OpenSceneGraph/include/osg/BoundingSphere

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library 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 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_BOUNDINGSPHERE
#define OSG_BOUNDINGSPHERE 1

#include <osg/Export>
#include <osg/Vec3>

namespace osg {

class BoundingBox;

/** General purpose bounding sphere class for enclosing nodes/objects/vertices.
  * Bounds internal osg::Nodes in the scene, assists in view frustum culling,
  * etc. Similar in function to BoundingBox, it's quicker for evaluating
  * culling but generally will not cull as aggressively because it encloses a
  * greater volume.
*/
class SG_EXPORT BoundingSphere
{
    public:
        
        Vec3 _center;
        float _radius;

        /** Construct a default bounding sphere with radius to -1.0f, representing an invalid/unset bounding sphere.*/ 
        BoundingSphere() : _center(0.0f,0.0f,0.0f),_radius(-1.0f) {}
    
        /** Creates a bounding sphere initialized to the given extents. */
        BoundingSphere(const Vec3& center,float radius) : _center(center),_radius(radius) {}

        /** Clear the bounding sphere. Reset to default values. */
        inline void init()
        {
            _center.set(0.0f,0.0f,0.0f);
            _radius = -1.0f;
        }

        /** Returns true of the bounding sphere extents are valid, false
          * otherwise. */
        inline bool valid() const { return _radius>=0.0f; }

        /** Set the bounding sphere to the given center/radius. */ 
        inline void set(const Vec3& center,float radius)
        {
            _center = center;
            _radius = radius;
        }

        /** Returns the center of the bounding sphere. */
        inline Vec3& center() { return _center; }
        /** Returns the const center of the bounding sphere. */
        inline const Vec3& center() const { return _center; }

        /** Returns the radius of the bounding sphere. */
        inline float& radius() { return _radius; }
        /** Returns the const radius of the bounding sphere. */
        inline float radius() const { return _radius; }
        
        /** Returns the squared length of the radius. Note, For performance
          * reasons, the calling method is responsible for checking to make
          * sure the sphere is valid. */
        inline float radius2() const { return _radius*_radius; }

        /** Expands the sphere to encompass the given point. Repositions the
          * sphere center to minimize the radius increase. If the sphere is
          * uninitialized, set its center to v and radius to zero. */
        void expandBy(const Vec3& v);

        /** Expands the sphere to encompass the given point. Does not
          * reposition the sphere center. If the sphere is
          * uninitialized, set its center to v and radius to zero. */
        void expandRadiusBy(const Vec3& v);

        /** Expands the sphere to encompass the given sphere. Repositions the
          * sphere center to minimize the radius increase. If the sphere is
          * uninitialized, set its center and radius to match sh. */
        void expandBy(const BoundingSphere& sh);

        /** Expands the sphere to encompass the given sphere. Does not
          * repositions the sphere center. If the sphere is
          * uninitialized, set its center and radius to match sh. */
        void expandRadiusBy(const BoundingSphere& sh);

        /** Expands the sphere to encompass the given box. Repositions the
          * sphere center to minimize the radius increase. */
        void expandBy(const BoundingBox& bb);

        /** Expands the sphere to encompass the given box. Does not
          * repositions the sphere center. */
        void expandRadiusBy(const BoundingBox& bb);

        /** Returns true if v is within the sphere. */
        inline bool contains(const Vec3& v) const
        {
            return valid() && ((v-_center).length2()<=radius2());
        }

        /** Returns true if there is a non-empty intersection with the given
          * bounding sphere. */
        inline bool intersects( const BoundingSphere& bs ) const
        {
            return valid() && bs.valid() &&
                   ((_center - bs._center).length2() <= (_radius + bs._radius)*(_radius + bs._radius));
        }

};

}

#endif