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% | Reference manual page: orientation_2.tex
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% | 21.06.2001   Author
% | Package: Polygon
% | 
\RCSdef{\RCSorientationRev}{$Id$}
\RCSdefDate{\RCSorientationDate}{$Date$}
% |
%%RefPage: end of header, begin of main body
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\begin{ccRefFunction}{orientation_2}  %% add template arg's if necessary

%% \ccHtmlCrossLink{}     %% add further rules for cross referencing links
%% \ccHtmlIndexC[function]{} %% add further index entries

\ccDefinition
  
The function \ccRefName\ computes if a polygon is clockwise or counterclockwise
oriented.

\ccInclude{CGAL/Polygon_2_algorithms.h}

\ccGlobalFunction{
template <class ForwardIterator, class Traits>
Orientation orientation_2(ForwardIterator first, ForwardIterator last,
                                    const Traits& traits);}
{
\ccPrecond \ccc{is_simple_2(first, last, traits);}
}


\ccHeading{Requirements}
\ccIndexSubitem[C]{bottom_vertex_2}{requirements}
\begin{enumerate}
    \item \ccc{Traits} is a model of the concept 
	  PolygonTraits\_2\ccIndexMainItem[c]{PolygonTraits_2}.
	  Only the following members of this traits class are used:
          \begin{itemize}
            \item \ccc{Less_xy_2}
            \item \ccc{less_xy_2_object}
            \item \ccc{orientation_2_object}
          \end{itemize}
    \item \ccc{ForwardIterator::value_type} should be \ccc{Traits::Point_2},
\end{enumerate}


\ccSeeAlso

\ccRefIdfierPage{PolygonTraits_2} \\
\ccRefIdfierPage{CGAL::is_simple_2} \\
\ccRefIdfierPage{CGAL::Polygon_2<PolygonTraits_2, Container>} \\
\ccc{CGAL::Orientation}

%% \ccIncludeExampleCode{Polygon/orientation_2_prog.cpp}

\end{ccRefFunction}

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