1 /**************************************************************************
2 * vector.c -- additional vector routines
4 * Written by Curtis Olson, started December 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
30 #include <Include/fg_types.h>
37 /* Map a vector onto the plane specified by normal */
38 void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
43 /* calculate a vector "u1" representing the shortest distance from
44 * the plane specified by normal and v0 to a point specified by
45 * "vec". "u1" represents both the direction and magnitude of
46 * this desired distance. */
48 /* u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal */
52 ( MAT3_DOT_PRODUCT(normal, vec) /
53 MAT3_DOT_PRODUCT(normal, normal)
58 printf(" vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
59 printf(" v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
60 printf(" u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
63 /* calculate the vector "v" which is the vector "vec" mapped onto
64 the plane specified by "normal" and "v0". */
66 /* v = v0 + vec - u1 */
68 MAT3_ADD_VEC(tmp, v0, vec);
69 MAT3_SUB_VEC(v, tmp, u1);
70 /* printf(" v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]); */
72 /* Calculate the vector "result" which is "v" - "v0" which is a
73 * directional vector pointing from v0 towards v */
77 MAT3_SUB_VEC(result, v, v0);
78 /* printf(" result = %.2f, %.2f, %.2f\n",
79 result[0], result[1], result[2]); */
83 // Given a point p, and a line through p0 with direction vector d,
84 // find the shortest distance (squared) from the point to the line
85 double fgPointLineSquared(MAT3vec p, MAT3vec p0, MAT3vec d) {
90 MAT3_SUB_VEC(u, p, p0);
92 // calculate the projection, u1, of u along d.
93 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
94 ud = MAT3_DOT_PRODUCT(u, d);
95 dd = MAT3_DOT_PRODUCT(d, d);
98 MAT3_SCALE_VEC(u1, d, tmp);;
100 // v = u - u1 = vector from closest point on line, p1, to the
101 // original point, p.
102 MAT3_SUB_VEC(v, u, u1);
104 return ( MAT3_DOT_PRODUCT(v, v) );
109 /* Revision 1.2 1998/07/24 21:34:38 curt
110 /* fgPointLine() rewritten into fgPointLineSquared() ... this ultimately saves
111 /* us from doing a sqrt().
113 * Revision 1.1 1998/07/08 14:40:10 curt
114 * polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
115 * Updated fg_geodesy comments to reflect that routines expect and produce
118 * Revision 1.3 1998/05/07 23:04:28 curt
119 * Added a blank formating line!
121 * Revision 1.2 1998/01/19 19:27:13 curt
122 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
123 * This should simplify things tremendously.
125 * Revision 1.1 1997/12/22 04:13:17 curt