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23 lines
823 B
JavaScript
23 lines
823 B
JavaScript
async function findConvexHull(points) {
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if (!Array.isArray(points) || points.length < 1) return [];
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash-es@4.17.21/lodash.default.min.js');
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const s = _.uniqBy(points, p => `${p.x},${p.y}`);
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if (s.length < 2) return s.slice();
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const pts = _.sortBy(s, ['x', 'y']);
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const c = (o, a, b) => (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
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const l = [];
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for (let p of pts) {
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for (; l.length > 1 && c(l[l.length - 2], l[l.length - 1], p) <= 0;) l.pop();
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l.push(p);
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}
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const u = [];
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for (let i = pts.length - 1; i >= 0; i--) {
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const p = pts[i];
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for (; u.length > 1 && c(u[u.length - 2], u[u.length - 1], p) <= 0;) u.pop();
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u.push(p);
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}
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l.pop();
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u.pop();
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return l.concat(u);
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}
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export default findConvexHull; |