Initial commit

src/daynightratio.h

@@ -0,0 +1,72 @@
+/*
+Minetest
+Copyright (C) 2010-2013 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
+
+inline u32 time_to_daynight_ratio(float time_of_day, bool smooth)
+{
+	float t = time_of_day;
+	if (t < 0.0f)
+		t += ((int)(-t) / 24000) * 24000.0f;
+	if (t >= 24000.0f)
+		t -= ((int)(t) / 24000) * 24000.0f;
+	if (t > 12000.0f)
+		t = 24000.0f - t;
+
+	const float values[9][2] = {
+		{4250.0f + 125.0f, 175.0f},
+		{4500.0f + 125.0f, 175.0f},
+		{4750.0f + 125.0f, 250.0f},
+		{5000.0f + 125.0f, 350.0f},
+		{5250.0f + 125.0f, 500.0f},
+		{5500.0f + 125.0f, 675.0f},
+		{5750.0f + 125.0f, 875.0f},
+		{6000.0f + 125.0f, 1000.0f},
+		{6250.0f + 125.0f, 1000.0f},
+	};
+
+	if (!smooth) {
+		float lastt = values[0][0];
+		for (u32 i = 1; i < 9; i++) {
+			float t0 = values[i][0];
+			float switch_t = (t0 + lastt) / 2.0f;
+			lastt = t0;
+			if (switch_t <= t)
+				continue;
+
+			return values[i][1];
+		}
+		return 1000;
+	}
+
+	if (t <= 4625.0f) // 4500 + 125
+		return values[0][1];
+	else if (t >= 6125.0f) // 6000 + 125
+		return 1000;
+
+	for (u32 i = 0; i < 9; i++) {
+		if (values[i][0] <= t)
+			continue;
+
+		float td0 = values[i][0] - values[i - 1][0];
+		float f = (t - values[i - 1][0]) / td0;
+		return f * values[i][1] + (1.0f - f) * values[i - 1][1];
+	}
+	return 1000;
+}