Initial commit

src/light.h

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+/*
+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 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.
+*/
+
+#pragma once
+#include <cassert>
+#include "irrlichttypes.h"
+
+/*
+	Lower level lighting stuff
+*/
+
+// This directly sets the range of light.
+// Actually this is not the real maximum, and this is not the brightest, the
+// brightest is LIGHT_SUN.
+// If changed, this constant as defined in builtin/game/constants.lua must
+// also be changed.
+#define LIGHT_MAX 14
+// Light is stored as 4 bits, thus 15 is the maximum.
+// This brightness is reserved for sunlight
+#define LIGHT_SUN 15
+
+#ifndef SERVER
+
+/**
+ * \internal
+ *
+ * \warning DO NOT USE this directly; it is here simply so that decode_light()
+ * can be inlined.
+ *
+ * Array size is #LIGHTMAX+1
+ *
+ * The array is a lookup table to convert the internal representation of light
+ * (brightness) to the display brightness.
+ *
+ */
+extern const u8 *light_decode_table;
+
+// 0 <= light <= LIGHT_SUN
+// 0 <= return value <= 255
+inline u8 decode_light(u8 light)
+{
+	// assert(light <= LIGHT_SUN);
+	if (light > LIGHT_SUN)
+		light = LIGHT_SUN;
+	return light_decode_table[light];
+}
+
+// 0.0 <= light <= 1.0
+// 0.0 <= return value <= 1.0
+float decode_light_f(float light_f);
+
+void set_light_table(float gamma);
+
+#endif // ifndef SERVER
+
+// 0 <= daylight_factor <= 1000
+// 0 <= lightday, lightnight <= LIGHT_SUN
+// 0 <= return value <= LIGHT_SUN
+inline u8 blend_light(u32 daylight_factor, u8 lightday, u8 lightnight)
+{
+	u32 c = 1000;
+	u32 l = ((daylight_factor * lightday + (c - daylight_factor) * lightnight)) / c;
+	if (l > LIGHT_SUN)
+		l = LIGHT_SUN;
+	return l;
+}