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#ifndef OPENTISSUE_COLLISION_GJK_GJK_OUTSIDE_TRIANGLE_H
#define OPENTISSUE_COLLISION_GJK_GJK_OUTSIDE_TRIANGLE_H
//
// OpenTissue Template Library
// - A generic toolbox for physics-based modeling and simulation.
// Copyright (C) 2008 Department of Computer Science, University of Copenhagen.
//
// OTTL is licensed under zlib: http://opensource.org/licenses/zlib-license.php
//
#include <OpenTissue/configuration.h>

#include <OpenTissue/core/math/math_is_number.h>

#include <cassert>

namespace OpenTissue
{
  namespace gjk
  {

    namespace detail
    {

      template< typename V >
      inline bool outside_triangle( 
        V const & p
        , V const & A
        , V const & B
        , V const & C
        , V const & q
        )
      {
        typedef typename V::value_traits    value_traits;
        typedef typename V::value_type      T;

        V const n = cross( A-B, C-B );

        assert( dot( n, n ) > value_traits::zero() || !"outside_triangle(): Degenerate triangle encountered");

        T const sign_p = dot( n, p-B );
        T const sign_q = dot( n, q-B );

        assert( is_number( sign_p ) || !"outside_triangle(): Not a Number encountered");
        assert( is_number( sign_q ) || !"outside_triangle(): Not a Number encountered");

        assert( sign_q < value_traits::zero() || sign_q > value_traits::zero() || !"outside_triangle(): q was in plane, can  not be used to determine sign");        

        return (sign_p*sign_q) <= value_traits::zero();
      }

    } // namespace detail

  } // namespace gjk

} // namespace OpenTissue

// OPENTISSUE_COLLISION_GJK_GJK_OUTSIDE_TRIANGLE_H
#endif