279 lines
8.1 KiB
C++
279 lines
8.1 KiB
C++
/*
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* Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
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* http://code.google.com/p/poly2tri/
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of Poly2Tri nor the names of its contributors may be
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* used to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* Sweep-line, Constrained Delauney Triangulation (CDT) See: Domiter, V. and
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* Zalik, B.(2008)'Sweep-line algorithm for constrained Delaunay triangulation',
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* International Journal of Geographical Information Science
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*
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* "FlipScan" Constrained Edge Algorithm invented by Thomas Åhlén, thahlen@gmail.com
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*/
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#ifndef SWEEP_H
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#define SWEEP_H
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#include <vector>
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namespace p2t {
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class SweepContext;
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struct Node;
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struct Point;
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struct Edge;
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class Triangle;
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class Sweep
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{
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public:
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/**
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* Triangulate
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*
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* @param tcx
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*/
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void Triangulate(SweepContext& tcx);
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/**
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* Destructor - clean up memory
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*/
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~Sweep();
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private:
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/**
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* Start sweeping the Y-sorted point set from bottom to top
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*
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* @param tcx
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*/
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void SweepPoints(SweepContext& tcx);
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/**
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* Find closes node to the left of the new point and
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* create a new triangle. If needed new holes and basins
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* will be filled to.
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*
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* @param tcx
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* @param point
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* @return
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*/
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Node& PointEvent(SweepContext& tcx, Point& point);
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/**
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*
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*
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* @param tcx
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* @param edge
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* @param node
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*/
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void EdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
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void EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point);
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/**
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* Creates a new front triangle and legalize it
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*
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* @param tcx
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* @param point
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* @param node
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* @return
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*/
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Node& NewFrontTriangle(SweepContext& tcx, Point& point, Node& node);
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/**
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* Adds a triangle to the advancing front to fill a hole.
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* @param tcx
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* @param node - middle node, that is the bottom of the hole
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*/
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void Fill(SweepContext& tcx, Node& node);
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/**
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* Returns true if triangle was legalized
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*/
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bool Legalize(SweepContext& tcx, Triangle& t);
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/**
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* <b>Requirement</b>:<br>
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* 1. a,b and c form a triangle.<br>
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* 2. a and d is know to be on opposite side of bc<br>
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* <pre>
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* a
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* +
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* / \
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* / \
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* b/ \c
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* +-------+
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* / d \
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* / \
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* </pre>
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* <b>Fact</b>: d has to be in area B to have a chance to be inside the circle formed by
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* a,b and c<br>
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* d is outside B if orient2d(a,b,d) or orient2d(c,a,d) is CW<br>
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* This preknowledge gives us a way to optimize the incircle test
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* @param a - triangle point, opposite d
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* @param b - triangle point
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* @param c - triangle point
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* @param d - point opposite a
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* @return true if d is inside circle, false if on circle edge
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*/
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bool Incircle(Point& pa, Point& pb, Point& pc, Point& pd);
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/**
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* Rotates a triangle pair one vertex CW
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*<pre>
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* n2 n2
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* P +-----+ P +-----+
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* | t /| |\ t |
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* | / | | \ |
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* n1| / |n3 n1| \ |n3
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* | / | after CW | \ |
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* |/ oT | | oT \|
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* +-----+ oP +-----+
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* n4 n4
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* </pre>
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*/
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void RotateTrianglePair(Triangle& t, Point& p, Triangle& ot, Point& op);
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/**
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* Fills holes in the Advancing Front
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*
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*
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* @param tcx
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* @param n
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*/
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void FillAdvancingFront(SweepContext& tcx, Node& n);
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/**
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*
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* @param node - middle node
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* @return the angle between 3 front nodes
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*/
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double HoleAngle(Node& node);
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/**
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* The basin angle is decided against the horizontal line [1,0]
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*/
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double BasinAngle(Node& node);
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/**
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* Fills a basin that has formed on the Advancing Front to the right
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* of given node.<br>
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* First we decide a left,bottom and right node that forms the
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* boundaries of the basin. Then we do a reqursive fill.
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*
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* @param tcx
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* @param node - starting node, this or next node will be left node
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*/
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void FillBasin(SweepContext& tcx, Node& node);
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/**
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* Recursive algorithm to fill a Basin with triangles
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*
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* @param tcx
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* @param node - bottom_node
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* @param cnt - counter used to alternate on even and odd numbers
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*/
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void FillBasinReq(SweepContext& tcx, Node* node);
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bool IsShallow(SweepContext& tcx, Node& node);
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bool IsEdgeSideOfTriangle(Triangle& triangle, Point& ep, Point& eq);
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void FillEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
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void FillRightAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
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void FillRightBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FillLeftAboveEdgeEvent(SweepContext& tcx, Edge* edge, Node* node);
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void FillLeftBelowEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FillLeftConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node);
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void FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p);
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/**
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* After a flip we have two triangles and know that only one will still be
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* intersecting the edge. So decide which to contiune with and legalize the other
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*
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* @param tcx
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* @param o - should be the result of an orient2d( eq, op, ep )
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* @param t - triangle 1
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* @param ot - triangle 2
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* @param p - a point shared by both triangles
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* @param op - another point shared by both triangles
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* @return returns the triangle still intersecting the edge
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*/
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Triangle& NextFlipTriangle(SweepContext& tcx, int o, Triangle& t, Triangle& ot, Point& p, Point& op);
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/**
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* When we need to traverse from one triangle to the next we need
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* the point in current triangle that is the opposite point to the next
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* triangle.
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*
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* @param ep
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* @param eq
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* @param ot
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* @param op
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* @return
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*/
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Point& NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op);
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/**
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* Scan part of the FlipScan algorithm<br>
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* When a triangle pair isn't flippable we will scan for the next
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* point that is inside the flip triangle scan area. When found
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* we generate a new flipEdgeEvent
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*
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* @param tcx
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* @param ep - last point on the edge we are traversing
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* @param eq - first point on the edge we are traversing
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* @param flipTriangle - the current triangle sharing the point eq with edge
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* @param t
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* @param p
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*/
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void FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle, Triangle& t, Point& p);
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void FinalizationPolygon(SweepContext& tcx);
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std::vector<Node*> nodes_;
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};
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}
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#endif
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