X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fmath%2Fvector.cxx;h=a5d3ee0a6c2337efb583c2a53b5f6ac4a649d94e;hb=f19e83dcf10d5fced3d799c884a4654d7ada6548;hp=c67ff8ff13ab4d454d89abb4f9a80ff283629401;hpb=c39e08cb2a8d5666f9d54af7d243fa525214d24e;p=simgear.git

diff --git a/simgear/math/vector.cxx b/simgear/math/vector.cxx
index c67ff8ff..a5d3ee0a 100644
--- 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.
 //
 // $Id$
 
@@ -30,6 +29,20 @@
 #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,
@@ -41,8 +54,7 @@ void sgClosestPointToLine( sgVec3 p1, const sgVec3 p, const sgVec3 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) );
+    sgProjection(u1, u, d);
 
     // calculate the point p1 along the line that is closest to p
     // p0 = p1 + u1
@@ -61,12 +73,7 @@ void sgdClosestPointToLine( sgdVec3 p1, const sgdVec3 p, const sgdVec3 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);;
+    sgProjection(u1, u, d);
 
     // calculate the point p1 along the line that is closest to p
     // p0 = p1 + u1
@@ -85,8 +92,7 @@ double sgClosestPointToLineDistSquared( const sgVec3 p, const sgVec3 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) );
+    sgProjection(u1, u, d);
 
     // v = u - u1 = vector from closest point on line, p1, to the
     // original point, p.
@@ -107,12 +113,7 @@ double sgdClosestPointToLineDistSquared( const sgdVec3 p, const sgdVec3 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);;
+    sgProjection(u1, u, d);
 
     // v = u - u1 = vector from closest point on line, p1, to the
     // original point, p.