/*
-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"
-
-/*
-
-#!/usr/bin/python
-
-from math import *
-from sys import stdout
-
-# We want 0 at light=0 and 255 at light=LIGHT_MAX
-LIGHT_MAX = 15
-
-L = []
-for i in range(1,LIGHT_MAX+1):
- L.append(int(round(255.0 * 0.69 ** (i-1))))
- L.append(0)
-
-L.reverse()
-for i in L:
- stdout.write(str(i)+",\n")
-
-*/
-
-/*
- The first value should be 0, the last value should be 255.
-*/
-/*u8 light_decode_table[LIGHT_MAX+1] =
-{
-0,
-2,
-3,
-4,
-6,
-9,
-13,
-19,
-28,
-40,
-58,
-84,
-121,
-176,
-255,
-};*/
-
-/*
-#!/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] =
+#include <math.h>
+#include "util/numeric.h"
+
+#ifndef SERVER
+
+// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
+// LIGHT_SUN is read as LIGHT_MAX from here.
+
+u8 light_LUT[LIGHT_MAX+1];
+
+// the const ref to light_LUT is what is actually used in the code.
+const u8 *light_decode_table = light_LUT;
+
+/** Initialize or update the light value tables using the specified \p gamma.
+ * If \p gamma == 1.0 then the light table is linear. Typically values for
+ * gamma range between 1.8 and 2.2.
+ *
+ * @note The value for gamma will be restricted to the range 1.1 <= gamma <= 3.0.
+ *
+ * @note This function is not, currently, a simple linear to gamma encoding
+ * because adjustments are made so that a gamma of 1.8 gives the same
+ * results as those hardcoded for use by the server.
+ */
+void set_light_table(float gamma)
{
-0,
-6,
-8,
-11,
-14,
-19,
-26,
-34,
-45,
-61,
-81,
-108,
-143,
-191,
-255,
-};
-
-/*
-#!/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
-
-maxlight = 255
-minlight = 8
-
-L = []
-for i in range(1,LIGHT_MAX+1):
- L.append(minlight+int(round((maxlight-minlight) * FACTOR ** (i-1))))
- #L.append(int(round(255.0 * FACTOR ** (i-1))))
-L.append(minlight)
-
-L.reverse()
-for i in L:
- stdout.write(str(i)+",\n")
-*/
-/*u8 light_decode_table[LIGHT_MAX+1] =
-{
-8,
-14,
-16,
-18,
-22,
-27,
-33,
-41,
-52,
-67,
-86,
-112,
-147,
-193,
-255,
-};*/
-
+ static const float brightness_step = 255.0f / (LIGHT_MAX + 1);
+
+ // this table is pure arbitrary values, made so that
+ // at gamma 2.2 the game looks not too dark at light=1,
+ // and mostly linear for the rest of the scale.
+ // we could try to inverse the gamma power function, but this
+ // is simpler and quicker.
+ static const int adjustments[LIGHT_MAX + 1] = {
+ -67,
+ -91,
+ -125,
+ -115,
+ -104,
+ -85,
+ -70,
+ -63,
+ -56,
+ -49,
+ -42,
+ -35,
+ -28,
+ -22,
+ 0
+ };
+
+ gamma = rangelim(gamma, 1.0, 3.0);
+
+ float brightness = brightness_step;
+
+ for (size_t i = 0; i < LIGHT_MAX; i++) {
+ light_LUT[i] = (u8)(255 * powf(brightness / 255.0f, 1.0 / gamma));
+ light_LUT[i] = rangelim(light_LUT[i] + adjustments[i], 0, 255);
+ if (i > 1 && light_LUT[i] < light_LUT[i - 1])
+ light_LUT[i] = light_LUT[i - 1] + 1;
+ brightness += brightness_step;
+ }
+ light_LUT[LIGHT_MAX] = 255;
+}
+#endif
projects / oweals / minetest.git / blobdiff