// ball.h (A n-dimensional ball)
//
//  The WorldForge Project
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//
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//  it under the terms of the GNU General Public License as published by
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// Author: Ron Steinke

#ifndef WFMATH_BALL_H
#define WFMATH_BALL_H

#include <wfmath/point.h>
#include <wfmath/intersect_decls.h>

namespace WFMath {

template<int dim>
class Ball;

/// get the minimal bounding sphere for a set of points
template<int dim, template<class, class> class container>
Ball<dim> BoundingSphere(const container<Point<dim>, std::allocator<Point<dim> > >& c);

/// get a bounding sphere for a set of points
template<int dim, template<class, class> class container>
Ball<dim> BoundingSphereSloppy(const container<Point<dim>, std::allocator<Point<dim> > >& c);

template<int dim>
std::ostream& operator<<(std::ostream& os, const Ball<dim>& m);

template<int dim>
std::istream& operator>>(std::istream& is, Ball<dim>& m);

/// A dim dimensional ball
/**
 * This class implements the full shape interface, as described in
 * the fake class Shape.
 *
 * This class is called Ball<> instead of Sphere to be more in tune
 * with the usual mathematical naming conventions, where a ball is
 * a filled object, while a sphere is just the outer shell. It also
 * helps that a Ball<n> corresponds to an n-ball, while a Sphere<n>
 * would correspond to an (n-1)-sphere.
 **/
template<int dim = 3>
class Ball {
public:
	/// construct an uninitialized ball
	Ball() : m_center{}, m_radius(0) {}

	/// construct a ball with the given center and radius
	Ball(const Point<dim>& center, CoordType radius)
			: m_center(center), m_radius(radius) { if (radius < 0) m_center.setValid(false); }

	/// construct a copy of a ball
	Ball(const Ball& b) = default;

	/// Construct a ball from an object passed by Atlas
	explicit Ball(const AtlasInType& a);

	~Ball() = default;

	friend std::ostream& operator<<<dim>(std::ostream& os, const Ball& b);

	friend std::istream& operator>><dim>(std::istream& is, Ball& b);

	/// Create an Atlas object from the box
	AtlasOutType toAtlas() const;

	/// Set the box's value to that given by an Atlas object
	void fromAtlas(const AtlasInType& a);

	Ball& operator=(const Ball& b) = default;

	bool isEqualTo(const Ball& b, CoordType epsilon = numeric_constants<CoordType>::epsilon()) const;

	bool operator==(const Ball& b) const { return isEqualTo(b); }

	bool operator!=(const Ball& b) const { return !isEqualTo(b); }

	bool isValid() const { return m_center.isValid(); }

	// Descriptive characteristics

	size_t numCorners() const { return 0; }

	// This next function exists so that Ball can be used by code
	// that finds the number of corners with numCorners(), and does something
	// with each corner with getCorner(). No idea how useful that is, but
	// it's not a particularly complicated function to write.
	Point<dim> getCorner(size_t) const { return m_center; }

	Point<dim> getCenter() const { return m_center; }

	/// get the center of the ball
	const Point<dim>& center() const { return m_center; }

	/// get the center of the ball
	Point<dim>& center() { return m_center; }

	/// get the radius of the ball
	CoordType radius() const { return m_radius; }

	/// get the radius of the ball
	CoordType& radius() { return m_radius; }

	// Movement functions

	Ball& shift(const Vector<dim>& v) {
		m_center += v;
		return *this;
	}

	Ball& moveCornerTo(const Point<dim>&, size_t) { return *this; }

	Ball& moveCenterTo(const Point<dim>& p) {
		m_center = p;
		return *this;
	}

	Ball& rotateCorner(const RotMatrix<dim>&, size_t) { return *this; }

	Ball& rotateCenter(const RotMatrix<dim>&) { return *this; }

	Ball& rotatePoint(const RotMatrix<dim>& m, const Point<dim>& p) {
		m_center.rotate(m, p);
		return *this;
	}

	// 3D rotation function
	Ball& rotateCorner(const Quaternion&, size_t corner);

	Ball& rotateCenter(const Quaternion&);

	Ball& rotatePoint(const Quaternion& q, const Point<dim>& p);

	// Intersection functions

	AxisBox<dim> boundingBox() const;

	Ball boundingSphere() const { return *this; }

	Ball boundingSphereSloppy() const { return *this; }

	Ball toParentCoords(const Point<dim>& origin,
						const RotMatrix<dim>& rotation = RotMatrix<dim>().identity()) const { return Ball(m_center.toParentCoords(origin, rotation), m_radius); }

	Ball toParentCoords(const AxisBox<dim>& coords) const { return Ball(m_center.toParentCoords(coords), m_radius); }

	Ball toParentCoords(const RotBox<dim>& coords) const { return Ball(m_center.toParentCoords(coords), m_radius); }

	// toLocal is just like toParent, expect we reverse the order of
	// translation and rotation and use the opposite sense of the rotation
	// matrix

	Ball toLocalCoords(const Point<dim>& origin,
					   const RotMatrix<dim>& rotation = RotMatrix<dim>().identity()) const { return Ball(m_center.toLocalCoords(origin, rotation), m_radius); }

	Ball toLocalCoords(const AxisBox<dim>& coords) const { return Ball(m_center.toLocalCoords(coords), m_radius); }

	Ball toLocalCoords(const RotBox<dim>& coords) const { return Ball(m_center.toLocalCoords(coords), m_radius); }

	// 3D only
	Ball toParentCoords(const Point<dim>& origin, const Quaternion& rotation) const;

	Ball toLocalCoords(const Point<dim>& origin, const Quaternion& rotation) const;

	friend bool Intersect<dim>(const Ball& b, const Point<dim>& p, bool proper);

	friend bool Contains<dim>(const Point<dim>& p, const Ball& b, bool proper);

	friend bool Intersect<dim>(const Ball& b, const AxisBox<dim>& a, bool proper);

	friend bool Contains<dim>(const Ball& b, const AxisBox<dim>& a, bool proper);

	friend bool Contains<dim>(const AxisBox<dim>& a, const Ball& b, bool proper);

	friend bool Intersect<dim>(const Ball& b1, const Ball& b2, bool proper);

	friend bool Contains<dim>(const Ball& outer, const Ball& inner, bool proper);

	friend bool Intersect<dim>(const Segment<dim>& s, const Ball& b, bool proper);

	friend bool Contains<dim>(const Segment<dim>& s, const Ball& b, bool proper);

	friend bool Intersect<dim>(const RotBox<dim>& r, const Ball& b, bool proper);

	friend bool Contains<dim>(const RotBox<dim>& r, const Ball& b, bool proper);

	friend bool Contains<dim>(const Ball& b, const RotBox<dim>& r, bool proper);

	friend bool Intersect<dim>(const Polygon<dim>& p, const Ball& b, bool proper);

	friend bool Contains<dim>(const Polygon<dim>& p, const Ball& b, bool proper);

	friend bool Contains<dim>(const Ball& b, const Polygon<dim>& p, bool proper);

private:

	Point<dim> m_center;
	CoordType m_radius;
};

template<int dim>
inline bool Ball<dim>::isEqualTo(const Ball<dim>& b, CoordType epsilon) const {
	return Equal(m_center, b.m_center, epsilon)
		   && Equal(m_radius, b.m_radius, epsilon);
}

} // namespace WFMath

#endif  // WFMATH_BALL_H
