/usr/include/mapbox/geometry/wagyu/build_edges.hpp is in libmapbox-wagyu-dev 0.4.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 | #pragma once
#include <mapbox/geometry/line_string.hpp>
#include <mapbox/geometry/point.hpp>
#include <mapbox/geometry/polygon.hpp>
#include <mapbox/geometry/wagyu/config.hpp>
#include <mapbox/geometry/wagyu/edge.hpp>
#include <mapbox/geometry/wagyu/util.hpp>
namespace mapbox {
namespace geometry {
namespace wagyu {
template <typename T>
bool point_2_is_between_point_1_and_point_3(mapbox::geometry::point<T> const& pt1,
mapbox::geometry::point<T> const& pt2,
mapbox::geometry::point<T> const& pt3) {
if ((pt1 == pt3) || (pt1 == pt2) || (pt3 == pt2)) {
return false;
} else if (pt1.x != pt3.x) {
return (pt2.x > pt1.x) == (pt2.x < pt3.x);
} else {
return (pt2.y > pt1.y) == (pt2.y < pt3.y);
}
}
template <typename T1, typename T2>
bool build_edge_list(mapbox::geometry::linear_ring<T2> const& path_geometry, edge_list<T1>& edges) {
if (path_geometry.size() < 3) {
return false;
}
// As this is a loop, we need to first go backwards from end to try and find
// the proper starting point for the iterators before the beginning
auto itr_rev = path_geometry.rbegin();
auto itr = path_geometry.begin();
mapbox::geometry::point<T2> pt1 = *itr_rev;
mapbox::geometry::point<T2> pt2 = *itr;
// Find next non repeated point going backwards from
// end for pt1
while (pt1 == pt2) {
++itr_rev;
if (itr_rev == path_geometry.rend()) {
return false;
}
pt1 = *itr_rev;
}
++itr;
mapbox::geometry::point<T2> pt3 = *itr;
auto itr_last = itr_rev.base();
mapbox::geometry::point<T2> front_pt;
mapbox::geometry::point<T2> back_pt;
while (true) {
if (pt3 == pt2) {
// Duplicate point advance itr, but do not
// advance other points
if (itr == itr_last) {
break;
}
++itr;
if (itr == itr_last) {
if (edges.empty()) {
break;
}
pt3 = front_pt;
} else {
pt3 = *itr;
}
continue;
}
// Now check if slopes are equal between two segments - either
// a spike or a collinear point - if so drop point number 2.
if (slopes_equal(pt1, pt2, pt3)) {
// We need to reconsider previously added points
// because the point it was using was found to be collinear
// or a spike
pt2 = pt1;
if (!edges.empty()) {
edges.pop_back(); // remove previous edge (pt1)
}
if (!edges.empty()) {
auto const& back_top = edges.back().top;
if (static_cast<T1>(back_pt.x) == back_top.x &&
static_cast<T1>(back_pt.y) == back_top.y) {
auto const& back_bot = edges.back().bot;
pt1 = mapbox::geometry::point<T2>(static_cast<T2>(back_bot.x),
static_cast<T2>(back_bot.y));
} else {
pt1 = mapbox::geometry::point<T2>(static_cast<T2>(back_top.x),
static_cast<T2>(back_top.y));
}
back_pt = pt1;
} else {
// If this occurs we must look to the back of the
// ring for new points.
while (*itr_rev == pt2) {
++itr_rev;
if ((itr + 1) == itr_rev.base()) {
return false;
}
}
pt1 = *itr_rev;
itr_last = itr_rev.base();
}
continue;
}
if (edges.empty()) {
front_pt = pt2;
}
edges.emplace_back(pt2, pt3);
back_pt = pt2;
if (itr == itr_last) {
break;
}
pt1 = pt2;
pt2 = pt3;
++itr;
if (itr == itr_last) {
if (edges.empty()) {
break;
}
pt3 = front_pt;
} else {
pt3 = *itr;
}
}
bool modified = false;
do {
modified = false;
if (edges.size() < 3) {
return false;
}
auto& f = edges.front();
auto& b = edges.back();
if (slopes_equal(f, b)) {
if (f.bot == b.top) {
if (f.top == b.bot) {
edges.pop_back();
edges.erase(edges.begin());
} else {
f.bot = b.bot;
edges.pop_back();
}
modified = true;
} else if (f.top == b.bot) {
f.top = b.top;
edges.pop_back();
modified = true;
} else if (f.top == b.top && f.bot == b.bot) {
edges.pop_back();
edges.erase(edges.begin());
modified = true;
} else if (f.top == b.top) {
if (point_2_is_between_point_1_and_point_3(f.top, f.bot, b.bot)) {
b.top = f.bot;
edges.erase(edges.begin());
} else {
f.top = b.bot;
edges.pop_back();
}
modified = true;
} else if (f.bot == b.bot) {
if (point_2_is_between_point_1_and_point_3(f.bot, f.top, b.top)) {
b.bot = f.top;
edges.erase(edges.begin());
} else {
f.bot = b.top;
edges.pop_back();
}
modified = true;
}
}
} while (modified);
return true;
}
}
}
}
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