MaximumInscribedCircle.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (c) 2020 Martin Davis
 * Copyright (C) 2020 Paul Ramsey <pramsey@cleverelephant.ca>
 *
 * 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: algorithm/construct/MaximumInscribedCircle.java
 * https://github.com/locationtech/jts/commit/f0b9a808bdf8a973de435f737e37b7a221e231cb
 *
 **********************************************************************/
 
#pragma once
 
#include <geos/geom/Coordinate.h>
#include <geos/geom/Point.h>
#include <geos/geom/Envelope.h>
#include <geos/algorithm/locate/IndexedPointInAreaLocator.h>
#include <geos/operation/distance/IndexedFacetDistance.h>
 
#include <memory>
#include <queue>
 
 
 
namespace geos {
namespace geom {
class Coordinate;
class Envelope;
class Geometry;
class GeometryFactory;
class LineString;
class Point;
}
}
 
namespace geos {
namespace algorithm { // geos::algorithm
namespace construct { // geos::algorithm::construct
 
class GEOS_DLL MaximumInscribedCircle {
 
    using IndexedPointInAreaLocator = geos::algorithm::locate::IndexedPointInAreaLocator;
    using IndexedFacetDistance = geos::operation::distance::IndexedFacetDistance;
 
public:
 
    MaximumInscribedCircle(const geom::Geometry* polygonal, double tolerance);
    ~MaximumInscribedCircle() = default;
 
    std::unique_ptr<geom::Point> getCenter();
 
    std::unique_ptr<geom::Point> getRadiusPoint();
 
    std::unique_ptr<geom::LineString> getRadiusLine();
 
    bool isRadiusWithin(double maxRadius);
 
    static std::unique_ptr<geom::Point> getCenter(const geom::Geometry* polygonal, double tolerance);
 
    static std::unique_ptr<geom::LineString> getRadiusLine(const geom::Geometry* polygonal, double tolerance);
 
    static bool isRadiusWithin(const geom::Geometry* polygonal, double maxRadius);
 
    static std::size_t computeMaximumIterations(const geom::Geometry* geom, double toleranceDist);
 
private:
 
    /* private members */
    const geom::Geometry* inputGeom;
    std::unique_ptr<geom::Geometry> inputGeomBoundary;
    double tolerance;
    IndexedFacetDistance indexedDistance;
    IndexedPointInAreaLocator ptLocator;
    const geom::GeometryFactory* factory;
    bool done;
    geom::CoordinateXY centerPt;
    geom::CoordinateXY radiusPt;
    double maximumRadius = -1;
 
    /* private constant */
    static constexpr double MAX_RADIUS_FRACTION = 0.0001;
 
    /* private methods */
    double distanceToBoundary(const geom::Point& pt);
    double distanceToBoundary(double x, double y);
    void compute();
    void computeApproximation();
    void createResult(const geom::CoordinateXY& c, const geom::CoordinateXY& r);
 
    /* private class */
    class Cell {
    private:
        static constexpr double SQRT2 = 1.4142135623730951;
        double x;
        double y;
        double hSize;
        double distance;
        double maxDist;
 
    public:
        Cell(double p_x, double p_y, double p_hSize, double p_distanceToBoundary)
            : x(p_x)
            , y(p_y)
            , hSize(p_hSize)
            , distance(p_distanceToBoundary)
            , maxDist(p_distanceToBoundary+(p_hSize*SQRT2))
        {};
 
        geom::Envelope getEnvelope() const
        {
            geom::Envelope env(x-hSize, x+hSize, y-hSize, y+hSize);
            return env;
        }
 
        double getMaxDistance() const
        {
            return maxDist;
        }
        double getDistance() const
        {
            return distance;
        }
        double getHSize() const
        {
            return hSize;
        }
        double getX() const
        {
            return x;
        }
        double getY() const
        {
            return y;
        }
 
        bool operator< (const Cell& rhs) const
        {
            return maxDist <  rhs.maxDist;
        }
 
        bool operator> (const Cell& rhs) const
        {
            return maxDist >  rhs.maxDist;
        }
 
        bool operator==(const Cell& rhs) const
        {
            return maxDist == rhs.maxDist;
        }
 
        using CellQueue = std::priority_queue<Cell>;
    };
 
    void createInitialGrid(const geom::Envelope* env, Cell::CellQueue& cellQueue);
    Cell createInteriorPointCell(const geom::Geometry* geom);
 
};
 
 
} // geos::algorithm::construct
} // geos::algorithm
} // geos