Modified Files:

[simgear.git] / simgear / math / vector.cxx

diff --git a/simgear/math/vector.cxx b/simgear/math/vector.cxx
index 637ea4bc0803e8507e631828a6a69811bb34e66a..8a87fb5db4bd62d9da8e671ed290e23a342cd88a 100644 (file)
--- a/simgear/math/vector.cxx
+++ b/simgear/math/vector.cxx
@@ -2,7 +2,7 @@
 //
 // 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
@@ -14,10 +14,9 @@
 // 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.
 //
 // $Id$
 
@@ -30,10 +29,54 @@
 #include "vector.hxx"
 
 
+// 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.
+    // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
+    sgScaleVec3( u1, d, sgScalarProductVec3(u,d) / sgScalarProductVec3(d,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.
+    // u1 = ( dot_prod(u, d) / dot_prod(d, d) ) * d;
+    double ud = sgdScalarProductVec3(u, d);
+    double dd = sgdScalarProductVec3(d, d);
+    double tmp = ud / dd;
+
+    sgdScaleVec3(u1, d, tmp);;
+
+    // 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;
     
@@ -54,20 +97,19 @@ double sgPointLineDistSquared( const sgVec3 p, const sgVec3 p0,
 
 // 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;
+    double ud = sgdScalarProductVec3(u, d);
+    double dd = sgdScalarProductVec3(d, d);
+    double tmp = ud / dd;
 
     sgdScaleVec3(u1, d, tmp);;