Circle.h

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/*
 * This file is part of sphgeom.
 *
 * Developed for the LSST Data Management System.
 * This product includes software developed by the LSST Project
 * (http://www.lsst.org).
 * See the COPYRIGHT file at the top-level directory of this distribution
 * for details of code ownership.
 *
 * This software is dual licensed under the GNU General Public License and also
 * under a 3-clause BSD license. Recipients may choose which of these licenses
 * to use; please see the files gpl-3.0.txt and/or bsd_license.txt,
 * respectively.  If you choose the GPL option then the following text applies
 * (but note that there is still no warranty even if you opt for BSD instead):
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef LSST_SPHGEOM_CIRCLE_H_
#define LSST_SPHGEOM_CIRCLE_H_
 
 
#include <iosfwd>
#include <cstdint>
 
#include "Region.h"
#include "UnitVector3d.h"
 
 
namespace lsst {
namespace sphgeom {
 
class Circle : public Region {
public:
    static constexpr std::uint8_t TYPE_CODE = 'c';
 
    static Circle empty() { return Circle(); }
 
    static Circle full() { return Circle(UnitVector3d::Z(), 4.0); }
 
    static double squaredChordLengthFor(Angle openingAngle);
 
    static Angle openingAngleFor(double squaredChordLength);
 
    Circle() :
        _center(UnitVector3d::Z()),
        _squaredChordLength(-1.0),
        _openingAngle(-1.0)
    {}
 
    explicit Circle(UnitVector3d const & c) :
        _center(c),
        _squaredChordLength(0.0),
        _openingAngle(0.0)
    {}
 
    Circle(UnitVector3d const & c, Angle a) :
        _center(c),
        _squaredChordLength(squaredChordLengthFor(a)),
        _openingAngle(a)
    {}
 
    Circle(UnitVector3d const & c, double cl2) :
        _center(c),
        _squaredChordLength(cl2),
        _openingAngle(openingAngleFor(cl2))
    {}
 
    bool operator==(Circle const & c) const {
        return (isEmpty() && c.isEmpty()) ||
               (isFull() && c.isFull()) ||
               (_center == c._center &&
                _squaredChordLength == c._squaredChordLength &&
                _openingAngle == c._openingAngle);
    }
    bool operator!=(Circle const & c) const { return !(*this == c); }
 
    bool isEmpty() const {
        // Return true when _squaredChordLength is negative or NaN.
        return !(_squaredChordLength >= 0.0);
    }
 
    bool isFull() const { return _squaredChordLength >= 4.0; }
 
    UnitVector3d const & getCenter() const { return _center; }
 
    double getSquaredChordLength() const { return _squaredChordLength; }
 
    Angle getOpeningAngle() const { return _openingAngle; }
 
    bool contains(Circle const & x) const;
 
    bool isDisjointFrom(UnitVector3d const & x) const { return !contains(x); }
    bool isDisjointFrom(Circle const & x) const;
 
    bool intersects(UnitVector3d const & x) const { return contains(x); }
    bool intersects(Circle const & x) const { return !isDisjointFrom(x); }
 
    bool isWithin(UnitVector3d const &) const { return isEmpty(); }
    bool isWithin(Circle const & x) const { return x.contains(*this); }
 
    Circle & clipTo(UnitVector3d const & x);
    Circle & clipTo(Circle const & x);
 
    Circle clippedTo(UnitVector3d const & x) const {
        return Circle(*this).clipTo(x);
    }
 
    Circle clippedTo(Circle const & x) const {
        return Circle(*this).clipTo(x);
    }
 
    Circle & expandTo(UnitVector3d const & x);
    Circle & expandTo(Circle const & x);
 
    Circle expandedTo(UnitVector3d const & x) const {
        return Circle(*this).expandTo(x);
    }
 
    Circle expandedTo(Circle const & x) const {
        return Circle(*this).expandTo(x);
    }
 
    Circle & dilateBy(Angle r);
    Circle dilatedBy(Angle r) const { return Circle(*this).dilateBy(r); }
    Circle & erodeBy(Angle r) { return dilateBy(-r); }
    Circle erodedBy(Angle r) const { return dilatedBy(-r); }
 
    double getArea() const {
        return PI * std::max(0.0, std::min(_squaredChordLength, 4.0));
    }
 
    Circle & complement();
 
    Circle complemented() const { return Circle(*this).complement(); }
 
    Relationship relate(UnitVector3d const & v) const;
 
    // Region interface
    std::unique_ptr<Region> clone() const override {
        return std::unique_ptr<Circle>(new Circle(*this));
    }
 
    Box getBoundingBox() const override;
    Box3d getBoundingBox3d() const override;
    Circle getBoundingCircle() const override { return *this; }
 
    bool contains(UnitVector3d const & v) const override {
        return isFull() ||
               (v - _center).getSquaredNorm() <= _squaredChordLength;
    }
 
    using Region::contains;
 
    Relationship relate(Region const & r) const override {
        // Dispatch on the type of r.
        return invert(r.relate(*this));
    }
 
    Relationship relate(Box const &) const override;
    Relationship relate(Circle const &) const override;
    Relationship relate(ConvexPolygon const &) const override;
    Relationship relate(Ellipse const &) const override;
 
    std::vector<std::uint8_t> encode() const override;
 
    static std::unique_ptr<Circle> decode(std::vector<std::uint8_t> const & s) {
        return decode(s.data(), s.size());
    }
    static std::unique_ptr<Circle> decode(std::uint8_t const * buffer, size_t n);
 
private:
    static constexpr size_t ENCODED_SIZE = 41;
 
    UnitVector3d _center;
    double _squaredChordLength;
    Angle _openingAngle;
};
 
std::ostream & operator<<(std::ostream &, Circle const &);
 
}} // namespace lsst::sphgeom
 
#endif // LSST_SPHGEOM_CIRCLE_H_