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>
32 // Given a point p, and a line through p0 with direction vector d,
33 // find the shortest distance (squared) from the point to the line
34 double sgPointLineDistSquared( 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 // v = u - u1 = vector from closest point on line, p1, to the
50 return ( sgScalarProductVec3(v, v) );
54 // Given a point p, and a line through p0 with direction vector d,
55 // find the shortest distance (squared) from the point to the line
56 double sgdPointLineDistSquared( const sgdVec3 p, const sgdVec3 p0,
65 // calculate the projection, u1, of u along d.
66 // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
67 ud = sgdScalarProductVec3(u, d);
68 dd = sgdScalarProductVec3(d, d);
71 sgdScaleVec3(u1, d, tmp);;
73 // v = u - u1 = vector from closest point on line, p1, to the
77 return ( sgdScalarProductVec3(v, v) );
81 // This is a quicker form of
82 // sgMakeMatTrans4( sgMat4 sgTrans, sgVec3 trans )
83 // sgPostMultMat4( sgMat, sgTRANS );
84 void sgPostMultMat4ByTransMat4( sgMat4 src, const sgVec3 trans )
86 for( int i=0; i<4; i++) {
87 for( int j=0; j<3; j++ ) {
88 src[i][j] += (src[i][3] * trans[j]);