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18 lines
590 B
JavaScript
18 lines
590 B
JavaScript
const findConvexHull = async (pts) => {
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash-es@4.17.21/+esm')
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const s = _.sortBy(_.uniqWith(pts, _.isEqual), ['x', 'y'])
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if (s.length < 3) return s
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const k = (a, b, c) => (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x)
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const f = (h, p) => {
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while (h.length >= 2 && k(h[h.length - 2], h[h.length - 1], p) <= 0) h.pop()
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h.push(p)
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return h
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}
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const l = _.reduce(s, f, [])
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const u = _.reduceRight(s, f, [])
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return [..._.dropRight(l), ..._.dropRight(u)]
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}
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export default findConvexHull; |