From 31f0b79de3e23f3660c35795232020870fb38590 Mon Sep 17 00:00:00 2001
From: Jared Adams <jaxad0127@gmail.com>
Date: Tue, 14 Apr 2009 20:50:14 -0600
Subject: Add misisng mathutils files
---
src/utils/mathutils.cpp | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
src/utils/mathutils.h | 31 ++++++++++++++++++++++++++
2 files changed, 89 insertions(+)
create mode 100644 src/utils/mathutils.cpp
create mode 100644 src/utils/mathutils.h
diff --git a/src/utils/mathutils.cpp b/src/utils/mathutils.cpp
new file mode 100644
index 00000000..0ad8f3fb
--- /dev/null
+++ b/src/utils/mathutils.cpp
@@ -0,0 +1,58 @@
+/*
+ * The Mana World
+ * Copyright (C) 2009 The Mana World Development Team
+ *
+ * This file is part of The Mana World.
+ *
+ * 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
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "utils/mathutils.h"
+
+/* A very fast function to calculate the approximate inverse square root of a
+ * floating point value and a helper function that uses it for getting the
+ * normal squareroot. For an explanation of the inverse squareroot function
+ * read:
+ * http://www.math.purdue.edu/~clomont/Math/Papers/2003/InvSqrt.pdf
+ *
+ * Unfortunately the original creator of this function seems to be unknown.
+ */
+
+float fastInvSqrt(float x)
+{
+ union { int i; float x; } tmp;
+ float xhalf = 0.5f * x;
+ tmp.x = x;
+ tmp.i = 0x5f375a86 - (tmp.i >> 1);
+ x = tmp.x;
+ x = x * (1.5f - xhalf * x * x);
+ return x;
+}
+
+float fastSqrt(float x)
+{
+ return 1.0f / fastInvSqrt(x);
+}
+
+float weightedAverage(float n1, float n2, float w)
+{
+ if (w < 0.0f)
+ return n1;
+
+ if (w > 1.0f)
+ return n2;
+
+ return (w * n2 + (1.0f - w) * n1) / 2.0f;
+}
diff --git a/src/utils/mathutils.h b/src/utils/mathutils.h
new file mode 100644
index 00000000..1b68f223
--- /dev/null
+++ b/src/utils/mathutils.h
@@ -0,0 +1,31 @@
+/*
+ * The Mana World
+ * Copyright (C) 2009 The Mana World Development Team
+ *
+ * This file is part of The Mana World.
+ *
+ * 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
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef UTILS_MATHUTILS_H
+#define UTILS_MATHUTILS_H
+
+float fastInvSqrt(float x);
+
+float fastSqrt(float x);
+
+float weightedAverage(float n1, float n2, float w);
+
+#endif // UTILS_MATHUTILS_H
--
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