public void OnPointerDown(PointerEventData eventData)
{
List <PointerEventData> pointers = eventData.IsTouchInput() ? touchPointers : mousePointers;
for (int i = 0; i < pointers.Count; i++)
{
if (pointers[i].pointerId == eventData.pointerId)
{
pointers[i] = eventData;
return;
}
}
pointers.Add(eventData);
}