luanti/src/light.cpp

/*
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 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.
*/

#include "light.h"

#if 1
// Middle-raised variation of a_n+1 = a_n * 0.786
// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
// LIGHT_SUN is read as LIGHT_MAX from here.
u8 light_decode_table[LIGHT_MAX+1] = 
{
8,
11+2,
14+7,
18+10,
22+15,
29+20,
37+20,
47+15,
60+10,
76+7,
97+5,
123+2,
157,
200,
255,
};
#endif

#if 0
/*
Made using this and:
- adding 220 as the second last one
- replacing the third last one (212) with 195

#!/usr/bin/python

from math import *
from sys import stdout

# We want 0 at light=0 and 255 at light=LIGHT_MAX
LIGHT_MAX = 14
#FACTOR = 0.69
#FACTOR = 0.75
FACTOR = 0.83
START_FROM_ZERO = False

L = []
if START_FROM_ZERO:
    for i in range(1,LIGHT_MAX+1):
        L.append(int(round(255.0 * FACTOR ** (i-1))))
    L.append(0)
else:
    for i in range(1,LIGHT_MAX+1):
        L.append(int(round(255.0 * FACTOR ** (i-1))))
    L.append(255)

L.reverse()
for i in L:
    stdout.write(str(i)+",\n")
*/
u8 light_decode_table[LIGHT_MAX+1] = 
{
23,
27,
33,
40,
48,
57,
69,
83,
100,
121,
146,
176,
195,
220,
255,
};
#endif

#if 0
// This is good
// a_n+1 = a_n * 0.786
// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
// LIGHT_SUN is read as LIGHT_MAX from here.
u8 light_decode_table[LIGHT_MAX+1] = 
{
8,
11,
14,
18,
22,
29,
37,
47,
60,
76,
97,
123,
157,
200,
255,
};
#endif

#if 0
// Use for debugging in dark
u8 light_decode_table[LIGHT_MAX+1] = 
{
58,
64,
72,
80,
88,
98,
109,
121,
135,
150,
167,
185,
206,
229,
255,
};
#endif

// This is reasonable with classic lighting with a light source
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
2,
3,
4,
6,
9,
13,
18,
25,
32,
35,
45,
57,
69,
79,
255
};*/


// As in minecraft, a_n+1 = a_n * 0.8
// NOTE: This doesn't really work that well because this defines
//       LIGHT_MAX as dimmer than LIGHT_SUN
// NOTE: Uh, this has had 34 left out; forget this.
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
8,
11,
14,
17,
21,
27,
42,
53,
66,
83,
104,
130,
163,
204,
255,
};*/

// This was a quick try of more light, manually quickly made
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
7,
11,
15,
21,
29,
42,
53,
69,
85,
109,
135,
167,
205,
255,
};*/

// This was used for a long time, manually made
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
6,
8,
11,
14,
19,
26,
34,
45,
61,
81,
108,
143,
191,
255,
};*/

/*u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
3,
6,
10,
18,
25,
35,
50,
75,
95,
120,
150,
185,
215,
255,
};*/
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
5,
12,
22,
35,
50,
65,
85,
100,
120,
140,
160,
185,
215,
255,
};*/
// LIGHT_MAX is 14, 0-14 is 15 values
/*u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
9,
12,
14,
16,
20,
26,
34,
45,
61,
81,
108,
143,
191,
255,
};*/

#if 0
/*
#!/usr/bin/python

from math import *
from sys import stdout

# We want 0 at light=0 and 255 at light=LIGHT_MAX
LIGHT_MAX = 14
#FACTOR = 0.69
FACTOR = 0.75

L = []
for i in range(1,LIGHT_MAX+1):
    L.append(int(round(255.0 * FACTOR ** (i-1))))
L.append(0)

L.reverse()
for i in L:
    stdout.write(str(i)+",\n")
*/
u8 light_decode_table[LIGHT_MAX+1] = 
{
0,
6,
8,
11,
14,
19,
26,
34,
45,
61,
81,
108,
143,
191,
255,
};
#endif