1 // vector.cxx -- additional vector routines
3 // Written by Curtis Olson, started December 1997.
5 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 // (Log is kept at end of this file)
28 // #include <Include/fg_types.h>
35 #if !defined( USE_XTRA_MAT3_INLINES )
36 // Map a vector onto the plane specified by normal
37 void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
42 // calculate a vector "u1" representing the shortest distance from
43 // the plane specified by normal and v0 to a point specified by
44 // "vec". "u1" represents both the direction and magnitude of
45 // this desired distance.
47 // u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal
51 ( MAT3_DOT_PRODUCT(normal, vec) /
52 MAT3_DOT_PRODUCT(normal, normal)
56 // printf(" vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
57 // printf(" v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
58 // printf(" u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
60 // calculate the vector "v" which is the vector "vec" mapped onto
61 // the plane specified by "normal" and "v0".
65 MAT3_ADD_VEC(tmp, v0, vec);
66 MAT3_SUB_VEC(v, tmp, u1);
67 // printf(" v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]);
69 // Calculate the vector "result" which is "v" - "v0" which is a
70 // directional vector pointing from v0 towards v
74 MAT3_SUB_VEC(result, v, v0);
75 // printf(" result = %.2f, %.2f, %.2f\n",
76 // result[0], result[1], result[2]);
78 #endif // !defined( USE_XTRA_MAT3_INLINES )
81 // Given a point p, and a line through p0 with direction vector d,
82 // find the shortest distance from the point to the line
83 double fgPointLine(MAT3vec p, MAT3vec p0, MAT3vec d) {
85 double ud, dd, tmp, dist;
88 MAT3_SUB_VEC(u, p, p0);
90 // calculate the projection, u1, of u along d.
91 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
92 ud = MAT3_DOT_PRODUCT(u, d);
93 dd = MAT3_DOT_PRODUCT(d, d);
96 MAT3_SCALE_VEC(u1, d, tmp);;
98 // v = u - u1 = vector from closest point on line, p1, to the
100 MAT3_SUB_VEC(v, u, u1);
102 dist = sqrt(MAT3_DOT_PRODUCT(v, v));
108 // Given a point p, and a line through p0 with direction vector d,
109 // find the shortest distance (squared) from the point to the line
110 double fgPointLineSquared(MAT3vec p, MAT3vec p0, MAT3vec d) {
115 MAT3_SUB_VEC(u, p, p0);
117 // calculate the projection, u1, of u along d.
118 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
119 ud = MAT3_DOT_PRODUCT(u, d);
120 dd = MAT3_DOT_PRODUCT(d, d);
123 MAT3_SCALE_VEC(u1, d, tmp);;
125 // v = u - u1 = vector from closest point on line, p1, to the
126 // original point, p.
127 MAT3_SUB_VEC(v, u, u1);
129 return ( MAT3_DOT_PRODUCT(v, v) );
134 // Revision 1.5 1998/10/16 23:36:38 curt
137 // Revision 1.4 1998/10/16 00:50:31 curt
138 // Added point3d.hxx to replace cheezy fgPoint3d struct.
140 // Revision 1.3 1998/08/24 20:04:12 curt
141 // Various "inline" code optimizations contributed by Norman Vine.
143 // Revision 1.2 1998/07/24 21:34:38 curt
144 // fgPointLine() rewritten into fgPointLineSquared() ... this ultimately saves
145 // us from doing a sqrt().
147 // Revision 1.1 1998/07/08 14:40:10 curt
148 // polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
149 // Updated fg_geodesy comments to reflect that routines expect and produce
152 // Revision 1.3 1998/05/07 23:04:28 curt
153 // Added a blank formating line!
155 // Revision 1.2 1998/01/19 19:27:13 curt
156 // Merged in make system changes from Bob Kuehne <rpk@sgi.com>
157 // This should simplify things tremendously.
159 // Revision 1.1 1997/12/22 04:13:17 curt