jsts
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A JavaScript library of spatial predicates and functions for processing geometry
50 lines (47 loc) • 1.47 kB
JavaScript
import SweepLineEvent from './SweepLineEvent.js'
import Collections from '../../../../../java/util/Collections.js'
import ArrayList from '../../../../../java/util/ArrayList.js'
export default class SweepLineIndex {
constructor() {
SweepLineIndex.constructor_.apply(this, arguments)
}
static constructor_() {
this.events = new ArrayList()
this._indexBuilt = null
this._nOverlaps = null
}
add(sweepInt) {
const insertEvent = new SweepLineEvent(sweepInt.getMin(), null, sweepInt)
this.events.add(insertEvent)
this.events.add(new SweepLineEvent(sweepInt.getMax(), insertEvent, sweepInt))
}
computeOverlaps(action) {
this._nOverlaps = 0
this.buildIndex()
for (let i = 0; i < this.events.size(); i++) {
const ev = this.events.get(i)
if (ev.isInsert())
this.processOverlaps(i, ev.getDeleteEventIndex(), ev.getInterval(), action)
}
}
processOverlaps(start, end, s0, action) {
for (let i = start; i < end; i++) {
const ev = this.events.get(i)
if (ev.isInsert()) {
const s1 = ev.getInterval()
action.overlap(s0, s1)
this._nOverlaps++
}
}
}
buildIndex() {
if (this._indexBuilt) return null
Collections.sort(this.events)
for (let i = 0; i < this.events.size(); i++) {
const ev = this.events.get(i)
if (ev.isDelete())
ev.getInsertEvent().setDeleteEventIndex(i)
}
this._indexBuilt = true
}
}