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19 lines
633 B
JavaScript
19 lines
633 B
JavaScript
async function findConvexHull(pts){
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const _=(await import('https://esm.run/lodash@4.17.21')).default;
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let p=_.uniqBy(_.sortBy(pts,['x','y']),q=>[q.x,q.y]);
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if(p.length<=2)return p;
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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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let lower=[];
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for(let q of p){
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while(lower.length>=2&&cross(lower[lower.length-2],lower[lower.length-1],q)<=0)lower.pop();
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lower.push(q);
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}
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let upper=[];
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let rp=[...p].reverse();
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for(let q of rp){
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while(upper.length>=2&&cross(upper[upper.length-2],upper[upper.length-1],q)<=0)upper.pop();
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upper.push(q);
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}
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return lower.slice(0,-1).concat(upper.slice(0,-1));
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}
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export default findConvexHull; |