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19 lines
668 B
JavaScript
19 lines
668 B
JavaScript
async function findConvexHull(points) {
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const { uniqWith, isEqual, sortBy } = await import('https://cdn.jsdelivr.net/npm/lodash-es@4.17.21/lodash.js')
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const pts = sortBy(uniqWith(points, isEqual), ['x', 'y'])
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if (pts.length < 3) return pts
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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 scan = (src, acc = []) => {
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src.forEach(p => {
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while (acc.length > 1 && cross(acc.at(-2), acc.at(-1), p) <= 0) acc.pop()
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acc.push(p)
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})
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return acc
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}
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const lower = scan(pts)
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const upper = scan([...pts].reverse())
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lower.pop()
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upper.pop()
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return lower.concat(upper)
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}
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export default findConvexHull; |