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/* ----------------------------------------------------------------------- *
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* This file is part of GEL, http://www.imm.dtu.dk/GEL
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* Copyright (C) the authors and DTU Informatics
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* For license and list of authors, see ../../doc/intro.pdf
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* ----------------------------------------------------------------------- */
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/** @file TableTrigonometry.h
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* @brief Tabulated trigonometry - not certain this is useful.
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*/
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#ifndef __CGLA_TABLETRIGONOMETRY_H__
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#define __CGLA_TABLETRIGONOMETRY_H__
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#include <vector>
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#include "CGLA.h"
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namespace CGLA {
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namespace TableTrigonometry
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{
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typedef unsigned short int Angle;
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const Angle ANGLE_MAX = USHRT_MAX>>2;
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const float ANGLE_FACTOR = float(ANGLE_MAX) / M_PI_2;
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class CosTable
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{
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std::vector<float> tab;
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public:
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CosTable(): tab(ANGLE_MAX+1)
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{
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for(int i=0;i<ANGLE_MAX+1; i++)
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tab[i] = cos(i/ANGLE_FACTOR);
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}
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float operator[](int i) const {return tab[i];}
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};
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const CosTable& COS_TABLE();
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inline float angle2float(Angle theta)
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{
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static float MPI2 = (float)(M_PI * 2);
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switch(theta & 3)
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{
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case 0: return (theta>>2)/ANGLE_FACTOR;
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case 1: return M_PI - (theta>>2)/ANGLE_FACTOR;
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case 2: return M_PI + (theta>>2)/ANGLE_FACTOR;
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case 3: return MPI2 - (theta>>2)/ANGLE_FACTOR;
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}
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return 0;
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}
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inline float t_cos(Angle theta)
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{
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switch(theta & 3)
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{
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case 0: return COS_TABLE()[ theta>>2 ];
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case 1: return - COS_TABLE()[ theta>>2 ];
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case 2: return - COS_TABLE()[ theta>>2 ];
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case 3: return COS_TABLE()[ theta>>2 ];
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}
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return 0;
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}
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inline float t_sin(Angle theta)
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{
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switch(theta & 3)
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{
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case 0: return COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
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case 1: return COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
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case 2: return - COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
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case 3: return - COS_TABLE()[ ANGLE_MAX - (theta>>2) ];
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}
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return 0;
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}
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inline Angle t_atan(float x, float y)
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{
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Angle theta = Angle( acos(fabs(x)/sqrt(x*x+y*y)) * ANGLE_FACTOR );
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Angle key = (x>=0 ? (y>=0 ? 0 : 3) : (y>=0 ? 1 : 2));
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return (theta<<2) | key;
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}
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}
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}
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#endif
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