ceph/src/boost/libs/compute/include/boost/compute/interop/vtk/bounds.hpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2013-2014 Kyle Lutz <kyle.r.lutz@gmail.com>
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 // See http://boostorg.github.com/compute for more information.
   9 //---------------------------------------------------------------------------//
  10
  11 #ifndef BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP
  12 #define BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP
  13
  14 #include <vector>
  15 #include <iterator>
  16
  17 #include <boost/compute/system.hpp>
  18 #include <boost/compute/command_queue.hpp>
  19 #include <boost/compute/algorithm/copy_n.hpp>
  20 #include <boost/compute/algorithm/reduce.hpp>
  21 #include <boost/compute/container/array.hpp>
  22
  23 namespace boost {
  24 namespace compute {
  25
  26 /// Calculates the bounds for the points in the range [\p first, \p last) and
  27 /// stores the result in \p bounds.
  28 ///
  29 /// For example, this can be used to implement the GetBounds() method for a
  30 /// vtkMapper subclass.
  31 template<class PointIterator>
  32 inline void vtk_compute_bounds(PointIterator first,
  33                                PointIterator last,
  34                                double bounds[6],
  35                                command_queue &queue = system::default_queue())
  36 {
  37     typedef typename std::iterator_traits<PointIterator>::value_type T;
  38
  39     const context &context = queue.get_context();
  40
  41     // compute min and max point
  42     array<T, 2> extrema(context);
  43     reduce(first, last, extrema.begin() + 0, min<T>(), queue);
  44     reduce(first, last, extrema.begin() + 1, max<T>(), queue);
  45
  46     // copy results to host buffer
  47     std::vector<T> buffer(2);
  48     copy_n(extrema.begin(), 2, buffer.begin(), queue);
  49
  50     // copy to vtk-style bounds
  51     bounds[0] = buffer[0][0]; bounds[1] = buffer[1][0];
  52     bounds[2] = buffer[0][1]; bounds[3] = buffer[1][1];
  53     bounds[4] = buffer[0][2]; bounds[5] = buffer[1][2];
  54 }
  55
  56 } // end compute namespace
  57 } // end boost namespace
  58
  59 #endif // BOOST_COMPUTE_INTEROP_VTK_BOUNDS_HPP