Initial. Don't... just don't ask.

threeDKit/quickmath.c

@@ -0,0 +1,118 @@
+/*
+
+    3DKIT   version   1.3
+    High speed 3D graphics and rendering library for Linux.
+
+    Copyright (C) 1996, 1997  Paul Sheer   psheer@icon.co.za
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    This library 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
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public
+    License along with this library; if not, write to the Free
+    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+    MA 02111-1307, USA
+
+*/
+
+
+#include <math.h>
+#include "quickmath.h"
+
+inline double fsqr (double x)
+{
+    return x * x;
+}
+
+inline int lsqr (int x)
+{
+    return (int) x * x;
+}
+
+inline double fmax (double a, double b)
+{
+    return max(a, b);
+}
+
+inline double fmin (double a, double b)
+{
+    return min(a, b);
+}
+
+inline double fsgn (double a)
+{
+	return (a == 0.0 ? 0.0 : (a > 0.0 ? 1.0 : -1.0));
+}
+
+inline double dot (Vec a, Vec b)
+{
+    return a.x * b.x + a.y * b.y + a.z * b.z;
+}
+
+Vec cross (Vec a, Vec b)
+{
+    Vec c;
+    c.x = a.y * b.z - a.z * b.y;
+    c.y = a.z * b.x - a.x * b.z;
+    c.z = a.x * b.y - a.y * b.x;
+    return c;
+}
+
+Vec plus (Vec a, Vec b)
+{
+    Vec c;
+    c.x = a.x + b.x;
+    c.y = a.y + b.y;
+    c.z = a.z + b.z;
+    return c;
+}
+
+Vec minus (Vec a, Vec b)
+{
+    Vec c;
+    c.x = a.x - b.x;
+    c.y = a.y - b.y;
+    c.z = a.z - b.z;
+    return c;
+}
+
+Vec times (Vec a, double f)
+{
+    Vec c;
+    c.x = a.x * f;
+    c.y = a.y * f;
+    c.z = a.z * f;
+    return c;
+}
+
+double norm (Vec a)
+{
+    return sqrt (sqr(a.x) + sqr(a.y) + sqr(a.z));
+}
+
+void orth_vectors(Vec X, Vec *r1, Vec *r2, double r)
+{
+    if (X.x == 0 && X.y == 0) {
+	r1->x = 1;
+	r1->y = 0;
+	r1->z = 0;
+    } else {
+	r1->x = X.y / sqrt (X.x * X.x + X.y * X.y);
+	r1->y = -X.x / sqrt (X.x * X.x + X.y * X.y);
+	r1->z = 0;
+    }
+    *r1 = times (*r1, r);		/* r1 now has length r */
+
+    *r2 = cross (X, *r1);
+    *r2 = times (*r2, r / norm (*r2));	/* r2 now has length r */
+
+/* r1 and r2 are now two vectors prependicular to each other and to (x,y,z) */
+}
+