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Fix #388 by using Boost.Geometry

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"crosses" fits the requirement as it means that the interior parts of the
geometry share some common points, not exterior parts such as
end-points, and it means "not within".
This commit is contained in:
Jeremy W. Murphy
2024-12-19 08:39:12 +11:00
parent 8a60b5a259
commit 87b862c191
1 changed files with 19 additions and 70 deletions
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include/boost/graph/is_straight_line_drawing.hpp
+19 -70
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@@ -16,75 +16,16 @@
#include <boost/graph/properties.hpp>
#include <boost/graph/planar_detail/bucket_sort.hpp>
#include <boost/geometry/algorithms/crosses.hpp>
#include <boost/geometry/geometries/linestring.hpp>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
namespace boost
{
// Return true exactly when the line segments s1 = ((x1,y1), (x2,y2)) and
// s2 = ((a1,b1), (a2,b2)) intersect in a point other than the endpoints of
// the line segments. The one exception to this rule is when s1 = s2, in
// which case false is returned - this is to accomodate multiple edges
// between the same pair of vertices, which shouldn't invalidate the straight
// line embedding. A tolerance variable epsilon can also be used, which
// defines how far away from the endpoints of s1 and s2 we want to consider
// an intersection.
inline bool intersects(double x1, double y1, double x2, double y2, double a1,
double b1, double a2, double b2, double epsilon = 0.000001)
{
if (x1 - x2 == 0)
{
std::swap(x1, a1);
std::swap(y1, b1);
std::swap(x2, a2);
std::swap(y2, b2);
}
if (x1 - x2 == 0)
{
BOOST_USING_STD_MAX();
BOOST_USING_STD_MIN();
// two vertical line segments
double min_y = min BOOST_PREVENT_MACRO_SUBSTITUTION(y1, y2);
double max_y = max BOOST_PREVENT_MACRO_SUBSTITUTION(y1, y2);
double min_b = min BOOST_PREVENT_MACRO_SUBSTITUTION(b1, b2);
double max_b = max BOOST_PREVENT_MACRO_SUBSTITUTION(b1, b2);
if ((max_y > max_b && max_b > min_y)
|| (max_b > max_y && max_y > min_b))
return true;
else
return false;
}
double x_diff = x1 - x2;
double y_diff = y1 - y2;
double a_diff = a2 - a1;
double b_diff = b2 - b1;
double beta_denominator = b_diff - (y_diff / ((double)x_diff)) * a_diff;
if (beta_denominator == 0)
{
// parallel lines
return false;
}
double beta = (b2 - y2 - (y_diff / ((double)x_diff)) * (a2 - x2))
/ beta_denominator;
double alpha = (a2 - x2 - beta * (a_diff)) / x_diff;
double upper_bound = 1 - epsilon;
double lower_bound = 0 + epsilon;
return (beta < upper_bound && beta > lower_bound && alpha < upper_bound
&& alpha > lower_bound);
}
template < typename Graph, typename GridPositionMap, typename VertexIndexMap >
bool is_straight_line_drawing(
@@ -152,6 +93,10 @@ bool is_straight_line_drawing(
}
else
{
using geometry::crosses;
using geometry::model::linestring;
using geometry::model::d2::point_xy;
active_map_iterator_t before, after;
if (a_itr == active_edges.begin())
before = active_edges.end();
@@ -168,10 +113,12 @@ bool is_straight_line_drawing(
vertex_t f_source(source(f, g));
vertex_t f_target(target(f, g));
if (intersects(drawing[e_source].x, drawing[e_source].y,
drawing[e_target].x, drawing[e_target].y,
drawing[f_source].x, drawing[f_source].y,
drawing[f_target].x, drawing[f_target].y))
linestring<point_xy<double>> source{{drawing[e_source].x, drawing[e_source].y},
{drawing[e_target].x, drawing[e_target].y}};
linestring<point_xy<double>> target{{drawing[f_source].x, drawing[f_source].y},
{drawing[f_target].x, drawing[f_target].y}};
if (crosses(source, target))
return false;
}
@@ -184,10 +131,12 @@ bool is_straight_line_drawing(
vertex_t f_source(source(f, g));
vertex_t f_target(target(f, g));
if (intersects(drawing[e_source].x, drawing[e_source].y,
drawing[e_target].x, drawing[e_target].y,
drawing[f_source].x, drawing[f_source].y,
drawing[f_target].x, drawing[f_target].y))
linestring<point_xy<double>> source{{drawing[e_source].x, drawing[e_source].y},
{drawing[e_target].x, drawing[e_target].y}};
linestring<point_xy<double>> target{{drawing[f_source].x, drawing[f_source].y},
{drawing[f_target].x, drawing[f_target].y}};
if (crosses(source, target))
return false;
}