Chris@102: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@102: // Copyright (c) 2012-2014 Barend Gehrels, Amsterdam, the Netherlands.
Chris@102: // Use, modification and distribution is subject to the Boost Software License,
Chris@102: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@102: // http://www.boost.org/LICENSE_1_0.txt)
Chris@102: 
Chris@102: #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP
Chris@102: #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP
Chris@102: 
Chris@102: #include <cstddef>
Chris@102: 
Chris@102: #include <boost/geometry/core/coordinate_type.hpp>
Chris@102: #include <boost/geometry/core/access.hpp>
Chris@102: #include <boost/geometry/util/math.hpp>
Chris@102: #include <boost/geometry/util/select_most_precise.hpp>
Chris@102: 
Chris@102: #include <boost/geometry/strategies/buffer.hpp>
Chris@102: #include <boost/geometry/strategies/side.hpp>
Chris@102: 
Chris@102: 
Chris@102: 
Chris@102: namespace boost { namespace geometry
Chris@102: {
Chris@102: 
Chris@102: namespace strategy { namespace buffer
Chris@102: {
Chris@102: 
Chris@102: 
Chris@102: 
Chris@102: /*!
Chris@102: \brief Let the buffer use straight sides along segments (the default)
Chris@102: \ingroup strategies
Chris@102: \details This strategy can be used as SideStrategy for the buffer algorithm.
Chris@102:     It is currently the only provided strategy for this purpose
Chris@102: 
Chris@102: \qbk{
Chris@102: [heading Example]
Chris@102: See the examples for other buffer strategies\, for example
Chris@102: [link geometry.reference.strategies.strategy_buffer_join_round join_round]
Chris@102: [heading See also]
Chris@102: \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)]
Chris@102: }
Chris@102:  */
Chris@102: class side_straight
Chris@102: {
Chris@102: public :
Chris@102: #ifndef DOXYGEN_SHOULD_SKIP_THIS
Chris@102:     template
Chris@102:     <
Chris@102:         typename Point,
Chris@102:         typename OutputRange,
Chris@102:         typename DistanceStrategy
Chris@102:     >
Chris@102:     static inline void apply(
Chris@102:                 Point const& input_p1, Point const& input_p2,
Chris@102:                 strategy::buffer::buffer_side_selector side,
Chris@102:                 DistanceStrategy const& distance,
Chris@102:                 OutputRange& output_range)
Chris@102:     {
Chris@102:         typedef typename coordinate_type<Point>::type coordinate_type;
Chris@102:         typedef typename geometry::select_most_precise
Chris@102:         <
Chris@102:             coordinate_type,
Chris@102:             double
Chris@102:         >::type promoted_type;
Chris@102: 
Chris@102:         // Generate a block along (left or right of) the segment
Chris@102: 
Chris@102:         // Simulate a vector d (dx,dy)
Chris@102:         coordinate_type const dx = get<0>(input_p2) - get<0>(input_p1);
Chris@102:         coordinate_type const dy = get<1>(input_p2) - get<1>(input_p1);
Chris@102: 
Chris@102:         // For normalization [0,1] (=dot product d.d, sqrt)
Chris@102:         promoted_type const length = geometry::math::sqrt(dx * dx + dy * dy);
Chris@102: 
Chris@102:         if (geometry::math::equals(length, 0))
Chris@102:         {
Chris@102:             // Coordinates are simplified and therefore most often not equal.
Chris@102:             // But if simplify is skipped, or for lines with two
Chris@102:             // equal points, length is 0 and we cannot generate output.
Chris@102:             return;
Chris@102:         }
Chris@102: 
Chris@102:         // Generate the normalized perpendicular p, to the left (ccw)
Chris@102:         promoted_type const px = -dy / length;
Chris@102:         promoted_type const py = dx / length;
Chris@102: 
Chris@102:         promoted_type const d = distance.apply(input_p1, input_p2, side);
Chris@102: 
Chris@102:         output_range.resize(2);
Chris@102: 
Chris@102:         set<0>(output_range.front(), get<0>(input_p1) + px * d);
Chris@102:         set<1>(output_range.front(), get<1>(input_p1) + py * d);
Chris@102:         set<0>(output_range.back(), get<0>(input_p2) + px * d);
Chris@102:         set<1>(output_range.back(), get<1>(input_p2) + py * d);
Chris@102:     }
Chris@102: #endif // DOXYGEN_SHOULD_SKIP_THIS
Chris@102: };
Chris@102: 
Chris@102: 
Chris@102: }} // namespace strategy::buffer
Chris@102: 
Chris@102: }} // namespace boost::geometry
Chris@102: 
Chris@102: #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_SIDE_STRAIGHT_HPP