SpherePoint.h

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// -*- LSST-C++ -*-

/*
 * LSST Data Management System
 * See COPYRIGHT file at the top of the source tree.
 *
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * 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 LSST License Statement and
 * the GNU General Public License along with this program. If not,
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */

#ifndef LSST_AFW_GEOM_SPHEREPOINT_H_
#define LSST_AFW_GEOM_SPHEREPOINT_H_

#include <ostream>
#include <utility>

#include "lsst/afw/geom/Angle.h"
#include "lsst/afw/geom/Point.h"

namespace lsst {
namespace afw {
namespace geom {

class SpherePoint
#ifndef SWIG
        final
#endif
{
public:
    SpherePoint(Angle const& longitude, Angle const& latitude);

    explicit SpherePoint(Point3D const& vector);

    SpherePoint(SpherePoint const& other) noexcept;

    SpherePoint(SpherePoint&& other) noexcept;

    SpherePoint& operator=(SpherePoint const& other) noexcept;

    SpherePoint& operator=(SpherePoint&& other) noexcept;

    /*
     * Accessors
     */

    Angle getLongitude() const noexcept { return _longitude * radians; };

    Angle getLatitude() const noexcept { return _latitude * radians; };

    Point3D getVector() const noexcept;

    Angle operator[](size_t index) const;

    bool atPole() const noexcept {
        // Unit tests indicate we don't need to worry about epsilon-errors
        // Objects constructed from lat=90*degrees, <0,0,1>, etc. all have
        // atPole() = true. More complex operations like bearingTo have also
        // been tested near the poles with no ill effects
        return fabs(_latitude) >= HALFPI;
    }

    bool isFinite() const noexcept;

    /*
     * Comparisons between points
     */

    bool operator==(SpherePoint const& other) const noexcept;

    bool operator!=(SpherePoint const& other) const noexcept;

    Angle bearingTo(SpherePoint const& other) const;

    Angle separation(SpherePoint const& other) const noexcept;

    /*
     * Transformations of points
     */

    SpherePoint rotated(SpherePoint const& axis, Angle const& amount) const noexcept;

    SpherePoint offset(Angle const& bearing, Angle const& amount) const;

private:
    // For compatibility with Starlink AST, the implementation must be a
    // pair of floating-point numbers, with no other data. Do not change
    // the implementation without an RFC.
    double _longitude;  // radians
    double _latitude;   // radians
};

/*
 * Object-level display
 */

std::ostream& operator<<(std::ostream& os, SpherePoint const& point);
}
}
} /* namespace lsst::afw::geom */

#endif /* LSST_AFW_GEOM_SPHEREPOINT_H_ */