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/*
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 long lsqr (long x)
{
return (long) 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) */
}
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