/*]  Copyright (c) 2009-2010, Charles McGarvey  [**************************
**]  All rights reserved.
*
* vi:ts=4 sw=4 tw=75
*
* Distributable under the terms and conditions of the 2-clause BSD license;
* see the file COPYING for a complete text of the license.
*
**************************************************************************/

#ifndef _MOOF_SPHERE_HH_
#define _MOOF_SPHERE_HH_

#include <Moof/Contact.hh>
#include <Moof/Cullable.hh>
#include <Moof/Drawable.hh>
#include <Moof/Frustum.hh>
#include <Moof/Math.hh>
#include <Moof/OpenGL.hh>
#include <Moof/Shape.hh>

// TODO this needs work

namespace Mf {


/**
 * A round object.
 */


template <int D = 3>
struct Sphere : public Cullable, public Drawable, public Shape<D>
{
	typedef cml::vector< Scalar, cml::fixed<D> >	Vector;

	Vector	point;
	Scalar	radius;


	Sphere() {}

	Sphere(const Vector& p, Scalar r) :
		point(p),
		radius(r) {}


	void init(const Vector& p, Scalar r)
	{
		point = p;
		radius = r;
	}

	void init(const Vector& p, const Vector& o)
	{
		point = p;
		radius = (o - p).length();
	}

	//void encloseVertices(const Vector vertices[], unsigned count);

	//void draw(Scalar alpha = 0.0) const;
	//bool isVisible(const Frustum& frustum) const;

	void encloseVertices(const Vector vertices[], unsigned count)
	{
		// TODO
	}

	void draw(Scalar alpha = 0.0) const;

	bool isVisible(const Frustum& frustum) const
	{
		return true;
	}


	bool intersect(const Sphere<D>& sphere, Contact<D>& hit) const
	{
		Vector n = sphere.point - point;
		Scalar distance = n.length();
		Scalar limit = radius + sphere.radius;

		if (distance > limit) return false;

		hit.normal = n.normalize();
		hit.distance = limit - distance;
		hit.point = hit.normal * radius;

		return true;
	}

	bool intersect(const Vector& point2, Contact<D>& hit) const
	{
		Vector n = point2 - point;
		Scalar distance = n.length();

		if (distance > radius) return false;

		hit.normal = n.normalize();
		hit.distance = radius - distance;
		hit.point = point2;

		return true;
	}

	// a ray inside the sphere will not intersect on its way out
	bool intersect(const Ray<D>& ray, typename Ray<D>::Contact& hit) const
	{
		Vector b = point - ray.point;
		Scalar z = cml::dot(b, ray.direction);

		// check if the ball is behind the ray
		if (z < SCALAR(0.0)) return false;

		Scalar d2 = cml::dot(b, b) - z*z;
		Scalar r2 = radius * radius;

		// check for an intersection
		if (d2 > r2) return false;

		hit.distance = z - std::sqrt(r2 - d2);
		if (hit.distance < SCALAR(0.0)) return false;

		Vector surfacePoint;
		ray.solve(surfacePoint, hit.distance);
		hit.normal = surfacePoint - point;
		return true;
	}
};


template <>
inline bool Sphere<3>::isVisible(const Frustum& frustum) const
{
	return frustum.contains(*this);
}

template <>
inline void Sphere<2>::draw(Scalar alpha) const
{
	GLUquadricObj* sphereObj = gluNewQuadric();
	gluQuadricDrawStyle(sphereObj, GLU_LINE);

	glPushMatrix();

	glTranslate(promote(point));
	gluSphere(sphereObj, GLdouble(radius), 16, 16);

	glPopMatrix();

	gluDeleteQuadric(sphereObj);
}

template <>
inline void Sphere<3>::draw(Scalar alpha) const
{
	GLUquadricObj* sphereObj = gluNewQuadric();
	gluQuadricDrawStyle(sphereObj, GLU_LINE);

	glPushMatrix();

	glTranslate(point);
	gluSphere(sphereObj, GLdouble(radius), 16, 16);

	glPopMatrix();

	gluDeleteQuadric(sphereObj);
}

template <int D>
inline bool checkCollision(const Sphere<D>& a, const Sphere<D>& b)
{
	Scalar d = (a.point - b.point).length();
	return d < (a.radius + b.radius);
}


typedef Sphere<2>	Sphere2;
typedef Sphere2 	Circle;
typedef Sphere<3>	Sphere3;


} // namespace Mf

#endif // _MOOF_SPHERE_HH_