Sweep Line (Plane Sweep)

A vertical line sweeps left→right; events drive a status structure; intersections are detected when neighbors meet.

segment active (in status) being tested intersection sweep line

Sweep x: — | Events: 0 | Active: 0 | Intersections (k): 0 | Neighbor tests: 0

Slow Fast

Custom segments (x1,y1,x2,y2 per line)

Press Run to start the sweep, or Step to advance one event at a time. The orange vertical line is the sweep line; it stops only at events.

Operation	Cost
Sort all events	O(n log n)
Status insert / delete / neighbor	O(log n)
Event-queue extract-min / insert	O(log n)
Bentley–Ottmann (report all)	O((n + k) log n)
Naive all-pairs baseline	O(n²)