vcglib/vcg/space/sphere3.h

/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
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* 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      *
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* (at your option) any later version.                                       *
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* 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 (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
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/****************************************************************************
  History

$Log: not supported by cvs2svn $
Revision 1.5  2004/09/29 13:55:33  ponchio
Added Distance shpere - point.

Revision 1.4  2004/04/02 09:49:01  ponchio
Ehm... a couople of small errors.

Revision 1.3  2004/04/02 09:44:13  ponchio
Sphere ->Sphere3

Revision 1.2  2004/03/25 17:25:46  ponchio
#include sbagliato.

Revision 1.1  2004/03/21 17:51:57  ponchio
First version.


****************************************************************************/

#ifndef VCG_SPHERE_H
#define VCG_SPHERE_H

#include <vcg/space/point3.h>

namespace vcg {

/** \addtogroup space */
/*@{*/
/** 
Templated class for 3D sphere.
  This is the class for definition of a sphere in 3D space. It is stored just as a Point3 and a radius
	@param T (template parameter) Specifies the type of scalar used to represent coords.
  Various policy could be added to improve efficience (keeping square of radius for instance).
*/

template <class T> class Sphere3 {
protected:
  Point3<T> _center;
	T _radius;
public:
	Sphere3(): _radius(-1) {}
  Sphere3(const Point3<T> &center, T radius): _center(center), _radius(radius) {}

  T &Radius() { return _radius; }
  const T &Radius() const { return _radius; }
  Point3<T> &Center() { return _center; }
  const Point3<T> &Center() const { return _center; }

	bool IsEmpty() const { return _radius < 0; }
  ///return true if @param p - Center() <= Radius() 
  bool IsIn(const Point3<T> &p) const;

  void Add(Point3<T> &p);
	void Add(const Sphere3 &sphere);
  	
};

template <class T> T Distance(const Sphere3<T> &sphere, 
			      const Point3<T> &point) {
  T dist = Distance(point, sphere.Center()) - sphere.Radius();
  if(dist < 0) dist = 0;
  return dist;
}

template <class T> T Distance(const Sphere3<T> &sphere, 
			      const Sphere3<T> &s) {
  T dist = Distance(s.Center(), sphere.Center()) 
                    - sphere.Radius() - s.Radius();
  if(dist < 0) dist = 0;
  return dist;
}

typedef Sphere3<float> Sphere3f;
typedef Sphere3<double> Sphere3d;

template <class T> void Sphere3<T>::Add(const Sphere3<T> &sphere) {
  if(IsEmpty()) {
			*this = sphere;
			return;
		}
		Point3<T> dist = sphere.Center() - _center;
    float distance = dist.Norm();
		float fartest = distance + sphere.Radius();

		if(fartest <= _radius) 
      return;
    if(distance == 0) 
      _radius = sphere.Radius();
    else {
	    _center += dist * ((fartest - _radius) / (dist.Norm() * 2));
		  _radius = (_radius + fartest)/2;
    }
}

template <class T> void Sphere3<T>::Add(Point3<T> &p) {
	if(IsEmpty()) {
		_center = p;
		_radius = 0;
	}
	Point3<T> dist = p - _center;
	float fartest = dist.Norm();
	if(fartest <= _radius) return;
	_center += dist * ((fartest - _radius) / (fartest*2));
	_radius = (_radius + fartest)/2;
}  

template <class T> bool Sphere3<T>::IsIn(const Point3<T> &p) const {
	Point3<T> dist = p - _center;
	return dist.Norm() <= _radius;
}

} //namespace


#endif