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.
27 // #include <Include/fg_types.h>
34 #if !defined( USE_XTRA_MAT3_INLINES )
35 // Map a vector onto the plane specified by normal
36 void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
41 // calculate a vector "u1" representing the shortest distance from
42 // the plane specified by normal and v0 to a point specified by
43 // "vec". "u1" represents both the direction and magnitude of
44 // this desired distance.
46 // u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal
50 ( MAT3_DOT_PRODUCT(normal, vec) /
51 MAT3_DOT_PRODUCT(normal, normal)
55 // printf(" vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
56 // printf(" v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
57 // printf(" u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
59 // calculate the vector "v" which is the vector "vec" mapped onto
60 // the plane specified by "normal" and "v0".
64 MAT3_ADD_VEC(tmp, v0, vec);
65 MAT3_SUB_VEC(v, tmp, u1);
66 // printf(" v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]);
68 // Calculate the vector "result" which is "v" - "v0" which is a
69 // directional vector pointing from v0 towards v
73 MAT3_SUB_VEC(result, v, v0);
74 // printf(" result = %.2f, %.2f, %.2f\n",
75 // result[0], result[1], result[2]);
77 #endif // !defined( USE_XTRA_MAT3_INLINES )
80 // Given a point p, and a line through p0 with direction vector d,
81 // find the shortest distance from the point to the line
82 double fgPointLine(MAT3vec p, MAT3vec p0, MAT3vec d) {
87 MAT3_SUB_VEC(u, p, p0);
89 // calculate the projection, u1, of u along d.
90 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
91 ud = MAT3_DOT_PRODUCT(u, d);
92 dd = MAT3_DOT_PRODUCT(d, d);
95 MAT3_SCALE_VEC(u1, d, tmp);;
97 // v = u - u1 = vector from closest point on line, p1, to the
99 MAT3_SUB_VEC(v, u, u1);
101 return sqrt(MAT3_DOT_PRODUCT(v, v));
105 // Given a point p, and a line through p0 with direction vector d,
106 // find the shortest distance (squared) from the point to the line
107 double fgPointLineSquared(MAT3vec p, MAT3vec p0, MAT3vec d) {
112 MAT3_SUB_VEC(u, p, p0);
114 // calculate the projection, u1, of u along d.
115 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
116 ud = MAT3_DOT_PRODUCT(u, d);
117 dd = MAT3_DOT_PRODUCT(d, d);
120 MAT3_SCALE_VEC(u1, d, tmp);;
122 // v = u - u1 = vector from closest point on line, p1, to the
123 // original point, p.
124 MAT3_SUB_VEC(v, u, u1);
126 return ( MAT3_DOT_PRODUCT(v, v) );