DYT/Tool/OpenSceneGraph-3.6.5/include/geos/geomgraph/EdgeEnd.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2011 Sandro Santilli <strk@kbt.io>
 * Copyright (C) 2005-2006 Refractions Research Inc.
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation.
 * See the COPYING file for more information.
 *
 **********************************************************************
 *
 * Last port: geomgraph/EdgeEnd.java r428 (JTS-1.12+)
 *
 **********************************************************************/


#pragma once

#include <geos/export.h>
#include <geos/geom/Coordinate.h>  // for p0,p1
#include <geos/geomgraph/Label.h>  // for composition

#include <string>

// Forward declarations
namespace geos {
namespace algorithm {
class BoundaryNodeRule;
}
namespace geomgraph {
class Edge;
class Node;
}
}

namespace geos {
namespace geomgraph { // geos.geomgraph

/** \brief
 * Models the end of an edge incident on a node.
 *
 * EdgeEnds have a direction
 * determined by the direction of the ray from the initial
 * point to the next point.
 * EdgeEnds are comparable under the ordering
 * "a has a greater angle with the x-axis than b".
 * This ordering is used to sort EdgeEnds around a node.
 */
class GEOS_DLL EdgeEnd /* non-final */ {

public:

    friend std::ostream& operator<< (std::ostream&, const EdgeEnd&);

    EdgeEnd();

    virtual
    ~EdgeEnd() {}

    /**
     * NOTES:
     *  - Copies the given Label
     *  - keeps a pointer to given Edge, make sure it's
     *    not deleted before the EdgeEnd.
     *  - copies given Coordinates (maybe we should avoid that)
     */
    EdgeEnd(Edge* newEdge, const geom::Coordinate& newP0,
            const geom::Coordinate& newP1,
            const Label& newLabel);

    /**
     * NOTES:
     *  - keeps a pointer to given Edge, make sure it's
     *    not deleted before the EdgeEnd.
     *  - copies given Coordinates (maybe we should avoid that)
     */
    EdgeEnd(Edge* newEdge, const geom::Coordinate& newP0,
            const geom::Coordinate& newP1);

    Edge*
    getEdge()
    {
        return edge;
    }
    //virtual Edge* getEdge() { return edge; }

    Label&
    getLabel()
    {
        return label;
    }

    const Label&
    getLabel() const
    {
        return label;
    }

    geom::Coordinate& getCoordinate() {
        return p0;
    }

    const geom::Coordinate&
    getCoordinate() const
    {
        return p0;
    }

    geom::Coordinate& getDirectedCoordinate();

    int getQuadrant();

    double getDx();

    double getDy();

    void setNode(Node* newNode);

    Node* getNode();

    int compareTo(const EdgeEnd* e) const;

    /**
     * Implements the total order relation:
     *
     *    a has a greater angle with the positive x-axis than b
     *
     * Using the obvious algorithm of simply computing the angle
     * is not robust, since the angle calculation is obviously
     * susceptible to roundoff.
     * A robust algorithm is:
     * - first compare the quadrant.  If the quadrants
     *   are different, it it trivial to determine which vector
     *   is "greater".
     * - if the vectors lie in the same quadrant, the
     *   computeOrientation function can be used to decide
     *   the relative orientation of the vectors.
     */
    int compareDirection(const EdgeEnd* e) const;

    virtual void computeLabel(const algorithm::BoundaryNodeRule& bnr);

    virtual std::string print() const;

protected:

    Edge* edge;// the parent edge of this edge end

    Label label;

    EdgeEnd(Edge* newEdge);

    void init(const geom::Coordinate& newP0,
                      const geom::Coordinate& newP1);

private:

    /// the node this edge end originates at
    Node* node;

    /// points of initial line segment. FIXME: do we need a copy here ?
    geom::Coordinate p0, p1;

    /// the direction vector for this edge from its starting point
    double dx, dy;

    int quadrant;
};

std::ostream& operator<< (std::ostream&, const EdgeEnd&);

struct GEOS_DLL  EdgeEndLT {
    bool
    operator()(const EdgeEnd* s1, const EdgeEnd* s2) const
    {
        return s1->compareTo(s2) < 0;
    }
};

} // namespace geos.geomgraph
} // namespace geos