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greg |
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/* Copyright (c) 1994 Regents of the University of California */
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#ifndef lint
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static char SCCSid[] = "$SunId$ LBL";
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#endif
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/*
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* Routines for 3-d vectors
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*/
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#include <stdio.h>
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#include <math.h>
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#include "parser.h"
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double
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normalize(v) /* normalize a vector, return old magnitude */
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register FVECT v;
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{
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static double len;
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len = v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
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if (len <= 0.0)
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return(0.0);
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len = sqrt(len);
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v[0] /= len;
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v[1] /= len;
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v[2] /= len;
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return(len);
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}
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fcross(vres, v1, v2) /* vres = v1 X v2 */
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register FVECT vres, v1, v2;
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{
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vres[0] = v1[1]*v2[2] - v1[2]*v2[1];
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vres[1] = v1[2]*v2[0] - v1[0]*v2[2];
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vres[2] = v1[0]*v2[1] - v1[1]*v2[0];
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}
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