code: function (evt) {
      var direction;
      var canvas = this.el.sceneEl.canvas;
      var deltaY;
      var yawObject = this.yawObject;
  
      if (!this.touchStarted || !this.data.touchEnabled) { return; }
  
      deltaY = 2 * Math.PI * (evt.touches[0].pageX - this.touchStart.x) / canvas.clientWidth;
  
      direction = this.data.reverseTouchDrag ? 1 : -1;
      // Limit touch orientaion to to yaw (y axis).
      yawObject.rotation.y -= deltaY * 0.5 * direction;
      this.touchStart = {
        x: evt.touches[0].pageX,
        y: evt.touches[0].pageY
      };
    }
docs: Translate touch move to Y-axis rotation.