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#pragma once
#include <mapbox/geojsonvt/simplify.hpp>
#include <mapbox/geojsonvt/types.hpp>
#include <mapbox/geometry.hpp>
#include <algorithm>
#include <cmath>
namespace mapbox {
namespace geojsonvt {
namespace detail {
struct project {
const double tolerance;
using result_type = vt_geometry;
vt_point operator()(const geometry::point<double>& p) {
const double sine = std::sin(p.y * M_PI / 180);
const double x = p.x / 360 + 0.5;
const double y =
std::max(std::min(0.5 - 0.25 * std::log((1 + sine) / (1 - sine)) / M_PI, 1.0), 0.0);
return { x, y, 0.0 };
}
vt_line_string operator()(const geometry::line_string<double>& points) {
vt_line_string result;
const size_t len = points.size();
if (len == 0)
return result;
result.reserve(len);
for (const auto& p : points) {
result.push_back(operator()(p));
}
for (size_t i = 0; i < len - 1; ++i) {
const auto& a = result[i];
const auto& b = result[i + 1];
// use Manhattan distance instead of Euclidian to avoid expensive square root
// computation
result.dist += std::abs(b.x - a.x) + std::abs(b.y - a.y);
}
simplify(result, tolerance);
return result;
}
vt_linear_ring operator()(const geometry::linear_ring<double>& ring) {
vt_linear_ring result;
const size_t len = ring.size();
if (len == 0)
return result;
result.reserve(len);
for (const auto& p : ring) {
result.push_back(operator()(p));
}
double area = 0.0;
for (size_t i = 0; i < len - 1; ++i) {
const auto& a = result[i];
const auto& b = result[i + 1];
area += a.x * b.y - b.x * a.y;
}
result.area = std::abs(area / 2);
simplify(result, tolerance);
return result;
}
vt_geometry operator()(const geometry::geometry<double>& geometry) {
return geometry::geometry<double>::visit(geometry, project{ tolerance });
}
// Handles polygon, multi_*, geometry_collection.
template <class T>
auto operator()(const T& vector) {
typename vt_geometry_type<T>::type result;
result.reserve(vector.size());
for (const auto& e : vector) {
result.push_back(operator()(e));
}
return result;
}
};
inline vt_features convert(const geometry::feature_collection<double>& features,
const double tolerance) {
vt_features projected;
projected.reserve(features.size());
for (const auto& feature : features) {
projected.emplace_back(
geometry::geometry<double>::visit(feature.geometry, project{ tolerance }),
feature.properties,
feature.id);
}
return projected;
}
} // namespace detail
} // namespace geojsonvt
} // namespace mapbox
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