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23 lines
646 B
JavaScript
23 lines
646 B
JavaScript
export const findConvexHull = async (pts) => {
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash@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 cross = (a, b, c) => (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.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 l = chain(S)
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const u = chain([...S].reverse())
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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; |