Merge pull request #6 from saurabhb17/master

minor additions

1 files changed, 284 insertions, 0 deletions

diff --git a/polygon/poly2tri/sweep/sweep.h b/polygon/poly2tri/sweep/sweep.h
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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.
+ */
+/**
+ * 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