src/light.h

   1 /************************************************************************
   2 * Minetest-c55
   3 * Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
   4 *
   5 * light.h
   6 * voxelands - 3d voxel world sandbox game
   7 * Copyright (C) Lisa 'darkrose' Milne 2014 <lisa@ltmnet.com>
   8 *
   9 * This program is free software: you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation, either version 3 of the License, or
  12 * (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful, but
  15 * WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  17 * See the GNU General Public License for more details.
  18 *
  19 * You should have received a copy of the GNU General Public License
  20 * along with this program.  If not, see <http://www.gnu.org/licenses/>
  21 *
  22 * License updated from GPLv2 or later to GPLv3 or later by Lisa Milne
  23 * for Voxelands.
  24 ************************************************************************/
  25
  26 #ifndef LIGHT_HEADER
  27 #define LIGHT_HEADER
  28
  29 #include "common_irrlicht.h"
  30 #include "debug.h"
  31
  32 /*
  33         Day/night cache:
  34         Meshes are cached for different day-to-night transition values
  35 */
  36
  37 /*#define DAYNIGHT_CACHE_COUNT 3
  38 // First one is day, last one is night.
  39 extern u32 daynight_cache_ratios[DAYNIGHT_CACHE_COUNT];*/
  40
  41 /*
  42         Lower level lighting stuff
  43 */
  44
  45 // This directly sets the range of light.
  46 // Actually this is not the real maximum, and this is not the
  47 // brightest. The brightest is LIGHT_SUN.
  48 #define LIGHT_MAX 14
  49 // Light is stored as 4 bits, thus 15 is the maximum.
  50 // This brightness is reserved for sunlight
  51 #define LIGHT_SUN 15
  52
  53 // these are used in mob spawning
  54 #define LIGHT_SPAWN_BRIGHT 10
  55 #define LIGHT_SPAWN_DARK 4
  56
  57 inline u8 diminish_light(u8 light)
  58 {
  59         if(light == 0)
  60                 return 0;
  61         if(light >= LIGHT_MAX)
  62                 return LIGHT_MAX - 1;
  63
  64         return light - 1;
  65 }
  66
  67 inline u8 diminish_light(u8 light, u8 distance)
  68 {
  69         if(distance >= light)
  70                 return 0;
  71         return  light - distance;
  72 }
  73
  74 inline u8 undiminish_light(u8 light)
  75 {
  76         // We don't know if light should undiminish from this particular 0.
  77         // Thus, keep it at 0.
  78         if(light == 0)
  79                 return 0;
  80         if(light == LIGHT_MAX)
  81                 return light;
  82
  83         return light + 1;
  84 }
  85
  86 extern u8 light_decode_table[LIGHT_MAX+1];
  87
  88 inline u8 decode_light(u8 light)
  89 {
  90         if(light == LIGHT_SUN)
  91                 return light_decode_table[LIGHT_MAX];
  92
  93         if(light > LIGHT_MAX)
  94                 light = LIGHT_MAX;
  95
  96         return light_decode_table[light];
  97 }
  98
  99 // 0 <= daylight_factor <= 1000
 100 // 0 <= lightday, lightnight <= LIGHT_SUN
 101 // 0 <= return value <= LIGHT_SUN
 102 inline u8 blend_light(u32 daylight_factor, u8 lightday, u8 lightnight)
 103 {
 104         u32 c = 1000;
 105         u32 l = ((daylight_factor * lightday + (c-daylight_factor) * lightnight))/c;
 106         if(l > LIGHT_SUN)
 107                 l = LIGHT_SUN;
 108         return l;
 109 }
 110
 111 #endif
 112