Function getDirection

docs/tests/v2/es6/js/sanddance.js:52064–52074

* get the direction between two points * @param {Number} x * @param {Number} y * @return {Number} direction

(x, y)

  function getDirection(x, y) {
    if (x === y) {
      return DIRECTION_NONE;
    }

    if (abs(x) >= abs(y)) {
      return x < 0 ? DIRECTION_LEFT : DIRECTION_RIGHT;
    }

    return y < 0 ? DIRECTION_UP : DIRECTION_DOWN;
  }
  /**
   * calculate the absolute distance between two points
   * @param {Object} p1 {x, y}