133 lines
3.8 KiB
C++
133 lines
3.8 KiB
C++
/**************************************************************************
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* vector.c -- additional vector routines
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*
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* Written by Curtis Olson, started December 1997.
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*
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* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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* (Log is kept at end of this file)
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**************************************************************************/
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#include <math.h>
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#include <stdio.h>
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#include <Include/fg_types.h>
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#include "vector.hxx"
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#include "mat3.h"
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/* Map a vector onto the plane specified by normal */
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void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
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MAT3vec result)
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{
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MAT3vec u1, v, tmp;
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/* calculate a vector "u1" representing the shortest distance from
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* the plane specified by normal and v0 to a point specified by
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* "vec". "u1" represents both the direction and magnitude of
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* this desired distance. */
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/* u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal */
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MAT3_SCALE_VEC( u1,
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normal,
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( MAT3_DOT_PRODUCT(normal, vec) /
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MAT3_DOT_PRODUCT(normal, normal)
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)
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);
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/*
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printf(" vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
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printf(" v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
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printf(" u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
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*/
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/* calculate the vector "v" which is the vector "vec" mapped onto
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the plane specified by "normal" and "v0". */
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/* v = v0 + vec - u1 */
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MAT3_ADD_VEC(tmp, v0, vec);
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MAT3_SUB_VEC(v, tmp, u1);
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/* printf(" v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]); */
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/* Calculate the vector "result" which is "v" - "v0" which is a
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* directional vector pointing from v0 towards v */
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/* result = v - v0 */
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MAT3_SUB_VEC(result, v, v0);
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/* printf(" result = %.2f, %.2f, %.2f\n",
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result[0], result[1], result[2]); */
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}
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// Given a point p, and a line through p0 with direction vector d,
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// find the shortest distance (squared) from the point to the line
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double fgPointLineSquared(MAT3vec p, MAT3vec p0, MAT3vec d) {
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MAT3vec u, u1, v;
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double ud, dd, tmp;
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// u = p - p0
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MAT3_SUB_VEC(u, p, p0);
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// calculate the projection, u1, of u along d.
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// u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
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ud = MAT3_DOT_PRODUCT(u, d);
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dd = MAT3_DOT_PRODUCT(d, d);
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tmp = ud / dd;
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MAT3_SCALE_VEC(u1, d, tmp);;
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// v = u - u1 = vector from closest point on line, p1, to the
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// original point, p.
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MAT3_SUB_VEC(v, u, u1);
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return ( MAT3_DOT_PRODUCT(v, v) );
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}
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/* $Log$
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/* Revision 1.2 1998/07/24 21:34:38 curt
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/* fgPointLine() rewritten into fgPointLineSquared() ... this ultimately saves
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/* us from doing a sqrt().
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/*
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* Revision 1.1 1998/07/08 14:40:10 curt
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* polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
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* Updated fg_geodesy comments to reflect that routines expect and produce
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* meters.
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*
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* Revision 1.3 1998/05/07 23:04:28 curt
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* Added a blank formating line!
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*
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* Revision 1.2 1998/01/19 19:27:13 curt
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* Merged in make system changes from Bob Kuehne <rpk@sgi.com>
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* This should simplify things tremendously.
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*
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* Revision 1.1 1997/12/22 04:13:17 curt
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* Initial revision.
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* */
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