mirror of
https://github.com/lynchmarkHQ/lynchmark.com.git
synced 2026-10-19 10:14:51 +00:00
24 lines
643 B
JavaScript
24 lines
643 B
JavaScript
const findConvexHull = async (pts) => {
|
|
const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash@4.17.21/+esm')
|
|
const s = _.sortBy(_.uniqWith(pts, _.isEqual), ['x', 'y'])
|
|
if (s.length < 3) return s
|
|
|
|
const cross = (a, b, o) => (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x)
|
|
const build = (list) => {
|
|
const h = []
|
|
for (const p of list) {
|
|
while (h.length >= 2 && cross(h[h.length - 1], p, h[h.length - 2]) <= 0) h.pop()
|
|
h.push(p)
|
|
}
|
|
return h
|
|
}
|
|
|
|
const l = build(s)
|
|
const u = build([...s].reverse())
|
|
|
|
l.pop()
|
|
u.pop()
|
|
|
|
return [...l, ...u]
|
|
}
|
|
export default findConvexHull; |