1 // vector.cxx -- additional vector routines
3 // Written by Curtis Olson, started December 1997.
5 // Copyright (C) 1997 Curtis L. Olson - http://www.flightgear.org/~curt
7 // This library is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU Library General Public
9 // License as published by the Free Software Foundation; either
10 // version 2 of the License, or (at your option) any later version.
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // Library 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 // #include <Include/fg_types.h>
32 // Given a point p, and a line through p0 with direction vector d,
33 // find the closest point (p1) on the line
34 void sgClosestPointToLine( sgVec3 p1, const sgVec3 p, const sgVec3 p0,
42 // calculate the projection, u1, of u along d.
43 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
44 sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,d) );
46 // calculate the point p1 along the line that is closest to p
48 sgAddVec3(p1, p0, u1);
52 // Given a point p, and a line through p0 with direction vector d,
53 // find the closest point (p1) on the line
54 void sgdClosestPointToLine( sgdVec3 p1, const sgdVec3 p, const sgdVec3 p0,
62 // calculate the projection, u1, of u along d.
63 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
64 double ud = sgdScalarProductVec3(u, d);
65 double dd = sgdScalarProductVec3(d, d);
68 sgdScaleVec3(u1, d, tmp);;
70 // calculate the point p1 along the line that is closest to p
72 sgdAddVec3(p1, p0, u1);
76 // Given a point p, and a line through p0 with direction vector d,
77 // find the shortest distance (squared) from the point to the line
78 double sgClosestPointToLineDistSquared( const sgVec3 p, const sgVec3 p0,
86 // calculate the projection, u1, of u along d.
87 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
88 sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,d) );
90 // v = u - u1 = vector from closest point on line, p1, to the
94 return ( sgScalarProductVec3(v, v) );
98 // Given a point p, and a line through p0 with direction vector d,
99 // find the shortest distance (squared) from the point to the line
100 double sgdClosestPointToLineDistSquared( const sgdVec3 p, const sgdVec3 p0,
106 sgdSubVec3(u, p, p0);
108 // calculate the projection, u1, of u along d.
109 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
110 double ud = sgdScalarProductVec3(u, d);
111 double dd = sgdScalarProductVec3(d, d);
112 double tmp = ud / dd;
114 sgdScaleVec3(u1, d, tmp);;
116 // v = u - u1 = vector from closest point on line, p1, to the
117 // original point, p.
118 sgdSubVec3(v, u, u1);
120 return ( sgdScalarProductVec3(v, v) );
124 // This is a quicker form of
125 // sgMakeMatTrans4( sgMat4 sgTrans, sgVec3 trans )
126 // sgPostMultMat4( sgMat, sgTRANS );
127 void sgPostMultMat4ByTransMat4( sgMat4 src, const sgVec3 trans )
129 for( int i=0; i<4; i++) {
130 for( int j=0; j<3; j++ ) {
131 src[i][j] += (src[i][3] * trans[j]);