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https://github.com/mapbox/tippecanoe.git
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80 lines
2.4 KiB
C++
80 lines
2.4 KiB
C++
#pragma once
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#include <cmath>
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#include <mapbox/geometry/point.hpp>
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#include <mapbox/geometry/polygon.hpp>
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#include <mapbox/geometry/wagyu/point.hpp>
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namespace mapbox {
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namespace geometry {
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namespace wagyu {
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template <typename T>
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double area(mapbox::geometry::linear_ring<T> const& poly) {
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std::size_t size = poly.size();
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if (size < 3) {
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return 0.0;
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}
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double a = 0.0;
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auto itr = poly.begin();
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auto itr_prev = poly.end();
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--itr_prev;
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a += static_cast<double>(itr_prev->x + itr->x) * static_cast<double>(itr_prev->y - itr->y);
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++itr;
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itr_prev = poly.begin();
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for (; itr != poly.end(); ++itr, ++itr_prev) {
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a += static_cast<double>(itr_prev->x + itr->x) * static_cast<double>(itr_prev->y - itr->y);
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}
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return -a * 0.5;
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}
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inline bool value_is_zero(double val) {
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return std::fabs(val) < std::numeric_limits<double>::epsilon();
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}
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inline bool values_are_equal(double x, double y) {
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return value_is_zero(x - y);
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}
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inline bool values_near_equal(double x, double y) {
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return std::fabs(x - y) < (5.0 * std::numeric_limits<double>::epsilon());
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}
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inline bool greater_than_or_equal(double x, double y) {
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return x > y || values_are_equal(x, y);
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}
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template <typename T>
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bool slopes_equal(mapbox::geometry::point<T> const& pt1,
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mapbox::geometry::point<T> const& pt2,
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mapbox::geometry::point<T> const& pt3) {
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return (pt1.y - pt2.y) * (pt2.x - pt3.x) == (pt1.x - pt2.x) * (pt2.y - pt3.y);
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}
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template <typename T>
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bool slopes_equal(mapbox::geometry::wagyu::point<T> const& pt1,
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mapbox::geometry::wagyu::point<T> const& pt2,
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mapbox::geometry::point<T> const& pt3) {
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return (pt1.y - pt2.y) * (pt2.x - pt3.x) == (pt1.x - pt2.x) * (pt2.y - pt3.y);
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}
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template <typename T>
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bool slopes_equal(mapbox::geometry::wagyu::point<T> const& pt1,
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mapbox::geometry::wagyu::point<T> const& pt2,
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mapbox::geometry::wagyu::point<T> const& pt3) {
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return (pt1.y - pt2.y) * (pt2.x - pt3.x) == (pt1.x - pt2.x) * (pt2.y - pt3.y);
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}
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template <typename T>
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bool slopes_equal(mapbox::geometry::point<T> const& pt1,
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mapbox::geometry::point<T> const& pt2,
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mapbox::geometry::point<T> const& pt3,
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mapbox::geometry::point<T> const& pt4) {
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return (pt1.y - pt2.y) * (pt3.x - pt4.x) == (pt1.x - pt2.x) * (pt3.y - pt4.y);
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}
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}
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}
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}
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