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24 lines
754 B
JavaScript
24 lines
754 B
JavaScript
async function findConvexHull(points) {
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash@4/esm/lodash.js');
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if (!points || points.length < 3) return [...(points || [])];
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const pts = _.sortBy(_.uniqWith(points, (a, b) => a.x === b.x && a.y === b.y), ['x', 'y']);
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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 build = arr => {
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const h = [];
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for (const p of arr) {
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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 = build(pts);
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const upper = build([...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; |