//
// Written by Curtis Olson, started December 1997.
//
-// Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
+// Copyright (C) 1997 Curtis L. Olson - http://www.flightgear.org/~curt
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Library General Public License for more details.
//
-// You should have received a copy of the GNU Library General Public
-// License along with this library; if not, write to the
-// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-// Boston, MA 02111-1307, USA.
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#include "vector.hxx"
+// calculate the projection, p, of u along the direction of d.
+void sgProjection(sgVec3 p, const sgVec3 u, const sgVec3 d){
+ double denom = sgScalarProductVec3(d,d);
+ if (denom == 0.) sgCopyVec3(p, u);
+ else sgScaleVec3(p, d, sgScalarProductVec3(u,d) / denom);
+}
+
+// Same thing, except using double precision
+void sgProjection(sgdVec3 p, const sgdVec3 u, const sgdVec3 d){
+ double denom = sgdScalarProductVec3(d,d);
+ if (denom == 0.) sgdCopyVec3(p, u);
+ else sgdScaleVec3(p, d, sgdScalarProductVec3(u,d) / denom);
+}
+
+// Given a point p, and a line through p0 with direction vector d,
+// find the closest point (p1) on the line
+void sgClosestPointToLine( sgVec3 p1, const sgVec3 p, const sgVec3 p0,
+ const sgVec3 d ) {
+
+ sgVec3 u, u1;
+
+ // u = p - p0
+ sgSubVec3(u, p, p0);
+
+ // calculate the projection, u1, of u along d.
+ sgProjection(u1, u, d);
+
+ // calculate the point p1 along the line that is closest to p
+ // p0 = p1 + u1
+ sgAddVec3(p1, p0, u1);
+}
+
+
+// Given a point p, and a line through p0 with direction vector d,
+// find the closest point (p1) on the line
+void sgdClosestPointToLine( sgdVec3 p1, const sgdVec3 p, const sgdVec3 p0,
+ const sgdVec3 d ) {
+
+ sgdVec3 u, u1;
+
+ // u = p - p0
+ sgdSubVec3(u, p, p0);
+
+ // calculate the projection, u1, of u along d.
+ sgProjection(u1, u, d);
+
+ // calculate the point p1 along the line that is closest to p
+ // p0 = p1 + u1
+ sgdAddVec3(p1, p0, u1);
+}
+
+
// Given a point p, and a line through p0 with direction vector d,
// find the shortest distance (squared) from the point to the line
-double sgPointLineDistSquared( const sgVec3 p, const sgVec3 p0,
- const sgVec3 d ) {
+double sgClosestPointToLineDistSquared( const sgVec3 p, const sgVec3 p0,
+ const sgVec3 d ) {
sgVec3 u, u1, v;
sgSubVec3(u, p, p0);
// calculate the projection, u1, of u along d.
- // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
- sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,d) );
+ sgProjection(u1, u, d);
// v = u - u1 = vector from closest point on line, p1, to the
// original point, p.
// Given a point p, and a line through p0 with direction vector d,
// find the shortest distance (squared) from the point to the line
-double sgdPointLineDistSquared( const sgdVec3 p, const sgdVec3 p0,
- const sgdVec3 d ) {
+double sgdClosestPointToLineDistSquared( const sgdVec3 p, const sgdVec3 p0,
+ const sgdVec3 d ) {
sgdVec3 u, u1, v;
- double ud, dd, tmp;
// u = p - p0
sgdSubVec3(u, p, p0);
// calculate the projection, u1, of u along d.
- // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
- ud = sgdScalarProductVec3(u, d);
- dd = sgdScalarProductVec3(d, d);
- tmp = ud / dd;
-
- sgdScaleVec3(u1, d, tmp);;
+ sgProjection(u1, u, d);
// v = u - u1 = vector from closest point on line, p1, to the
// original point, p.