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23 lines
685 B
JavaScript
23 lines
685 B
JavaScript
const findConvexHull = async (rawPoints) => {
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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(rawPoints, _.isEqual), ['x', 'y'])
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if (pts.length < 3) return pts
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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 build = (list) => {
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const h = []
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list.forEach(p => {
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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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lower.pop(), upper.pop()
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return [...lower, ...upper]
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}
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export default findConvexHull; |