message: use subrtraction & rounding to determine equality
diff: */
  export function isPointEqual(a: IPoint, b: IPoint, withinDistance?: number): boolean {
  if (!withinDistance) {
  - return a[0] == b[0] && a[1] == b[1];
  + return round(a[0] - b[0]) == 0 && round(a[1] - b[1]) == 0;
  } else {
  if (!a || !b) return false;
  var distance = measure.pointDistance(a, b);
  