(Triangle& triangle, Point& ep, Point& eq)
{
const int index = triangle.EdgeIndex(&ep, &eq);
if (index != -1) {
triangle.MarkConstrainedEdge(index);
Triangle* t = triangle.GetNeighbor(index);
if (t) {
t->MarkConstrainedEdge(&ep, &eq);
}
return true;
}
return false;
}
Node& Sweep::NewFrontTriangle(SweepContext& tcx, Point& point, Node& node)
{
Triangle* triangle = new Triangle(point, *node.point, *node.next->point);
triangle->MarkNeighbor(*node.triangle);
tcx.AddToMap(triangle);
Node* new_node = new Node(point);
nodes_.push_back(new_node);
new_node->next = node.next;
new_node->prev = &node;
node.next->prev = new_node;
node.next = new_node;
if (!Legalize(tcx, *triangle)) {
tcx.MapTriangleToNodes(*triangle);
}
return *new_node;
}
void Sweep::Fill(SweepContext& tcx, Node& node)
{
Triangle* triangle = new Triangle(*node.prev->point, *node.point, *node.next->point);
// TODO: should copy the constrained_edge value from neighbor triangles
// for now constrained_edge values are copied during the legalize
triangle->MarkNeighbor(*node.prev->triangle);
triangle->MarkNeighbor(*node.triangle);
tcx.AddToMap(triangle);
// Update the advancing front
node.prev->next = node.next;
node.next->prev = node.prev;
// If it was legalized the triangle has already been mapped
if (!Legalize(tcx, *triangle)) {
tcx.MapTriangleToNodes(*triangle);
}
}
void Sweep::FillAdvancingFront(SweepContext& tcx, Node& n)
{
// Fill right holes
Node* node = n.next;
while (node->next) {
// if HoleAngle exceeds 90 degrees then break.
if (LargeHole_DontFill(node)) break;
Fill(tcx, *node);
node = node->next;
}
// Fill left holes
node = n.prev;
while (node->prev) {
// if HoleAngle exceeds 90 degrees then break.
if (LargeHole_DontFill(node)) break;
Fill(tcx, *node);
node = node->prev;
}
// Fill right basins
if (n.next && n.next->next) {
const double angle = BasinAngle(n);
if (angle < PI_3div4) {
FillBasin(tcx, n);
}
}
}
// True if HoleAngle exceeds 90 degrees.
bool Sweep::LargeHole_DontFill(const Node* node) const {
const Node* nextNode = node->next;
const Node* prevNode = node->prev;
if (!AngleExceeds90Degrees(node->point, nextNode->point, prevNode->point))
return false;
// Check additional points on front.
const Node* next2Node = nextNode->next;
// "..Plus.." because only want angles on same side as point being added.
if ((next2Node != NULL) && !AngleExceedsPlus90DegreesOrIsNegative(node->point, next2Node->point, prevNode->point))
return false;
const Node* prev2Node = prevNode->prev;
// "..Plus.." because only want angles on same side as point being added.
if ((prev2Node != NULL) && !AngleExceedsPlus90DegreesOrIsNegative(node->point, nextNode->point, prev2Node->point))
return false;
return true;
}
bool Sweep::AngleExceeds90Degrees(const Point* origin, const Point* pa, const Point* pb) const {
const double angle = Angle(origin, pa, pb);
return ((angle > PI_div2) || (angle < -PI_div2));
}
bool Sweep::AngleExceedsPlus90DegreesOrIsNegative(const Point* origin, const Point* pa, const Point* pb) const {
const double angle = Angle(origin, pa, pb);
return (angle > PI_div2) || (angle < 0);
}
double Sweep::Angle(const Point* origin, const Point* pa, const Point* pb) const {
/* Complex plane
* ab = cosA +i*sinA
* ab = (ax + ay*i)(bx + by*i) = (ax*bx + ay*by) + i(ax*by-ay*bx)
* atan2(y,x) computes the principal value of the argument function
* applied to the complex number x+iy
* Where x = ax*bx + ay*by
* y = ax*by - ay*bx
*/
const double px = origin->x;
const double py = origin->y;
const double ax = pa->x- px;
const double ay = pa->y - py;
const double bx = pb->x - px;
const double by = pb->y - py;
const double x = ax * by - ay * bx;
const double y = ax * bx + ay * by;
return atan2(x, y);
}
double Sweep::BasinAngle(const Node& node) const
{
const double ax = node.point->x - node.next->next->point->x;
const double ay = node.point->y - node.next->next->point->y;
return atan2(ay, ax);
}
double Sweep::HoleAngle(const Node& node) const
{
/* Complex plane
* ab = cosA +i*sinA
* ab = (ax + ay*i)(bx + by*i) = (ax*bx + ay*by) + i(ax*by-ay*bx)
* atan2(y,x) computes the principal value of the argument function
* applied to the complex number x+iy
* Where x = ax*bx + ay*by
* y = ax*by - ay*bx
*/
const double ax = node.next->point->x - node.point->x;
const double ay = node.next->point->y - node.point->y;
const double bx = node.prev->point->x - node.point->x;
const double by = node.prev->point->y - node.point->y;
return atan2(ax * by - ay * bx, ax * bx + ay * by);
}
bool Sweep::Legalize(SweepContext& tcx, Triangle& t)
{
// To legalize a triangle we start by finding if any of the three edges
// violate the Delaunay condition
for (int i = 0; i < 3; i++) {
if (t.delaunay_edge[i])
continue;
Triangle* ot = t.GetNeighbor(i);
if (ot) {
Point* p = t.GetPoint(i);
Point* op = ot->OppositePoint(t, *p);
int oi = ot->Index(op);
// If this is a Constrained Edge or a Delaunay Edge(only during recursive legalization)
// then we should not try to legalize
if (ot->constrained_edge[oi] || ot->delaunay_edge[oi]) {
t.constrained_edge[i] = ot->constrained_edge[oi];
continue;
}
bool inside = Incircle(*p, *t.PointCCW(*p), *t.PointCW(*p), *op);
if (inside) {
// Lets mark this shared edge as Delaunay
t.delaunay_edge[i] = true;
ot->delaunay_edge[oi] = true;
// Lets rotate shared edge one vertex CW to legalize it
RotateTrianglePair(t, *p, *ot, *op);
// We now got one valid Delaunay Edge shared by two triangles
// This gives us 4 new edges to check for Delaunay
// Make sure that triangle to node mapping is done only one time for a specific triangle
bool not_legalized = !Legalize(tcx, t);
if (not_legalized) {
tcx.MapTriangleToNodes(t);
}
not_legalized = !Legalize(tcx, *ot);
if (not_legalized)
tcx.MapTriangleToNodes(*ot);
// Reset the Delaunay edges, since they only are valid Delaunay edges
// until we add a new triangle or point.
// XXX: need to think about this. Can these edges be tried after we
// return to previous recursive level?
t.delaunay_edge[i] = false;
ot->delaunay_edge[oi] = false;
// If triangle have been legalized no need to check the other edges since
// the recursive legalization will handles those so we can end here.
return true;
}
}
}
return false;
}
bool Sweep::Incircle(const Point& pa, const Point& pb, const Point& pc, const Point& pd) const
{
const double adx = pa.x - pd.x;
const double ady = pa.y - pd.y;
const double bdx = pb.x - pd.x;
const double bdy = pb.y - pd.y;
const double adxbdy = adx * bdy;
const double bdxady = bdx * ady;
const double oabd = adxbdy - bdxady;
if (oabd <= 0)
return false;
const double cdx = pc.x - pd.x;
const double cdy = pc.y - pd.y;
const double cdxady = cdx * ady;
const double adxcdy = adx * cdy;
const double ocad = cdxady - adxcdy;
if (ocad <= 0)
return false;
const double bdxcdy = bdx * cdy;
const double cdxbdy = cdx * bdy;
const double alift = adx * adx + ady * ady;
const double blift = bdx * bdx + bdy * bdy;
const double clift = cdx * cdx + cdy * cdy;
const double det = alift * (bdxcdy - cdxbdy) + blift * ocad + clift * oabd;
return det > 0;
}
void Sweep::RotateTrianglePair(Triangle& t, Point& p, Triangle& ot, Point& op) const
{
Triangle* n1, *n2, *n3, *n4;
n1 = t.NeighborCCW(p);
n2 = t.NeighborCW(p);
n3 = ot.NeighborCCW(op);
n4 = ot.NeighborCW(op);
bool ce1, ce2, ce3, ce4;
ce1 = t.GetConstrainedEdgeCCW(p);
ce2 = t.GetConstrainedEdgeCW(p);
ce3 = ot.GetConstrainedEdgeCCW(op);
ce4 = ot.GetConstrainedEdgeCW(op);
bool de1, de2, de3, de4;
de1 = t.GetDelunayEdgeCCW(p);
de2 = t.GetDelunayEdgeCW(p);
de3 = ot.GetDelunayEdgeCCW(op);
de4 = ot.GetDelunayEdgeCW(op);
t.Legalize(p, op);
ot.Legalize(op, p);
// Remap delaunay_edge
ot.SetDelunayEdgeCCW(p, de1);
t.SetDelunayEdgeCW(p, de2);
t.SetDelunayEdgeCCW(op, de3);
ot.SetDelunayEdgeCW(op, de4);
// Remap constrained_edge
ot.SetConstrainedEdgeCCW(p, ce1);
t.SetConstrainedEdgeCW(p, ce2);
t.SetConstrainedEdgeCCW(op, ce3);
ot.SetConstrainedEdgeCW(op, ce4);
// Remap neighbors
// XXX: might optimize the markNeighbor by keeping track of
// what side should be assigned to what neighbor after the
// rotation. Now mark neighbor does lots of testing to find
// the right side.
t.ClearNeighbors();
ot.ClearNeighbors();
if (n1) ot.MarkNeighbor(*n1);
if (n2) t.MarkNeighbor(*n2);
if (n3) t.MarkNeighbor(*n3);
if (n4) ot.MarkNeighbor(*n4);
t.MarkNeighbor(ot);
}
void Sweep::FillBasin(SweepContext& tcx, Node& node)
{
if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
tcx.basin.left_node = node.next->next;
} else {
tcx.basin.left_node = node.next;
}
// Find the bottom and right node
tcx.basin.bottom_node = tcx.basin.left_node;
while (tcx.basin.bottom_node->next
&& tcx.basin.bottom_node->point->y >= tcx.basin.bottom_node->next->point->y) {
tcx.basin.bottom_node = tcx.basin.bottom_node->next;
}
if (tcx.basin.bottom_node == tcx.basin.left_node) {
// No valid basin
return;
}
tcx.basin.right_node = tcx.basin.bottom_node;
while (tcx.basin.right_node->next
&& tcx.basin.right_node->point->y < tcx.basin.right_node->next->point->y) {
tcx.basin.right_node = tcx.basin.right_node->next;
}
if (tcx.basin.right_node == tcx.basin.bottom_node) {
// No valid basins
return;
}
tcx.basin.width = tcx.basin.right_node->point->x - tcx.basin.left_node->point->x;
tcx.basin.left_highest = tcx.basin.left_node->point->y > tcx.basin.right_node->point->y;
FillBasinReq(tcx, tcx.basin.bottom_node);
}
void Sweep::FillBasinReq(SweepContext& tcx, Node* node)
{
// if shallow stop filling
if (IsShallow(tcx, *node)) {
return;
}
Fill(tcx, *node);
if (node->prev == tcx.basin.left_node && node->next == tcx.basin.right_node) {
return;
} else if (node->prev == tcx.basin.left_node) {
Orientation o = Orient2d(*node->point, *node->next->point, *node->next->next->point);
if (o == CW) {
return;
}
node = node->next;
} else if (node->next == tcx.basin.right_node) {
Orientation o = Orient2d(*node->point, *node->prev->point, *node->prev->prev->point);
if (o == CCW) {
return;
}
node = node->prev;
} else {
// Continue with the neighbor node with lowest Y value
if (node->prev->point->y < node->next->point->y) {
node = node->prev;
} else {
node = node->next;
}
}
FillBasinReq(tcx, node);
}
bool Sweep::IsShallow(SweepContext& tcx, Node& node)
{
double height;
if (tcx.basin.left_highest) {
height = tcx.basin.left_node->point->y - node.point->y;
} else {
height = tcx.basin.right_node->point->y - node.point->y;
}
// if shallow stop filling
if (tcx.basin.width > height) {
return true;
}
return false;
}
void Sweep::FillEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
{
if (tcx.edge_event.right) {
FillRightAboveEdgeEvent(tcx, edge, node);
} else {
FillLeftAboveEdgeEvent(tcx, edge, node);
}
}
void Sweep::FillRightAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
{
while (node->next->point->x < edge->p->x) {
// Check if next node is below the edge
if (Orient2d(*edge->q, *node->next->point, *edge->p) == CCW) {
FillRightBelowEdgeEvent(tcx, edge, *node);
} else {
node = node->next;
}
}
}
void Sweep::FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
if (node.point->x < edge->p->x) {
if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
// Concave
FillRightConcaveEdgeEvent(tcx, edge, node);
} else{
// Convex
FillRightConvexEdgeEvent(tcx, edge, node);
// Retry this one
FillRightBelowEdgeEvent(tcx, edge, node);
}
}
}
void Sweep::FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
Fill(tcx, *node.next);
if (node.next->point != edge->p) {
// Next above or below edge?
if (Orient2d(*edge->q, *node.next->point, *edge->p) == CCW) {
// Below
if (Orient2d(*node.point, *node.next->point, *node.next->next->point) == CCW) {
// Next is concave
FillRightConcaveEdgeEvent(tcx, edge, node);
} else {
// Next is convex
}
}
}
}
void Sweep::FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
// Next concave or convex?
if (Orient2d(*node.next->point, *node.next->next->point, *node.next->next->next->point) == CCW) {
// Concave
FillRightConcaveEdgeEvent(tcx, edge, *node.next);
} else{
// Convex
// Next above or below edge?
if (Orient2d(*edge->q, *node.next->next->point, *edge->p) == CCW) {
// Below
FillRightConvexEdgeEvent(tcx, edge, *node.next);
} else{
// Above
}
}
}
void Sweep::FillLeftAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
{
while (node->prev->point->x > edge->p->x) {
// Check if next node is below the edge
if (Orient2d(*edge->q, *node->prev->point, *edge->p) == CW) {
FillLeftBelowEdgeEvent(tcx, edge, *node);
} else {
node = node->prev;
}
}
}
void Sweep::FillLeftBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
if (node.point->x > edge->p->x) {
if (Orient2d(*node.point, *node.prev->point, *node.prev->prev->point) == CW) {
// Concave
FillLeftConcaveEdgeEvent(tcx, edge, node);
} else {
// Convex
FillLeftConvexEdgeEvent(tcx, edge, node);
// Retry this one
FillLeftBelowEdgeEvent(tcx, edge, node);
}
}
}
void Sweep::FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
// Next concave or convex?
if (Orient2d(*node.prev->point, *node.prev->prev->point, *node.prev->prev->prev->point) == CW) {
// Concave
FillLeftConcaveEdgeEvent(tcx, edge, *node.prev);
} else{
// Convex
// Next above or below edge?
if (Orient2d(*edge->q, *node.prev->prev->point, *edge->p) == CW) {
// Below
FillLeftConvexEdgeEvent(tcx, edge, *node.prev);
} else{
// Above
}
}
}
void Sweep::FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
{
Fill(tcx, *node.prev);
if (node.prev->point != edge->p) {
// Next above or below edge?
if (Orient2d(*edge->q, *node.prev->point, *edge->p) == CW) {
// Below
if (Orient2d(*node.point, *node.prev->point, *node.prev->prev->point) == CW) {
// Next is concave
FillLeftConcaveEdgeEvent(tcx, edge, node);
} else{
// Next is convex
}
}
}
}
void Sweep::FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p)
{
Triangle& ot = t->NeighborAcross(p);
Point& op = *ot.OppositePoint(*t, p);
if (InScanArea(p, *t->PointCCW(p), *t->PointCW(p), op)) {
// Lets rotate shared edge one vertex CW
RotateTrianglePair(*t, p, ot, op);
tcx.MapTriangleToNodes(*t);
tcx.MapTriangleToNodes(ot);
if (p == eq && op == ep) {
if (eq == *tcx.edge_event.constrained_edge->q && ep == *tcx.edge_event.constrained_edge->p) {
t->MarkConstrainedEdge(&ep, &eq);
ot.MarkConstrainedEdge(&ep, &eq);
Legalize(tcx, *t);
Legalize(tcx, ot);
} else {
// XXX: I think one of the triangles should be legalized here?
}
} else {
Orientation o = Orient2d(eq, op, ep);
t = &NextFlipTriangle(tcx, (int)o, *t, ot, p, op);
FlipEdgeEvent(tcx, ep, eq, t, p);
}
} else {
Point& newP = NextFlipPoint(ep, eq, ot, op);
FlipScanEdgeEvent(tcx, ep, eq, *t, ot, newP);
EdgeEvent(tcx, ep, eq, t, p);
}
}
Triangle& Sweep::NextFlipTriangle(SweepContext& tcx, int o, Triangle& t, Triangle& ot, Point& p, Point& op)
{
if (o == CCW) {
// ot is not crossing edge after flip
int edge_index = ot.EdgeIndex(&p, &op);
ot.delaunay_edge[edge_index] = true;
Legalize(tcx, ot);
ot.ClearDelunayEdges();
return t;
}
// t is not crossing edge after flip
int edge_index = t.EdgeIndex(&p, &op);
t.delaunay_edge[edge_index] = true;
Legalize(tcx, t);
t.ClearDelunayEdges();
return ot;
}
Point& Sweep::NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op)
{
Orientation o2d = Orient2d(eq, op, ep);
if (o2d == CW) {
// Right
return *ot.PointCCW(op);
} else if (o2d == CCW) {
// Left
return *ot.PointCW(op);
}
throw std::runtime_error("[Unsupported] Opposing point on constrained edge");
}
void Sweep::FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle,
Triangle& t, Point& p)
{
Triangle& ot = t.NeighborAcross(p);
Point& op = *ot.OppositePoint(t, p);
if (InScanArea(eq, *flip_triangle.PointCCW(eq), *flip_triangle.PointCW(eq), op)) {
// flip with new edge op->eq
FlipEdgeEvent(tcx, eq, op, &ot, op);
// TODO: Actually I just figured out that it should be possible to
// improve this by getting the next ot and op before the the above
// flip and continue the flipScanEdgeEvent here
// set new ot and op here and loop back to inScanArea test
// also need to set a new flip_triangle first
// Turns out at first glance that this is somewhat complicated
// so it will have to wait.
} else{
Point& newP = NextFlipPoint(ep, eq, ot, op);
FlipScanEdgeEvent(tcx, ep, eq, flip_triangle, ot, newP);
}
}
Sweep::~Sweep() {
// Clean up memory
for(size_t i = 0; i < nodes_.size(); i++) {
delete nodes_[i];
}
}
}