/************************************************************************
* Minetest-c55
* Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
*
* light.h
* voxelands - 3d voxel world sandbox game
* Copyright (C) Lisa 'darkrose' Milne 2014 <lisa@ltmnet.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>
*
* License updated from GPLv2 or later to GPLv3 or later by Lisa Milne
* for Voxelands.
************************************************************************/

#ifndef LIGHT_HEADER
#define LIGHT_HEADER

#include "common_irrlicht.h"
#include "debug.h"

/*
	Day/night cache:
	Meshes are cached for different day-to-night transition values
*/

/*#define DAYNIGHT_CACHE_COUNT 3
// First one is day, last one is night.
extern u32 daynight_cache_ratios[DAYNIGHT_CACHE_COUNT];*/

/*
	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];

inline u8 decode_light(u8 light)
{
	if(light == LIGHT_SUN)
		return light_decode_table[LIGHT_MAX];

	if(light > LIGHT_MAX)
		light = LIGHT_MAX;

	return light_decode_table[light];
}

// 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;
}

#endif

