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