[ADD] Midpoint of fibers

src/math/WLine.cpp

@@ -28,6 +28,7 @@
 
 #include "../common/WLimits.h"
 #include "../common/WStringUtils.h"
+#include "../common/exceptions/WOutOfBounds.h"
 #include "WLine.h"
 #include "WPosition.h"
 
@@ -100,4 +101,13 @@ void WLine::resample( size_t numPoints )
     assert( size() == numPoints && "Resampling of a line has failed! Is your fiber of length 0 or even the new sample rate??" );
 }
 
+const wmath::WPosition& WLine::midPoint() const
+{
+    if( empty() )
+    {
+        throw WOutOfBounds( "There is no midpoint for an empty line." );
+    }
+    return at( ( size() - 1 ) / 2 );
+}
+
 } // end of namespace

src/math/WLine.h

@@ -76,6 +76,17 @@ namespace wmath
          * \return Sum of all line segment lengths
          */
         double pathLength() const;
+
+        /**
+         * Returns the point in the middle of the line. In case of an even sized
+         * line the mid point is the same as if there were only size()-1 many
+         * elements present.
+         *
+         * \throws WOutOfBounds In case its called on an empty line
+         *
+         * \return Const reference to the midpoint element.
+         */
+        const wmath::WPosition& midPoint() const;
     };
 } // end of namespace
 #endif  // WLINE_H

src/math/test/WLine_test.h

@@ -31,8 +31,10 @@
 #include <cxxtest/TestSuite.h>
 
 #include "../../common/WLimits.h"
+#include "../../common/exceptions/WOutOfBounds.h"
 #include "../WLine.h"
 #include "WLineTraits.h"
+#include "WVector3DTraits.h"
 
 /**
  * Unit tests the WLine class
@@ -226,6 +228,51 @@ public:
     //     assert_SAMELINES( expected, line );
     //  }
 
+    /**
+     * The mid point of a WLine is just the point in the middle of the line.
+     * For lines with even numbered size the element before that non existing
+     * midPoint is selected.
+     */
+    void testMidPointOnEvenSize( void )
+    {
+        using wmath::WPosition;
+        wmath::WLine line;
+        line.push_back( WPosition( 0, 0, 0 ) );
+        line.push_back( WPosition( 1, 1, 0 ) );
+        line.push_back( WPosition( 2, 0, 0 ) );
+        line.push_back( WPosition( 3, 1, 0 ) );
+        WPosition expected( 1, 1, 0 );
+        TS_ASSERT_EQUALS( expected, WPosition( line.midPoint() ) );
+    }
+
+    /**
+     * When a line has uneven numbered size, the mid point is unique.
+     */
+    void testMidPointOnUnevenSize( void )
+    {
+        using wmath::WPosition;
+        wmath::WLine line;
+        line.push_back( WPosition( 0, 0, 0 ) );
+        line.push_back( WPosition( 1, 1, 0 ) );
+        line.push_back( WPosition( 2, 0, 0 ) );
+        WPosition expected( 1, 1, 0 );
+        TS_ASSERT_EQUALS( expected, WPosition( line.midPoint() ) );
+    }
+
+    /**
+     * When calling midPoint on empty lines => there is no point to return
+     * hence an exception is generated.
+     */
+    void testMidPointOnEmptyLine( void )
+    {
+        using wmath::WPosition;
+        wmath::WLine line;
+        WPosition expected( 1, 1, 0 );
+        TS_ASSERT_THROWS_EQUALS( line.midPoint(), WOutOfBounds &e, std::string( e.what() ), "There is no midpoint for an empty line." );
+    }
+
+
+
 private:
     /**
      * TS_ASSERT_DELTA needs the operator+, operator- and operator< to be implemented especially for WPositions the operator< and operator +