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/* ----------------------------------------------------------------------- *
 * This file is part of GEL, http://www.imm.dtu.dk/GEL
 * Copyright (C) the authors and DTU Informatics
 * For license and list of authors, see ../../doc/intro.pdf
 * ----------------------------------------------------------------------- */

/** @file TableTrigonometry.h
 * @brief Tabulated trigonometry - not certain this is useful.
 */

#ifndef __CGLA_TABLETRIGONOMETRY_H__
#define __CGLA_TABLETRIGONOMETRY_H__

#include <vector>
#include "CGLA.h"

namespace CGLA {

        namespace TableTrigonometry
        {
                typedef unsigned short int Angle;

                const Angle  ANGLE_MAX = USHRT_MAX>>2;
                const float ANGLE_FACTOR = float(ANGLE_MAX) / M_PI_2;
        
                class CosTable
                {
                        std::vector<float> tab;

                public:
                
                        CosTable(): tab(ANGLE_MAX+1)
                        {
                                for(int i=0;i<ANGLE_MAX+1; i++)
                                        tab[i] = cos(i/ANGLE_FACTOR);
                        }
                
                        float operator[](int i) const {return tab[i];}
                };

                const CosTable& COS_TABLE();

                inline float angle2float(Angle theta)
                {
                        static float MPI2 = (float)(M_PI * 2);
                        switch(theta & 3)
                                {
                                case 0: return   (theta>>2)/ANGLE_FACTOR;
                                case 1: return M_PI - (theta>>2)/ANGLE_FACTOR;
                                case 2: return M_PI + (theta>>2)/ANGLE_FACTOR;
                                case 3: return MPI2 - (theta>>2)/ANGLE_FACTOR;
                                }
                        return 0;       
                }

                inline float t_cos(Angle theta)
                {
                        switch(theta & 3)
                                {
                                case 0: return   COS_TABLE()[ theta>>2 ];
                                case 1: return - COS_TABLE()[ theta>>2 ];
                                case 2: return - COS_TABLE()[ theta>>2 ];
                                case 3: return   COS_TABLE()[ theta>>2 ];
                                }
                        return 0;
                }

                inline float t_sin(Angle theta)
                {
                        switch(theta & 3)
                                {
                                case 0: return   COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
                                case 1: return   COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
                                case 2: return - COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
                                case 3: return - COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
                                }
                        return 0;
                }

                inline Angle t_atan(float x, float y)
                {
                        Angle theta = Angle( acos(fabs(x)/sqrt(x*x+y*y)) * ANGLE_FACTOR );
                        Angle key = (x>=0 ? (y>=0 ? 0 : 3) : (y>=0 ? 1 : 2));
                        return (theta<<2) | key;
                }

        }


}
#endif