82 lines
2.9 KiB
C++
82 lines
2.9 KiB
C++
#include <mbgl/layout/clip_lines.hpp>
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#include <cmath>
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namespace mbgl {
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namespace util {
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GeometryCollection clipLines(
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const GeometryCollection& lines, const int16_t x1, const int16_t y1, const int16_t x2, const int16_t y2) {
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GeometryCollection clippedLines;
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for (auto& line : lines) {
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if (line.empty()) continue;
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auto end = line.end() - 1;
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for (auto it = line.begin(); it != end; it++) {
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GeometryCoordinate p0 = *(it);
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GeometryCoordinate p1 = *(it + 1);
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if (p0.x < x1 && p1.x < x1) {
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continue;
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} else if (p0.x < x1) {
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p0 = {x1,
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static_cast<int16_t>(
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std::round(p0.y + (p1.y - p0.y) * (static_cast<float>(x1 - p0.x) / (p1.x - p0.x))))};
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} else if (p1.x < x1) {
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p1 = {x1,
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static_cast<int16_t>(
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std::round(p0.y + (p1.y - p0.y) * (static_cast<float>(x1 - p0.x) / (p1.x - p0.x))))};
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}
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if (p0.y < y1 && p1.y < y1) {
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continue;
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} else if (p0.y < y1) {
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p0 = {static_cast<int16_t>(
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std::round(p0.x + (p1.x - p0.x) * (static_cast<float>(y1 - p0.y) / (p1.y - p0.y)))),
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y1};
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} else if (p1.y < y1) {
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p1 = {static_cast<int16_t>(
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std::round(p0.x + (p1.x - p0.x) * (static_cast<float>(y1 - p0.y) / (p1.y - p0.y)))),
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y1};
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}
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if (p0.x >= x2 && p1.x >= x2) {
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continue;
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} else if (p0.x >= x2) {
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p0 = {x2,
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static_cast<int16_t>(
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std::round(p0.y + (p1.y - p0.y) * (static_cast<float>(x2 - p0.x) / (p1.x - p0.x))))};
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} else if (p1.x >= x2) {
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p1 = {x2,
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static_cast<int16_t>(
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std::round(p0.y + (p1.y - p0.y) * (static_cast<float>(x2 - p0.x) / (p1.x - p0.x))))};
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}
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if (p0.y >= y2 && p1.y >= y2) {
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continue;
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} else if (p0.y >= y2) {
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p0 = {static_cast<int16_t>(
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std::round(p0.x + (p1.x - p0.x) * (static_cast<float>(y2 - p0.y) / (p1.y - p0.y)))),
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y2};
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} else if (p1.y >= y2) {
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p1 = {static_cast<int16_t>(
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std::round(p0.x + (p1.x - p0.x) * (static_cast<float>(y2 - p0.y) / (p1.y - p0.y)))),
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y2};
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}
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if (clippedLines.empty() || (!clippedLines.back().empty() && !(p0 == clippedLines.back().back()))) {
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clippedLines.emplace_back();
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clippedLines.back().push_back(p0);
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}
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clippedLines.back().push_back(p1);
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}
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}
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return clippedLines;
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}
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} // end namespace util
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} // end namespace mbgl
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