text: //---------------------------------------------------------------------------//
  // Copyright (c) 2013-2014 Kyle Lutz <kyle.r.lutz@gmail.com>
  //
  // Distributed under the Boost Software License, Version 1.0
  // See accompanying file LICENSE_1_0.txt or copy at
  // http://www.boost.org/LICENSE_1_0.txt
  //
  // See http://boostorg.github.com/compute for more information.
  //---------------------------------------------------------------------------//
  
  #ifndef BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP
  #define BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP
  
  #include <vector>
  #include <iterator>
  
  #include <boost/compute/system.hpp>
  #include <boost/compute/command_queue.hpp>
  #include <boost/compute/algorithm/copy_n.hpp>
  #include <boost/compute/algorithm/reduce.hpp>
  #include <boost/compute/container/array.hpp>
  
  namespace boost {
  namespace compute {
  
  /// Calculates the bounds for the points in the range [\p first, \p last) and
  /// stores the result in \p bounds.
  ///
  /// For example, this can be used to implement the GetBounds() method for a
  /// vtkMapper subclass.
  template<class PointIterator>
  inline void vtk_compute_bounds(PointIterator first,
                                 PointIterator last,
                                 double bounds[6],
                                 command_queue &queue = system::default_queue())
  {
      typedef typename std::iterator_traits<PointIterator>::value_type T;
  
      const context &context = queue.get_context();
  
      // compute min and max point
      array<T, 2> extrema(context);
      reduce(first, last, extrema.begin() + 0, min<T>(), queue);
      reduce(first, last, extrema.begin() + 1, max<T>(), queue);
  
      // copy results to host buffer
      std::vector<T> buffer(2);
      copy_n(extrema.begin(), 2, buffer.begin(), queue);
  
      // copy to vtk-style bounds
      bounds[0] = buffer[0][0]; bounds[1] = buffer[1][0];
      bounds[2] = buffer[0][1]; bounds[3] = buffer[1][1];
      bounds[4] = buffer[0][2]; bounds[5] = buffer[1][2];
  }
  
  } // end compute namespace
  } // end boost namespace
  
  #endif // BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP
  