light.h

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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.
*/
 
#pragma once
#include <cassert>
#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.
// If changed, this constant as defined in builtin/game/constants.lua must
// also be changed.
#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
 
#ifndef SERVER
 
extern const u8 *light_decode_table;
 
// 0 <= light <= LIGHT_SUN
// 0 <= return value <= 255
inline u8 decode_light(u8 light)
{
    // assert(light <= LIGHT_SUN);
    if (light > LIGHT_SUN)
        light = LIGHT_SUN;
    return light_decode_table[light];
}
 
// 0.0 <= light <= 1.0
// 0.0 <= return value <= 1.0
float decode_light_f(float light_f);
 
void set_light_table(float gamma);
 
#endif // ifndef SERVER
 
// 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;
}