src/daynightratio.h

   1 /*
   2 Minetest
   3 Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #ifndef DAYNIGHTRATIO_HEADER
  21 #define DAYNIGHTRATIO_HEADER
  22
  23 inline u32 time_to_daynight_ratio(float time_of_day, bool smooth)
  24 {
  25         float t = time_of_day;
  26         if(t < 0)
  27                 t += ((int)(-t)/24000)*24000;
  28         if(t >= 24000)
  29                 t -= ((int)(t)/24000)*24000;
  30         if(t > 12000)
  31                 t = 24000 - t;
  32         float values[][2] = {
  33                 {4250+125, 150},
  34                 {4500+125, 150},
  35                 {4750+125, 250},
  36                 {5000+125, 350},
  37                 {5250+125, 500},
  38                 {5500+125, 675},
  39                 {5750+125, 875},
  40                 {6000+125, 1000},
  41                 {6250+125, 1000},
  42         };
  43         if(!smooth){
  44                 float lastt = values[0][0];
  45                 for(u32 i=1; i<sizeof(values)/sizeof(*values); i++){
  46                         float t0 = values[i][0];
  47                         float switch_t = (t0 + lastt) / 2;
  48                         lastt = t0;
  49                         if(switch_t <= t)
  50                                 continue;
  51                         return values[i][1];
  52                 }
  53                 return 1000;
  54         } else {
  55                 for(u32 i=0; i<sizeof(values)/sizeof(*values); i++){
  56                         if(values[i][0] <= t)
  57                                 continue;
  58                         if(i == 0)
  59                                 return values[i][1];
  60                         float td0 = values[i][0] - values[i-1][0];
  61                         float f = (t - values[i-1][0]) / td0;
  62                         return f * values[i][1] + (1.0 - f) * values[i-1][1];
  63                 }
  64                 return 1000;
  65         }
  66 }
  67
  68 #endif
  69