minetest/src/light.h

/*
Minetest-c55
Copyright (C) 2010 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 General Public License as published by
the Free Software Foundation; either version 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#ifndef LIGHT_HEADER
#define LIGHT_HEADER

#include "common_irrlicht.h"

// This directly sets the range of light
#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)
		throw;
	
	return light_decode_table[light];
}

#endif