mirror of
https://github.com/moparisthebest/minetest
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389 lines
5.4 KiB
C++
389 lines
5.4 KiB
C++
/*
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Minetest
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Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "light.h"
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#include <math.h>
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#include "util/numeric.h"
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#ifndef SERVER
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// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
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// LIGHT_SUN is read as LIGHT_MAX from here.
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u8 light_LUT[LIGHT_MAX+1] =
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{
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/* Middle-raised variation of a_n+1 = a_n * 0.786
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* Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
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* LIGHT_SUN is read as LIGHT_MAX from here.
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*/
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8,
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11+2,
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14+7,
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18+10,
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22+15,
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29+20,
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37+20,
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47+15,
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60+10,
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76+7,
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97+5,
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123+2,
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157,
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200,
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255,
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};
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const u8 *light_decode_table = light_LUT;
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/** Initialize or update the light value tables using the specified \p gamma.
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* If \p gamma == 1.0 then the light table is linear. Typically values for
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* gamma range between 1.8 and 2.2.
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*
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* @note The value for gamma will be restricted to the range 1.1 <= gamma <= 3.0.
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*
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* @note This function is not, currently, a simple linear to gamma encoding
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* because adjustments are made so that a gamma of 1.8 gives the same
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* results as those hardcoded for use by the server.
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*/
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void set_light_table(float gamma)
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{
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static const float brightness_step = 255.0f / (LIGHT_MAX + 1);
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/* These are adjustment values that are added to the calculated light value
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* after gamma is applied. Currently they are used so that given a gamma
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* of 1.8 the light values set by this function are the same as those
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* hardcoded in the initalizer list for the declaration of light_LUT.
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*/
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static const int adjustments[LIGHT_MAX + 1] = {
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7,
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7,
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7,
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5,
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2,
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0,
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-7,
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-20,
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-31,
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-39,
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-43,
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-45,
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-40,
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-25,
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0
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};
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gamma = rangelim(gamma, 1.1, 3.0);
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float brightness = brightness_step;
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for (size_t i = 0; i < LIGHT_MAX; i++) {
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light_LUT[i] = (u8)(255 * powf(brightness / 255.0f, gamma));
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light_LUT[i] = rangelim(light_LUT[i] + adjustments[i], 0, 255);
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if (i > 1 && light_LUT[i] < light_LUT[i-1])
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light_LUT[i] = light_LUT[i-1] + 1;
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brightness += brightness_step;
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}
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light_LUT[LIGHT_MAX] = 255;
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}
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#endif
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#if 0
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/*
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Made using this and:
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- adding 220 as the second last one
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- replacing the third last one (212) with 195
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#!/usr/bin/python
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from math import *
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from sys import stdout
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# We want 0 at light=0 and 255 at light=LIGHT_MAX
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LIGHT_MAX = 14
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#FACTOR = 0.69
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#FACTOR = 0.75
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FACTOR = 0.83
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START_FROM_ZERO = False
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L = []
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if START_FROM_ZERO:
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for i in range(1,LIGHT_MAX+1):
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L.append(int(round(255.0 * FACTOR ** (i-1))))
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L.append(0)
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else:
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for i in range(1,LIGHT_MAX+1):
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L.append(int(round(255.0 * FACTOR ** (i-1))))
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L.append(255)
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L.reverse()
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for i in L:
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stdout.write(str(i)+",\n")
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*/
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u8 light_decode_table[LIGHT_MAX+1] =
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{
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23,
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27,
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33,
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40,
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48,
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57,
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69,
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83,
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100,
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121,
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146,
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176,
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195,
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220,
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255,
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};
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#endif
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#if 0
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// This is good
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// a_n+1 = a_n * 0.786
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// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
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// LIGHT_SUN is read as LIGHT_MAX from here.
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u8 light_decode_table[LIGHT_MAX+1] =
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{
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8,
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11,
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14,
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18,
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22,
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29,
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37,
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47,
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60,
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76,
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97,
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123,
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157,
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200,
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255,
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};
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#endif
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#if 0
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// Use for debugging in dark
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u8 light_decode_table[LIGHT_MAX+1] =
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{
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58,
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64,
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72,
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80,
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88,
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98,
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109,
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121,
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135,
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150,
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167,
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185,
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206,
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229,
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255,
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};
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#endif
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// This is reasonable with classic lighting with a light source
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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2,
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3,
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4,
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6,
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9,
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13,
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18,
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25,
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32,
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35,
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45,
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57,
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69,
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79,
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255
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};*/
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// As in minecraft, a_n+1 = a_n * 0.8
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// NOTE: This doesn't really work that well because this defines
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// LIGHT_MAX as dimmer than LIGHT_SUN
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// NOTE: Uh, this has had 34 left out; forget this.
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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8,
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11,
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14,
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17,
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21,
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27,
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42,
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53,
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66,
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83,
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104,
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130,
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163,
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204,
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255,
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};*/
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// This was a quick try of more light, manually quickly made
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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7,
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11,
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15,
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21,
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29,
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42,
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53,
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69,
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85,
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109,
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135,
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167,
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205,
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255,
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};*/
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// This was used for a long time, manually made
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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6,
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8,
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11,
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14,
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19,
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26,
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34,
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45,
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61,
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81,
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108,
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143,
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191,
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255,
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};*/
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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3,
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6,
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10,
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18,
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25,
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35,
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50,
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75,
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95,
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120,
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150,
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185,
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215,
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255,
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};*/
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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5,
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12,
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22,
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35,
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50,
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65,
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85,
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100,
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120,
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140,
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160,
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185,
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215,
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255,
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};*/
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// LIGHT_MAX is 14, 0-14 is 15 values
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/*u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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9,
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12,
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14,
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16,
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20,
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26,
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34,
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45,
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61,
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81,
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108,
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143,
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191,
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255,
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};*/
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#if 0
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/*
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#!/usr/bin/python
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from math import *
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from sys import stdout
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# We want 0 at light=0 and 255 at light=LIGHT_MAX
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LIGHT_MAX = 14
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#FACTOR = 0.69
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FACTOR = 0.75
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L = []
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for i in range(1,LIGHT_MAX+1):
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L.append(int(round(255.0 * FACTOR ** (i-1))))
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L.append(0)
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L.reverse()
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for i in L:
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stdout.write(str(i)+",\n")
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*/
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u8 light_decode_table[LIGHT_MAX+1] =
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{
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0,
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6,
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8,
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11,
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14,
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19,
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26,
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34,
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45,
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61,
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81,
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108,
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143,
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191,
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255,
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};
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#endif
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