imported Löve GLES branch (changeset 1ba9037e558b)

2026-08-16 00:02:31 +02:00 · 2013-12-05 18:05:13 +01:00
parent 41b2db04a7
commit 2644d1ee18
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+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#include "RandomGenerator.h"
+
+// STL
+#include <cmath>
+
+namespace love
+{
+namespace math
+{
+
+// 64 bit Xorshift implementation taken from the end of Sec. 3 (page 4) in
+// George Marsaglia, "Xorshift RNGs", Journal of Statistical Software, Vol.8 (Issue 14), 2003
+
+RandomGenerator::RandomGenerator()
+	: last_randomnormal(std::numeric_limits<double>::infinity())
+{
+	// because it is too big for some compilers to handle ... if you know what
+	// i mean
+#ifdef LOVE_BIG_ENDIAN
+	seed.b32.a = 0x0139408D;
+	seed.b32.b = 0xCBBF7A44;
+#else
+	seed.b32.b = 0x0139408D;
+	seed.b32.a = 0xCBBF7A44;
+#endif
+
+	rng_state = seed;
+}
+
+void RandomGenerator::setSeed(RandomGenerator::Seed newseed)
+{
+	// 0 xor 0 is still 0, so Xorshift can't generate new numbers.
+	if (newseed.b64 == 0)
+		throw love::Exception("Invalid random seed.");
+
+	seed = newseed;
+	rng_state = seed;
+}
+
+uint64 RandomGenerator::rand()
+{
+	rng_state.b64 ^= (rng_state.b64 << 13);
+	rng_state.b64 ^= (rng_state.b64 >> 7);
+	rng_state.b64 ^= (rng_state.b64 << 17);
+	return rng_state.b64;
+}
+
+// Box–Muller transform
+double RandomGenerator::randomNormal(double stddev)
+{
+	// use cached number if possible
+	if (last_randomnormal != std::numeric_limits<double>::infinity())
+	{
+		double r = last_randomnormal;
+		last_randomnormal = std::numeric_limits<double>::infinity();
+		return r * stddev;
+	}
+
+	double r   = sqrt(-2.0 * log(1. - random()));
+	double phi = 2.0 * LOVE_M_PI * (1. - random());
+
+	last_randomnormal = r * cos(phi);
+	return r * sin(phi) * stddev;
+}
+
+} // math
+} // love