+/**************************************************************************
+ * vector.c -- additional vector routines
+ *
+ * Written by Curtis Olson, started December 1997.
+ *
+ * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id$
+ * (Log is kept at end of this file)
+ **************************************************************************/
+
+
+#include <math.h>
+#include <stdio.h>
+
+#include <Include/fg_types.h>
+
+#include "vector.hxx"
+
+#include "mat3.h"
+
+
+/* Map a vector onto the plane specified by normal */
+void map_vec_onto_cur_surface_plane(MAT3vec normal, MAT3vec v0, MAT3vec vec,
+ MAT3vec result)
+{
+ MAT3vec u1, v, tmp;
+
+ /* calculate a vector "u1" representing the shortest distance from
+ * the plane specified by normal and v0 to a point specified by
+ * "vec". "u1" represents both the direction and magnitude of
+ * this desired distance. */
+
+ /* u1 = ( (normal <dot> vec) / (normal <dot> normal) ) * normal */
+
+ MAT3_SCALE_VEC( u1,
+ normal,
+ ( MAT3_DOT_PRODUCT(normal, vec) /
+ MAT3_DOT_PRODUCT(normal, normal)
+ )
+ );
+
+ /*
+ printf(" vec = %.2f, %.2f, %.2f\n", vec[0], vec[1], vec[2]);
+ printf(" v0 = %.2f, %.2f, %.2f\n", v0[0], v0[1], v0[2]);
+ printf(" u1 = %.2f, %.2f, %.2f\n", u1[0], u1[1], u1[2]);
+ */
+
+ /* calculate the vector "v" which is the vector "vec" mapped onto
+ the plane specified by "normal" and "v0". */
+
+ /* v = v0 + vec - u1 */
+
+ MAT3_ADD_VEC(tmp, v0, vec);
+ MAT3_SUB_VEC(v, tmp, u1);
+ /* printf(" v = %.2f, %.2f, %.2f\n", v[0], v[1], v[2]); */
+
+ /* Calculate the vector "result" which is "v" - "v0" which is a
+ * directional vector pointing from v0 towards v */
+
+ /* result = v - v0 */
+
+ MAT3_SUB_VEC(result, v, v0);
+ /* printf(" result = %.2f, %.2f, %.2f\n",
+ result[0], result[1], result[2]); */
+}
+
+
+// Given a point p, and a line through p0 with direction vector d,
+// find the shortest distance from the point to the line
+double fgPointLine(MAT3vec p, MAT3vec p0, MAT3vec d) {
+ MAT3vec u, u1, v;
+ double ud, dd, tmp, dist;
+
+ // u = p - p0
+ MAT3_SUB_VEC(u, p, p0);
+
+ // calculate the projection, u1, of u along d.
+ // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
+ ud = MAT3_DOT_PRODUCT(u, d);
+ dd = MAT3_DOT_PRODUCT(d, d);
+ tmp = ud / dd;
+
+ MAT3_SCALE_VEC(u1, d, tmp);;
+
+ // v = u - u1 = vector from closest point on line, p1, to the
+ // original point, p.
+ MAT3_SUB_VEC(v, u, u1);
+
+ dist = sqrt(MAT3_DOT_PRODUCT(v, v));
+
+ return( dist );
+}
+
+
+/* $Log$
+/* Revision 1.1 1998/07/08 14:40:10 curt
+/* polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
+/* Updated fg_geodesy comments to reflect that routines expect and produce
+/* meters.
+/*
+ * Revision 1.3 1998/05/07 23:04:28 curt
+ * Added a blank formating line!
+ *
+ * Revision 1.2 1998/01/19 19:27:13 curt
+ * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
+ * This should simplify things tremendously.
+ *
+ * Revision 1.1 1997/12/22 04:13:17 curt
+ * Initial revision.
+ * */
+
+
+
+
+