/*
-Minetest-c55
-Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+Minetest
+Copyright (C) 2013 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
+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 General Public License for more details.
+GNU Lesser General Public License for more details.
-You should have received a copy of the GNU General Public License along
+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"
+#include <cmath>
+#include "util/numeric.h"
+#include "settings.h"
-#if 1
-// 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,
-};
-#else
-// 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
+#ifndef SERVER
-from math import *
-from sys import stdout
+static u8 light_LUT[LIGHT_SUN + 1];
-# We want 0 at light=0 and 255 at light=LIGHT_MAX
-LIGHT_MAX = 14
-#FACTOR = 0.69
-FACTOR = 0.75
+// The const ref to light_LUT is what is actually used in the code
+const u8 *light_decode_table = light_LUT;
-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,
+struct LightingParams {
+ float a, b, c; // Lighting curve polynomial coefficients
+ float boost, center, sigma; // Lighting curve parametric boost
+ float gamma; // Lighting curve gamma correction
};
-#endif
+static LightingParams params;
+
+float decode_light_f(float x)
+{
+ if (x >= 1.0f) // x is often 1.0f
+ return 1.0f;
+ x = std::fmax(x, 0.0f);
+ float brightness = ((params.a * x + params.b) * x + params.c) * x;
+ brightness += params.boost *
+ std::exp(-0.5f * sqr((x - params.center) / params.sigma));
+ if (brightness <= 0.0f) // May happen if parameters are extreme
+ return 0.0f;
+ if (brightness >= 1.0f)
+ return 1.0f;
+ return powf(brightness, 1.0f / params.gamma);
+}
+
+
+// Initialize or update the light value tables using the specified gamma
+void set_light_table(float gamma)
+{
+// Lighting curve bounding gradients
+ const float alpha = rangelim(g_settings->getFloat("lighting_alpha"), 0.0f, 3.0f);
+ const float beta = rangelim(g_settings->getFloat("lighting_beta"), 0.0f, 3.0f);
+// Lighting curve polynomial coefficients
+ params.a = alpha + beta - 2.0f;
+ params.b = 3.0f - 2.0f * alpha - beta;
+ params.c = alpha;
+// Lighting curve parametric boost
+ params.boost = rangelim(g_settings->getFloat("lighting_boost"), 0.0f, 0.4f);
+ params.center = rangelim(g_settings->getFloat("lighting_boost_center"), 0.0f, 1.0f);
+ params.sigma = rangelim(g_settings->getFloat("lighting_boost_spread"), 0.0f, 0.4f);
+// Lighting curve gamma correction
+ params.gamma = rangelim(gamma, 0.33f, 3.0f);
+
+// Boundary values should be fixed
+ light_LUT[0] = 0;
+ light_LUT[LIGHT_SUN] = 255;
+
+ for (size_t i = 1; i < LIGHT_SUN; i++) {
+ float brightness = decode_light_f((float)i / LIGHT_SUN);
+ // Strictly speaking, rangelim is not necessary here—if the implementation
+ // is conforming. But we don’t want problems in any case.
+ light_LUT[i] = rangelim((s32)(255.0f * brightness), 0, 255);
+ // Ensure light brightens with each level
+ if (i > 1 && light_LUT[i] <= light_LUT[i - 1])
+ light_LUT[i] = light_LUT[i - 1] + 1;
+ }
+}
+
+#endif
projects / oweals / minetest.git / blobdiff