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17 lines
720 B
JavaScript
17 lines
720 B
JavaScript
const findConvexHull = async (points) => {
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash@4.17.21/+esm');
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const pts = _.sortBy(_.uniqWith(points, _.isEqual), ['x', 'y']);
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if (pts.length < 3) return pts;
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const cross = (o, a, b) => (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
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const chain = (list) => {
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const h = [];
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for (const p of list) {
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while (h.length >= 2 && cross(h[h.length - 2], h[h.length - 1], p) <= 0) h.pop();
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h.push(p);
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}
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return h;
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};
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const lower = chain(pts), upper = chain([...pts].reverse());
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return [...lower.slice(0, -1), ...upper.slice(0, -1)];
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};
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export default findConvexHull; |