//C++ header - Open Scene Graph - Copyright (C) 1998-2001 Robert Osfield
//Distributed under the terms of the GNU Library General Public License (LGPL)
//as published by the Free Software Foundation.

#ifndef OSG_AUTOTRANSFORM
#define OSG_AUTOTRANSFORM 1

#include <osg/Group>
#include <osg/Matrix>

namespace osg {

/** AutoTransform - is group which all children
  * are transformed by a matrix which is automatically
  * calculated during the cull traversal.  The routine to
  * do the matrix transform is specified by the user allow
  * them customize its behavior to their own requirements.
*/
class SG_EXPORT AutoTransform : public Group
{
    public :
    
        class CalcTransformCallback : public osg::Referenced
        {
        
            public:
            
            /** Get the transformation matrix which moves from local coords to world coords.*/
            virtual const Matrix getLocalToWorldMatrix(const osg::Matrix& modelview) const = 0;

            /** Get the transformation matrix which moves from world coords to local coords.*/
            virtual const Matrix getWorldToLocalMatrix(const osg::Matrix& modelview) const = 0;
            
            protected:
            
            virtual ~CalcTransformCallback() {}
            
            
            
        };

        AutoTransform();

        /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
        AutoTransform(const AutoTransform&,const CopyOp& copyop=CopyOp::SHALLOW_COPY);

        AutoTransform(const Matrix& matix);

        META_Node(AutoTransform);

        /** Get the transformation matrix which moves from local coords to world coords.*/
        inline const Matrix getLocalToWorldMatrix(const osg::Matrix& modelview) const
        {
            if (_calcTransformCallback.valid())
                return _calcTransformCallback->getLocalToWorldMatrix(modelview);
            else return osg::Matrix::identity();
        }
        

        /** Get the transformation matrix which moves from world coords to local coords.*/
        inline const Matrix getWorldToLocalMatrix(const osg::Matrix& modelview) const
        {
            if (_calcTransformCallback.valid())
                return _calcTransformCallback->getLocalToWorldMatrix(modelview);
            else return osg::Matrix::identity();
        }
    

    protected :
    
        virtual ~AutoTransform();
        
        /** Override's Group's computeBound. 
          * There is no need to override in subclasses from osg::AutoTransform since this computeBound() uses 
          * the underlying matrix (calling computeMatrix if required.) */
        virtual const bool computeBound() const;
        
        ref_ptr<CalcTransformCallback> _calcTransformCallback;
};

}

#endif