3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published by
7 the Free Software Foundation; either version 2.1 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 #include "util/numeric.h"
27 static u8 light_LUT[LIGHT_SUN + 1];
29 // The const ref to light_LUT is what is actually used in the code
30 const u8 *light_decode_table = light_LUT;
32 // Initialize or update the light value tables using the specified gamma
33 void set_light_table(float gamma)
35 // Lighting curve derivatives
36 const float alpha = g_settings->getFloat("lighting_alpha");
37 const float beta = g_settings->getFloat("lighting_beta");
38 // Lighting curve coefficients
39 const float a = alpha + beta - 2.0f;
40 const float b = 3.0f - 2.0f * alpha - beta;
41 const float c = alpha;
43 const float d = g_settings->getFloat("lighting_boost");
44 const float e = g_settings->getFloat("lighting_boost_center");
45 const float f = g_settings->getFloat("lighting_boost_spread");
47 gamma = rangelim(gamma, 0.5f, 3.0f);
49 for (size_t i = 0; i < LIGHT_SUN; i++) {
52 float brightness = a * x * x * x + b * x * x + c * x;
53 float boost = d * std::exp(-((x - e) * (x - e)) / (2.0f * f * f));
54 brightness = powf(brightness + boost, 1.0f / gamma);
55 light_LUT[i] = rangelim((u32)(255.0f * brightness), 0, 255);
56 if (i > 1 && light_LUT[i] <= light_LUT[i - 1])
57 light_LUT[i] = light_LUT[i - 1] + 1;
59 light_LUT[LIGHT_SUN] = 255;