From 3c53f52f60bf185d76c043566819b9c17ed8ccdf Mon Sep 17 00:00:00 2001
From: Joachim Schoeberl <joachim.schoeberl@tuwien.ac.at>
Date: Tue, 6 Apr 2010 15:00:19 +0000
Subject: [PATCH] fix in revolution primitive (orientation of spline curve)

---
 libsrc/csg/revolution.cpp | 16 ++++++----------
 libsrc/geom2d/spline.hpp  | 14 ++++++++++++--
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/libsrc/csg/revolution.cpp b/libsrc/csg/revolution.cpp
index 3e7da3ca..89863b6d 100644
--- a/libsrc/csg/revolution.cpp
+++ b/libsrc/csg/revolution.cpp
@@ -441,24 +441,20 @@ namespace netgen
 
     int n = int(2.*facets) + 1;
 
-    int i,j;
-    double phi;
-    Point<3> p;
-
-    for(i=0; i<=n; i++)
+    for(int i=0; i<=n; i++)
       {
 	Point<2> sp = spline->GetPoint(double(i)/double(n));
-	for(j=0; j<=n; j++)
+	for(int j=0; j<=n; j++)
 	  {
-	    phi = 2.*M_PI*double(j)/double(n);
+	    double phi = 2.*M_PI*double(j)/double(n);
 	    
-	    p = p0 + sp(0)*v_axis + sp(1)*cos(phi)*v1 + sp(1)*sin(phi)*v2;
+	    Point<3> p = p0 + sp(0)*v_axis + sp(1)*cos(phi)*v1 + sp(1)*sin(phi)*v2;
 	    tas.AddPoint(p);   
 	  }
       }
     
-    for(i=0; i<n; i++)
-      for(j=0; j<n; j++)
+    for(int i=0; i<n; i++)
+      for(int j=0; j<n; j++)
 	{
 	  int pi = (n+1)*i+j;
 
diff --git a/libsrc/geom2d/spline.hpp b/libsrc/geom2d/spline.hpp
index 0b0095e2..4cd70a69 100644
--- a/libsrc/geom2d/spline.hpp
+++ b/libsrc/geom2d/spline.hpp
@@ -610,7 +610,6 @@ Vec<D> SplineSeg3<D> :: GetTangent (const double t) const
 template<int D>
 void SplineSeg3<D> :: GetCoeff (Vector & u) const
 {
-  Point<D> p;
   DenseMatrix a(6, 6);
   DenseMatrix ata(6, 6);
   Vector f(6);
@@ -622,7 +621,7 @@ void SplineSeg3<D> :: GetCoeff (Vector & u) const
   double t = 0;
   for (int i = 0; i < 5; i++, t += 0.25)
     {
-      p = GetPoint (t);
+      Point<D> p = GetPoint (t);
       a(i, 0) = p(0) * p(0);
       a(i, 1) = p(1) * p(1);
       a(i, 2) = p(0) * p(1);
@@ -638,6 +637,17 @@ void SplineSeg3<D> :: GetCoeff (Vector & u) const
   u(5) = 1;
   a.MultTrans (u, f);
   ata.Solve (f, u);
+
+  // the sign
+  Point<D> p0 = GetPoint(0);
+  Vec<D> ht = GetTangent(0);
+  Vec<2> tang(ht(0), ht(1));
+
+  double gradx = 2.*u(0)*p0(0) + u(2)*p0(1) + u(3);
+  double grady = 2.*u(1)*p0(1) + u(2)*p0(0) + u(4);
+  Vec<2> gradn (grady, -gradx);
+  
+  if (tang * gradn < 0) u *= -1;
 }
 
 /*