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Diffstat (limited to 'boost/geometry/strategies/cartesian/buffer_point_circle.hpp')
-rw-r--r-- | boost/geometry/strategies/cartesian/buffer_point_circle.hpp | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/boost/geometry/strategies/cartesian/buffer_point_circle.hpp b/boost/geometry/strategies/cartesian/buffer_point_circle.hpp new file mode 100644 index 0000000000..f64a82d8fc --- /dev/null +++ b/boost/geometry/strategies/cartesian/buffer_point_circle.hpp @@ -0,0 +1,108 @@ +// Boost.Geometry (aka GGL, Generic Geometry Library) +// Copyright (c) 2012-2014 Barend Gehrels, Amsterdam, the Netherlands. +// Use, modification and distribution is subject to 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) + +#ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_POINT_CIRCLE_HPP +#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_POINT_CIRCLE_HPP + +#include <cstddef> + +#include <boost/range.hpp> + +#include <boost/geometry/util/math.hpp> + +#include <boost/geometry/strategies/buffer.hpp> + + +namespace boost { namespace geometry +{ + +namespace strategy { namespace buffer +{ + +/*! +\brief Create a circular buffer around a point +\ingroup strategies +\details This strategy can be used as PointStrategy for the buffer algorithm. + It creates a circular buffer around a point. It can be applied + for points and multi_points, but also for a linestring (if it is degenerate, + so consisting of only one point) and for polygons (if it is degenerate). + This strategy is only applicable for Cartesian coordinate systems. + +\qbk{ +[heading Example] +[buffer_point_circle] +[heading Output] +[$img/strategies/buffer_point_circle.png] +[heading See also] +\* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)] +\* [link geometry.reference.strategies.strategy_buffer_point_square point_square] +} + */ +class point_circle +{ +public : + //! \brief Constructs the strategy + //! \param count number of points for the created circle + explicit point_circle(std::size_t count = 90) + : m_count(count) + {} + +#ifndef DOXYGEN_SHOULD_SKIP_THIS + //! Fills output_range with a circle around point using distance_strategy + template + < + typename Point, + typename OutputRange, + typename DistanceStrategy + > + inline void apply(Point const& point, + DistanceStrategy const& distance_strategy, + OutputRange& output_range) const + { + typedef typename boost::range_value<OutputRange>::type output_point_type; + + typedef typename geometry::select_most_precise + < + typename geometry::select_most_precise + < + typename geometry::coordinate_type<Point>::type, + typename geometry::coordinate_type<output_point_type>::type + >::type, + double + >::type promoted_type; + + promoted_type const buffer_distance = distance_strategy.apply(point, point, + strategy::buffer::buffer_side_left); + + promoted_type const two = 2.0; + promoted_type const two_pi = two * geometry::math::pi<promoted_type>(); + + promoted_type const diff = two_pi / promoted_type(m_count); + promoted_type a = 0; + + for (std::size_t i = 0; i < m_count; i++, a -= diff) + { + output_point_type p; + set<0>(p, get<0>(point) + buffer_distance * cos(a)); + set<1>(p, get<1>(point) + buffer_distance * sin(a)); + output_range.push_back(p); + } + + // Close it: + output_range.push_back(output_range.front()); + } +#endif // DOXYGEN_SHOULD_SKIP_THIS + +private : + std::size_t m_count; +}; + + +}} // namespace strategy::buffer + +}} // namespace boost::geometry + +#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_POINT_CIRCLE_HPP |