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 Hu Chunming
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// 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_HPP
#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_HPP
namespace boost { namespace geometry
{
namespace strategy { namespace buffer
{
/*
A Buffer-join strategy gets 4 input points.
On the two consecutive segments s1 and s2 (joining at vertex v):
The lines from parallel at s1, s2 (at buffer-distance) end/start
in two points perpendicular to the segments: p1 and p2.
These parallel lines interesct in point ip
(s2)
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^
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(p2) |(v)
* +----<--- (s1)
x(ip) *(p1)
So, in clockwise order:
v : vertex point
p1: perpendicular on left side of segment1<1> (perp1)
ip: intersection point
p2: perpendicular on left side of segment2<0> (perp2)
*/
/*!
\brief Enumerates options for side of buffer (left/right w.r.t. directed
segment)
\ingroup enum
\details Around a linestring, a buffer can be defined left or right.
Around a polygon, assumed clockwise internally,
a buffer is either on the left side (inflates the polygon), or on the
right side (deflates the polygon)
*/
enum buffer_side_selector { buffer_side_left, buffer_side_right };
/*!
\brief Enumerates types of pieces (parts of buffer) around geometries
\ingroup enum
*/
enum piece_type
{
buffered_segment,
buffered_join,
buffered_round_end,
buffered_flat_end,
buffered_point,
buffered_concave, // always on the inside
buffered_empty_side, // for one-sided buffers
piece_type_unknown
};
/*!
\brief Enumerates types of joins
\ingroup enum
*/
enum join_selector
{
join_convex,
join_concave,
join_continue, // collinear, next segment touches previous segment
join_spike // collinear, with overlap, next segment goes back
};
/*!
\brief Enumerates types of result codes from buffer strategies
\ingroup enum
*/
enum result_code
{
result_normal,
result_error_numerical,
result_no_output
};
}} // namespace strategy::buffer
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_HPP
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