Add a simple class to subdivide Bezier curves

projects/VC7.1/SimGear.vcproj

@@ -287,6 +287,9 @@
 		<Filter
 			Name="Lib_sgmath"
 			Filter="">
+			<File
+				RelativePath="..\..\simgear\math\beziercurve.hxx">
+			</File>
 			<File
 				RelativePath="..\..\simgear\math\interpolater.cxx">
 			</File>

simgear/math/Makefile.am

@@ -42,7 +42,8 @@ include_HEADERS = \
 	SGTriangle.hxx \
 	SGVec2.hxx \
 	SGVec3.hxx \
-	SGVec4.hxx
+	SGVec4.hxx \
+	beziercurve.hxx
 
 libsgmath_a_SOURCES = \
 	interpolater.cxx \

simgear/math/beziercurve.hxx

@@ -0,0 +1,105 @@
+/* -*-c++-*-
+ *
+ * Copyright (C) 2009 Frederic Bouvier
+ *
+ * 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 program 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.
+ *
+ * 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.
+ *
+ */
+
+#ifndef SIMGEAR_BEZIERCURVE_HXX
+#define SIMGEAR_BEZIERCURVE_HXX 1
+
+#include <list>
+using std::list;
+
+namespace simgear
+{
+  template<class T>
+  class BezierCurve {
+  public:
+    typedef list<T> PointList;
+
+    BezierCurve() : mMaxSubdiv( 3 ) {}
+    BezierCurve( size_t aMaxSubdiv )
+      : mMaxSubdiv( aMaxSubdiv ) {}
+    BezierCurve( const T &p1, const T &p2, const T &p3, size_t aMaxSubdiv = 3 )
+      : mMaxSubdiv( aMaxSubdiv ) {
+        subdivide( p1, p2, p3 );
+      }
+    BezierCurve( const T &p1, const T &p2, const T &p3, const T &p4, size_t aMaxSubdiv = 3 )
+      : mMaxSubdiv( aMaxSubdiv ) {
+        subdivide( p1, p2, p3, p4 );
+      }
+
+    void subdivide( const T &p1, const T &p2, const T &p3 ) {
+      mPointList.clear();
+      mPointList.push_back( p1 );
+      recursiveSubdivide( p1, p2, p3, 1 );
+      mPointList.push_back( p3 );
+    }
+
+    void subdivide( const T &p1, const T &p2, const T &p3, const T &p4 ) {
+      mPointList.clear();
+      mPointList.push_back( p1 );
+      recursiveSubdivide( p1, p2, p3, p4, 1 );
+      mPointList.push_back( p4 );
+    }
+
+    void setMaxSubdiv( size_t aMaxSubdiv ) { mMaxSubdiv = aMaxSubdiv; }
+    void getMaxSubdiv() const { return mMaxSubdiv; }
+    PointList &pointList() { return mPointList; }
+    const PointList &pointList() const { return mPointList; }
+
+  private:
+    T midPoint( const T &p1, const T &p2 ) {
+      return ( p1 + p2 ) / 2;
+    }
+    bool recursiveSubdivide( const T &p1, const T &p2, const T &p3, size_t l ) {
+      if ( l > mMaxSubdiv )
+        return false;
+
+      T p12 = midPoint( p1, p2 ),
+        p23 = midPoint( p2, p3 ),
+        p123 = midPoint( p12, p23 );
+      recursiveSubdivide( p1, p12, p123, l + 1 );
+      mPointList.push_back( p123 );
+      recursiveSubdivide( p123, p23, p3, l + 1 );
+      return true;
+    }
+
+    bool recursiveSubdivide( const T &p1, const T &p2, const T &p3, const T &p4, size_t l ) {
+      if ( l > mMaxSubdiv )
+        return false;
+
+      T p12 = midPoint( p1, p2 ),
+        p23 = midPoint( p2, p3 ),
+        p34 = midPoint( p3, p4 ),
+        p123 = midPoint( p12, p23 ),
+        p234 = midPoint( p23, p34 ),
+        p1234 = midPoint( p123, p234 );
+      recursiveSubdivide( p1, p12, p123, p1234, l + 1 );
+      mPointList.push_back( p1234 );
+      recursiveSubdivide( p1234, p234, p34, p4, l + 1 );
+      return true;
+    }
+
+
+    PointList mPointList;
+    size_t mMaxSubdiv;
+  };
+}
+
+#endif