src/Sine.h

   1 /*
   2  * Sine.h
   3  * Daniel Nelson - 8/24/0
   4  *
   5  * Copyright (C) 2000  Daniel Nelson
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2
  10  * of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  20  *
  21  * Daniel Nelson - aluminumangel.org
  22  * 174 W. 18th Ave.
  23  * Columbus, OH  43210
  24  */
  25
  26 #ifndef SINE_H
  27 #define SINE_H
  28
  29 #include "Game.h"
  30
  31 /* static */ class Sine {
  32 public:
  33   static void initialize (   );
  34
  35   static inline float sin ( float x )
  36   {
  37     int n = (int) ((x - GC_SINE_TABLE_LOWER_BOUND)
  38      * (1.0f / GC_SINE_TABLE_STEP_WIDTH));
  39
  40     if (n < 0) n = 0;
  41     if (n > GC_SINE_TABLE_LENGTH - 2) n = GC_SINE_TABLE_LENGTH - 2;
  42
  43     float remainder = x - GC_SINE_TABLE_LOWER_BOUND
  44      - n * GC_SINE_TABLE_STEP_WIDTH;
  45
  46     float estimate = table[n] + (table[n + 1] - table[n])
  47      * remainder * (1.0f / GC_SINE_TABLE_STEP_WIDTH);
  48
  49     return estimate;
  50   }
  51
  52   static float table[GC_SINE_TABLE_LENGTH];
  53 };
  54
  55 #endif