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 Library General Public
18 // License along with this library; if not, write to the
19 // Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 // Boston, MA 02111-1307, USA.
28 // #include <Include/fg_types.h>
33 // Given a point p, and a line through p0 with direction vector d,
34 // find the closest point (p1) on the line
35 void sgClosestPointToLine( sgVec3 p1, const sgVec3 p, const sgVec3 p0,
43 // calculate the projection, u1, of u along d.
44 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
45 sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,d) );
47 // calculate the point p1 along the line that is closest to p
49 sgAddVec3(p1, p0, u1);
53 // Given a point p, and a line through p0 with direction vector d,
54 // find the closest point (p1) on the line
55 void sgdClosestPointToLine( sgdVec3 p1, const sgdVec3 p, const sgdVec3 p0,
63 // calculate the projection, u1, of u along d.
64 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
65 double ud = sgdScalarProductVec3(u, d);
66 double dd = sgdScalarProductVec3(d, d);
69 sgdScaleVec3(u1, d, tmp);;
71 // calculate the point p1 along the line that is closest to p
73 sgdAddVec3(p1, p0, u1);
77 // Given a point p, and a line through p0 with direction vector d,
78 // find the shortest distance (squared) from the point to the line
79 double sgClosestPointToLineDistSquared( const sgVec3 p, const sgVec3 p0,
87 // calculate the projection, u1, of u along d.
88 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
89 sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,d) );
91 // v = u - u1 = vector from closest point on line, p1, to the
95 return ( sgScalarProductVec3(v, v) );
99 // Given a point p, and a line through p0 with direction vector d,
100 // find the shortest distance (squared) from the point to the line
101 double sgdClosestPointToLineDistSquared( const sgdVec3 p, const sgdVec3 p0,
107 sgdSubVec3(u, p, p0);
109 // calculate the projection, u1, of u along d.
110 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
111 double ud = sgdScalarProductVec3(u, d);
112 double dd = sgdScalarProductVec3(d, d);
113 double tmp = ud / dd;
115 sgdScaleVec3(u1, d, tmp);;
117 // v = u - u1 = vector from closest point on line, p1, to the
118 // original point, p.
119 sgdSubVec3(v, u, u1);
121 return ( sgdScalarProductVec3(v, v) );
125 // This is a quicker form of
126 // sgMakeMatTrans4( sgMat4 sgTrans, sgVec3 trans )
127 // sgPostMultMat4( sgMat, sgTRANS );
128 void sgPostMultMat4ByTransMat4( sgMat4 src, const sgVec3 trans )
130 for( int i=0; i<4; i++) {
131 for( int j=0; j<3; j++ ) {
132 src[i][j] += (src[i][3] * trans[j]);