Function monotoneTriangulate

stackgl_modules/index.js:8572–8627

(points, edges)

function monotoneTriangulate(points, edges) {

  var numPoints = points.length
  var numEdges = edges.length

  var events = []

  //Create point events
  for(var i=0; i<numPoints; ++i) {
    events.push(new Event(
      points[i],
      null,
      EVENT_POINT,
      i))
  }

  //Create edge events
  for(var i=0; i<numEdges; ++i) {
    var e = edges[i]
    var a = points[e[0]]
    var b = points[e[1]]
    if(a[0] < b[0]) {
      events.push(
        new Event(a, b, EVENT_START, i),
        new Event(b, a, EVENT_END, i))
    } else if(a[0] > b[0]) {
      events.push(
        new Event(b, a, EVENT_START, i),
        new Event(a, b, EVENT_END, i))
    }
  }

  //Sort events
  events.sort(compareEvent)

  //Initialize hull
  var minX = events[0].a[0] - (1 + Math.abs(events[0].a[0])) * Math.pow(2, -52)
  var hull = [ new PartialHull([minX, 1], [minX, 0], -1, [], [], [], []) ]

  //Process events in order
  var cells = []
  for(var i=0, numEvents=events.length; i<numEvents; ++i) {
    var event = events[i]
    var type = event.type
    if(type === EVENT_POINT) {
      addPoint(cells, hull, points, event.a, event.idx)
    } else if(type === EVENT_START) {
      splitHulls(hull, points, event)
    } else {
      mergeHulls(hull, points, event)
    }
  }

  //Return triangulation
  return cells
}