onPointerDown method
      
void
onPointerDown(
    
    
- dynamic event
Implementation
void onPointerDown(event) {
  if (scope.enabled == false) return;
  if (pointers.isEmpty) {
    //scope.domElement.setPointerCapture(event.pointerId);
    scope.domElement.addEventListener(PeripheralType.pointermove, onPointerMove);
    scope.domElement.addEventListener(PeripheralType.pointerup, onPointerUp);
  }
  addPointer(event);
  if (event.pointerType == 'touch') {
    onTouchStart(event);
  } else {
    onMouseDown(event);
  }
}