/*]  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_

/**
 * \file sphere.hh
 * A round shape like a circle or sphere.
 * TODO: This class needs some work.
 */

#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>


namespace moof {


/**
 * A round object.
 */
template <int D = 3>
struct sphere : public cullable, public drawable, public shape<D>
{
	typedef moof::vector< scalar, 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 enclose_vertices(const vector vertices[], unsigned count);

	//void draw(scalar alpha = 0.0) const;
	//bool is_visible(const frustum& frustum) const;

	void enclose_vertices(const vector vertices[], unsigned count)
	{
		// TODO
	}

	void draw(scalar alpha = 0.0) const;

	bool is_visible(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 moof::ray<D>::contact& hit) const
	{
		vector b = point - ray.point;
		scalar z = dot(b, ray.direction);

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

		scalar d2 = 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>::is_visible(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 moof

#endif // _MOOF_SPHERE_HH_