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Diffstat (limited to 'polygon/poly2tri/sweep/sweep.h')
| -rw-r--r-- | polygon/poly2tri/sweep/sweep.h | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/polygon/poly2tri/sweep/sweep.h b/polygon/poly2tri/sweep/sweep.h new file mode 100644 index 0000000..07822d1 --- /dev/null +++ b/polygon/poly2tri/sweep/sweep.h @@ -0,0 +1,284 @@ +/* + * 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. + */ +/** + * Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V. and + * Zalik, B.(2008)'Sweep-line algorithm for constrained Delaunay triangulation', + * International Journal of Geographical Information Science + * + * "FlipScan" Constrained Edge Algorithm invented by Thomas Åhlén, thahlen@gmail.com + */ + +#ifndef SWEEP_H +#define SWEEP_H + +#include <vector> + +namespace p2t { + +class SweepContext; +struct Node; +struct Point; +struct Edge; +class Triangle; + +class Sweep +{ +public: + + /** + * Triangulate + * + * @param tcx + */ + void Triangulate(SweepContext& tcx); + + /** + * Destructor - clean up memory + */ + ~Sweep(); + +private: + + /** + * Start sweeping the Y-sorted point set from bottom to top + * + * @param tcx + */ + void SweepPoints(SweepContext& tcx); + + /** + * Find closes node to the left of the new point and + * create a new triangle. If needed new holes and basins + * will be filled to. + * + * @param tcx + * @param point + * @return + */ + Node& PointEvent(SweepContext& tcx, Point& point); + + /** + * + * + * @param tcx + * @param edge + * @param node + */ + void EdgeEvent(SweepContext& tcx, Edge* edge, Node* node); + + void EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point); + + /** + * Creates a new front triangle and legalize it + * + * @param tcx + * @param point + * @param node + * @return + */ + Node& NewFrontTriangle(SweepContext& tcx, Point& point, Node& node); + + /** + * Adds a triangle to the advancing front to fill a hole. + * @param tcx + * @param node - middle node, that is the bottom of the hole + */ + void Fill(SweepContext& tcx, Node& node); + + /** + * Returns true if triangle was legalized + */ + bool Legalize(SweepContext& tcx, Triangle& t); + + /** + * <b>Requirement</b>:<br> + * 1. a,b and c form a triangle.<br> + * 2. a and d is know to be on opposite side of bc<br> + * <pre> + * a + * + + * / \ + * / \ + * b/ \c + * +-------+ + * / d \ + * / \ + * </pre> + * <b>Fact</b>: d has to be in area B to have a chance to be inside the circle formed by + * a,b and c<br> + * d is outside B if orient2d(a,b,d) or orient2d(c,a,d) is CW<br> + * This preknowledge gives us a way to optimize the incircle test + * @param pa - triangle point, opposite d + * @param pb - triangle point + * @param pc - triangle point + * @param pd - point opposite a + * @return true if d is inside circle, false if on circle edge + */ + bool Incircle(Point& pa, Point& pb, Point& pc, Point& pd); + + /** + * Rotates a triangle pair one vertex CW + *<pre> + * n2 n2 + * P +-----+ P +-----+ + * | t /| |\ t | + * | / | | \ | + * n1| / |n3 n1| \ |n3 + * | / | after CW | \ | + * |/ oT | | oT \| + * +-----+ oP +-----+ + * n4 n4 + * </pre> + */ + void RotateTrianglePair(Triangle& t, Point& p, Triangle& ot, Point& op); + + /** + * Fills holes in the Advancing Front + * + * + * @param tcx + * @param n + */ + void FillAdvancingFront(SweepContext& tcx, Node& n); + + // Decision-making about when to Fill hole. + // Contributed by ToolmakerSteve2 + bool LargeHole_DontFill(Node* node); + bool AngleExceeds90Degrees(Point* origin, Point* pa, Point* pb); + bool AngleExceedsPlus90DegreesOrIsNegative(Point* origin, Point* pa, Point* pb); + double Angle(Point& origin, Point& pa, Point& pb); + + /** + * + * @param node - middle node + * @return the angle between 3 front nodes + */ + double HoleAngle(Node& node); + + /** + * The basin angle is decided against the horizontal line [1,0] + */ + double BasinAngle(Node& node); + + /** + * Fills a basin that has formed on the Advancing Front to the right + * of given node.<br> + * First we decide a left,bottom and right node that forms the + * boundaries of the basin. Then we do a reqursive fill. + * + * @param tcx + * @param node - starting node, this or next node will be left node + */ + void FillBasin(SweepContext& tcx, Node& node); + + /** + * Recursive algorithm to fill a Basin with triangles + * + * @param tcx + * @param node - bottom_node + */ + void FillBasinReq(SweepContext& tcx, Node* node); + + bool IsShallow(SweepContext& tcx, Node& node); + + bool IsEdgeSideOfTriangle(Triangle& triangle, Point& ep, Point& eq); + + void FillEdgeEvent(SweepContext& tcx, Edge* edge, Node* node); + + void FillRightAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node); + + void FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FillLeftAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node); + + void FillLeftBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node); + + void FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p); + + /** + * After a flip we have two triangles and know that only one will still be + * intersecting the edge. So decide which to contiune with and legalize the other + * + * @param tcx + * @param o - should be the result of an orient2d( eq, op, ep ) + * @param t - triangle 1 + * @param ot - triangle 2 + * @param p - a point shared by both triangles + * @param op - another point shared by both triangles + * @return returns the triangle still intersecting the edge + */ + Triangle& NextFlipTriangle(SweepContext& tcx, int o, Triangle& t, Triangle& ot, Point& p, Point& op); + + /** + * When we need to traverse from one triangle to the next we need + * the point in current triangle that is the opposite point to the next + * triangle. + * + * @param ep + * @param eq + * @param ot + * @param op + * @return + */ + Point& NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op); + + /** + * Scan part of the FlipScan algorithm<br> + * When a triangle pair isn't flippable we will scan for the next + * point that is inside the flip triangle scan area. When found + * we generate a new flipEdgeEvent + * + * @param tcx + * @param ep - last point on the edge we are traversing + * @param eq - first point on the edge we are traversing + * @param flipTriangle - the current triangle sharing the point eq with edge + * @param t + * @param p + */ + void FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle, Triangle& t, Point& p); + + void FinalizationPolygon(SweepContext& tcx); + + std::vector<Node*> nodes_; + +}; + +} + +#endif |