# HG changeset patch
# User alpar
# Date 1105914686 0
# Node ID 320a0f083ca13166bfa7f70240ebf7adee8dce37
# Parent  8043b93e5973f884b7429ddb27f71a0ef274337b
Functions added to compute the gradient of Bezier curve.

diff -r 8043b93e5973 -r 320a0f083ca1 src/lemon/bezier.h
--- a/src/lemon/bezier.h	Sun Jan 16 22:29:28 2005 +0000
+++ b/src/lemon/bezier.h	Sun Jan 16 22:31:26 2005 +0000
@@ -21,7 +21,7 @@
 ///\file
 ///\brief Classes to compute with Bezier curves.
 ///
-///Up to now this file is internally used by \ref graph_to_eps.h
+///Up to now this file is used internally by \ref graph_to_eps.h
 ///
 ///\author Alpar Juttner
 
@@ -58,7 +58,11 @@
   {
     return Bezier1(conv(p1,p2,t),p2);
   }
-  Bezier1 operator()(double a,double b) { return before(b).after(a/b); }  
+  Bezier1 revert() { return Bezier1(p2,p1);}
+  Bezier1 operator()(double a,double b) { return before(b).after(a/b); }
+  xy grad() { return p2-p1; }
+  xy grad(double t) { return grad(); }
+
 };
 
 class Bezier2 : public BezierBase
@@ -87,8 +91,10 @@
     xy r(conv(p2,p3,t));
     return Bezier2(conv(q,r,t),r,p3);
   }
+  Bezier2 revert() { return Bezier2(p3,p2,p1);}
   Bezier2 operator()(double a,double b) { return before(b).after(a/b); }
-  
+  Bezier1 grad() { return Bezier1(2.0*(p2-p1),2.0*(p3-p2)); }
+  xy grad(double t) { return grad()(t); }  
 };
 
 class Bezier3 : public BezierBase
@@ -130,8 +136,10 @@
       xy c(conv(a,b,t));
       return Bezier3(c,b,r,p4);
     }
+  Bezier3 revert() { return Bezier3(p4,p3,p2,p1);}
   Bezier3 operator()(double a,double b) { return before(b).after(a/b); }
-  
+  Bezier2 grad() { return Bezier2(3.0*(p2-p1),3.0*(p3-p2),3.0*(p4-p3)); }
+  xy grad(double t) { return grad()(t); }
 };
 
 } //END OF NAMESPACE LEMON