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/* Copyright (c) 1998 Silicon Graphics, Inc. */
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#ifndef lint
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static char SCCSid[] = "$SunId$ SGI";
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#endif
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/*
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* fvect.c - routines for float vector calculations
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*
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* 8/14/85
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*/
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#include <math.h>
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#include "fvect.h"
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double
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fdot(v1, v2) /* return the dot product of two vectors */
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register FVECT v1, v2;
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{
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return(DOT(v1,v2));
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}
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double
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dist2(p1, p2) /* return square of distance between points */
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register FVECT p1, p2;
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{
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FVECT delta;
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delta[0] = p2[0] - p1[0];
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delta[1] = p2[1] - p1[1];
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delta[2] = p2[2] - p1[2];
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return(DOT(delta, delta));
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}
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double
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dist2line(p, ep1, ep2) /* return square of distance to line */
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FVECT p; /* the point */
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FVECT ep1, ep2; /* points on the line */
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{
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register double d, d1, d2;
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d = dist2(ep1, ep2);
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d1 = dist2(ep1, p);
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d2 = d + d1 - dist2(ep2, p);
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return(d1 - 0.25*d2*d2/d);
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}
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double
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dist2lseg(p, ep1, ep2) /* return square of distance to line segment */
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FVECT p; /* the point */
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FVECT ep1, ep2; /* the end points */
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{
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register double d, d1, d2;
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d = dist2(ep1, ep2);
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d1 = dist2(ep1, p);
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d2 = dist2(ep2, p);
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if (d2 > d1) { /* check if past endpoints */
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if (d2 - d1 > d)
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return(d1);
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} else {
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if (d1 - d2 > d)
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return(d2);
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}
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d2 = d + d1 - d2;
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return(d1 - 0.25*d2*d2/d); /* distance to line */
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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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fvsum(vres, v0, v1, f) /* vres = v0 + f*v1 */
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register FVECT vres, v0, v1;
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register double f;
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{
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vres[0] = v0[0] + f*v1[0];
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vres[1] = v0[1] + f*v1[1];
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vres[2] = v0[2] + f*v1[2];
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}
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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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register double len, d;
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d = DOT(v, v);
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if (d <= 0.0)
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return(0.0);
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if (d <= 1.0+FTINY && d >= 1.0-FTINY)
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len = 0.5 + 0.5*d; /* first order approximation */
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else
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len = sqrt(d);
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v[0] *= d = 1.0/len;
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v[1] *= d;
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v[2] *= d;
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return(len);
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}
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spinvector(vres, vorig, vnorm, theta) /* rotate vector around normal */
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FVECT vres, vorig, vnorm;
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double theta;
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{
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double sint, cost, normprod;
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FVECT vperp;
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register int i;
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if (theta == 0.0) {
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if (vres != vorig)
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VCOPY(vres, vorig);
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return;
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}
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cost = cos(theta);
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sint = sin(theta);
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normprod = DOT(vorig, vnorm)*(1.-cost);
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fcross(vperp, vnorm, vorig);
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for (i = 0; i < 3; i++)
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vres[i] = vorig[i]*cost + vnorm[i]*normprod + vperp[i]*sint;
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}
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