isEarHashed function

bool isEarHashed(dynamic ear, dynamic minX, dynamic minY, dynamic invSize,)

Implementation

bool isEarHashed(ear, minX, minY, invSize) {
  var a = ear.prev, b = ear, c = ear.next;

  if (area(a, b, c) >= 0) return false; // reflex, can't be an ear

  // triangle bbox; min & max are calculated like this for speed
  var minTX = a.x < b.x ? (a.x < c.x ? a.x : c.x) : (b.x < c.x ? b.x : c.x),
      minTY = a.y < b.y ? (a.y < c.y ? a.y : c.y) : (b.y < c.y ? b.y : c.y),
      maxTX = a.x > b.x ? (a.x > c.x ? a.x : c.x) : (b.x > c.x ? b.x : c.x),
      maxTY = a.y > b.y ? (a.y > c.y ? a.y : c.y) : (b.y > c.y ? b.y : c.y);

  // z-order range for the current triangle bbox;
  var minZ = zOrder(minTX, minTY, minX, minY, invSize),
      maxZ = zOrder(maxTX, maxTY, minX, minY, invSize);

  var p = ear.prevZ, n = ear.nextZ;

  // look for points inside the triangle in both directions
  while (p != null && p.z >= minZ && n != null && n.z <= maxZ) {
    if (p != ear.prev &&
        p != ear.next &&
        pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
        area(p.prev, p, p.next) >= 0) return false;
    p = p.prevZ;

    if (n != ear.prev &&
        n != ear.next &&
        pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
        area(n.prev, n, n.next) >= 0) return false;
    n = n.nextZ;
  }

  // look for remaining points in decreasing z-order
  while (p != null && p.z >= minZ) {
    if (p != ear.prev &&
        p != ear.next &&
        pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, p.x, p.y) &&
        area(p.prev, p, p.next) >= 0) return false;
    p = p.prevZ;
  }

  // look for remaining points in increasing z-order
  while (n != null && n.z <= maxZ) {
    if (n != ear.prev &&
        n != ear.next &&
        pointInTriangle(a.x, a.y, b.x, b.y, c.x, c.y, n.x, n.y) &&
        area(n.prev, n, n.next) >= 0) return false;
    n = n.nextZ;
  }

  return true;
}