X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=simgear%2Fmath%2Fvector.cxx;h=a5d3ee0a6c2337efb583c2a53b5f6ac4a649d94e;hb=f19e83dcf10d5fced3d799c884a4654d7ada6548;hp=7c6f2c3cb46296eca6978968682cee5d4ea666ed;hpb=2ed07850c616705695f2add269d187f981f8d09d;p=simgear.git

diff --git a/simgear/math/vector.cxx b/simgear/math/vector.cxx
index 7c6f2c3c..a5d3ee0a 100644
--- a/simgear/math/vector.cxx
+++ b/simgear/math/vector.cxx
@@ -2,21 +2,21 @@
 //
 // 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 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 library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library 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
+// This library 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.
+// Library 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.
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 //
 // $Id$
 
@@ -29,10 +29,62 @@
 #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;
     
@@ -40,8 +92,7 @@ double sgPointLineDistSquared( 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.
@@ -53,22 +104,16 @@ 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;
-
-    sgdScaleVec3(u1, d, tmp);;
+    sgProjection(u1, u, d);
 
     // v = u - u1 = vector from closest point on line, p1, to the
     // original point, p.