Function computeIntervalInputData

docs/tests/v2/es6/js/sanddance.js:51950–51979

* velocity is calculated every x ms * @param {Object} session * @param {Object} input

(session, input)

  function computeIntervalInputData(session, input) {
    var last = session.lastInterval || input,
        deltaTime = input.timeStamp - last.timeStamp,
        velocity,
        velocityX,
        velocityY,
        direction;

    if (input.eventType != INPUT_CANCEL && (deltaTime > COMPUTE_INTERVAL || last.velocity === undefined)) {
      var deltaX = input.deltaX - last.deltaX;
      var deltaY = input.deltaY - last.deltaY;
      var v = getVelocity(deltaTime, deltaX, deltaY);
      velocityX = v.x;
      velocityY = v.y;
      velocity = abs(v.x) > abs(v.y) ? v.x : v.y;
      direction = getDirection(deltaX, deltaY);
      session.lastInterval = input;
    } else {
      // use latest velocity info if it doesn't overtake a minimum period
      velocity = last.velocity;
      velocityX = last.velocityX;
      velocityY = last.velocityY;
      direction = last.direction;
    }

    input.velocity = velocity;
    input.velocityX = velocityX;
    input.velocityY = velocityY;
    input.direction = direction;
  }
  /**
   * create a simple clone from the input used for storage of firstInput and firstMultiple
   * @param {Object} input