OgreSphere.h

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/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2012 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef __Sphere_H_
#define __Sphere_H_

// Precompiler options
#include "OgrePrerequisites.h"

#include "OgreVector3.h"

namespace Ogre {


    class _OgreExport Sphere
    {
    protected:
        Real mRadius;
        Vector3 mCenter;
    public:
        Sphere() : mRadius(1.0), mCenter(Vector3::ZERO) {}
        Sphere(const Vector3& center, Real radius)
            : mRadius(radius), mCenter(center) {}

        Real getRadius(void) const { return mRadius; }

        void setRadius(Real radius) { mRadius = radius; }

        const Vector3& getCenter(void) const { return mCenter; }

        void setCenter(const Vector3& center) { mCenter = center; }

        bool intersects(const Sphere& s) const
        {
            return (s.mCenter - mCenter).squaredLength() <=
                Math::Sqr(s.mRadius + mRadius);
        }
        bool intersects(const AxisAlignedBox& box) const
        {
            return Math::intersects(*this, box);
        }
        bool intersects(const Plane& plane) const
        {
            return Math::intersects(*this, plane);
        }
        bool intersects(const Vector3& v) const
        {
            return ((v - mCenter).squaredLength() <= Math::Sqr(mRadius));
        }
        void merge(const Sphere& oth)
        {
            Vector3 diff =  oth.getCenter() - mCenter;
            Real lengthSq = diff.squaredLength();
            Real radiusDiff = oth.getRadius() - mRadius;
            
            // Early-out
            if (Math::Sqr(radiusDiff) >= lengthSq) 
            {
                // One fully contains the other
                if (radiusDiff <= 0.0f) 
                    return; // no change
                else 
                {
                    mCenter = oth.getCenter();
                    mRadius = oth.getRadius();
                    return;
                }
            }
            
            Real length = Math::Sqrt(lengthSq);
            
            Vector3 newCenter;
            Real newRadius;
            if ((length + oth.getRadius()) > mRadius) 
            {
                Real t = (length + radiusDiff) / (2.0f * length);
                newCenter = mCenter + diff * t;
            } 
            // otherwise, we keep our existing center
            
            newRadius = 0.5f * (length + mRadius + oth.getRadius());
            
            mCenter = newCenter;
            mRadius = newRadius;
        }
        

    };
}

#endif