mirror of https://github.com/minetest/minetest.git
130 lines
3.2 KiB
C
130 lines
3.2 KiB
C
/*
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Minetest
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Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef LIGHT_HEADER
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#define LIGHT_HEADER
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#include "irrlichttypes.h"
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#include "debug.h"
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/*
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Day/night cache:
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Meshes are cached for different day-to-night transition values
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*/
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/*#define DAYNIGHT_CACHE_COUNT 3
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// First one is day, last one is night.
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extern u32 daynight_cache_ratios[DAYNIGHT_CACHE_COUNT];*/
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/*
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Lower level lighting stuff
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*/
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// This directly sets the range of light.
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// Actually this is not the real maximum, and this is not the
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// brightest. The brightest is LIGHT_SUN.
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#define LIGHT_MAX 14
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// Light is stored as 4 bits, thus 15 is the maximum.
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// This brightness is reserved for sunlight
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#define LIGHT_SUN 15
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inline u8 diminish_light(u8 light)
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{
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if(light == 0)
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return 0;
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if(light >= LIGHT_MAX)
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return LIGHT_MAX - 1;
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return light - 1;
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}
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inline u8 diminish_light(u8 light, u8 distance)
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{
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if(distance >= light)
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return 0;
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return light - distance;
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}
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inline u8 undiminish_light(u8 light)
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{
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// We don't know if light should undiminish from this particular 0.
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// Thus, keep it at 0.
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if(light == 0)
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return 0;
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if(light == LIGHT_MAX)
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return light;
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return light + 1;
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}
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extern u8 light_decode_table[LIGHT_MAX+1];
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// 0 <= light <= LIGHT_SUN
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// 0 <= return value <= 255
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inline u8 decode_light(u8 light)
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{
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if(light > LIGHT_MAX)
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light = LIGHT_MAX;
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return light_decode_table[light];
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}
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// 0.0 <= light <= 1.0
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// 0.0 <= return value <= 1.0
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inline float decode_light_f(float light_f)
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{
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s32 i = (u32)(light_f * LIGHT_MAX + 0.5);
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if(i <= 0)
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return (float)light_decode_table[0] / 255.0;
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if(i >= LIGHT_MAX)
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return (float)light_decode_table[LIGHT_MAX] / 255.0;
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float v1 = (float)light_decode_table[i-1] / 255.0;
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float v2 = (float)light_decode_table[i] / 255.0;
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float f0 = (float)i - 0.5;
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float f = light_f * LIGHT_MAX - f0;
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return f * v2 + (1.0 - f) * v1;
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}
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// 0 <= daylight_factor <= 1000
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// 0 <= lightday, lightnight <= LIGHT_SUN
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// 0 <= return value <= LIGHT_SUN
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inline u8 blend_light(u32 daylight_factor, u8 lightday, u8 lightnight)
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{
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u32 c = 1000;
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u32 l = ((daylight_factor * lightday + (c-daylight_factor) * lightnight))/c;
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if(l > LIGHT_SUN)
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l = LIGHT_SUN;
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return l;
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}
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// 0.0 <= daylight_factor <= 1.0
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// 0 <= lightday, lightnight <= LIGHT_SUN
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// 0 <= return value <= 255
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inline u8 blend_light_f1(float daylight_factor, u8 lightday, u8 lightnight)
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{
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u8 l = ((daylight_factor * decode_light(lightday) +
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(1.0-daylight_factor) * decode_light(lightnight)));
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return l;
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}
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#endif
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