IEnumerator OnMouseDown()
{
//将物体由世界坐标系转换为屏幕坐标系
Vector3 screenSpace = Camera.main.WorldToScreenPoint(transform.position);//三维物体坐标转屏幕坐标
//完成两个步骤 1.由于鼠标的坐标系是2维，需要转换成3维的世界坐标系
// 2.只有3维坐标情况下才能来计算鼠标位置与物理的距离，offset即是距离
//将鼠标屏幕坐标转为三维坐标，再算出物体位置与鼠标之间的距离
Vector3 offset = transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z));
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition) /*new Ray(Camera.main.transform.position, transform.forward)*/;
RaycastHit hit;
if (Physics.Raycast(ray, out hit, Mathf.Infinity))
{
GetBoderInfo(hit.point, hit.transform.position, out borderPoint);
Debug.Log(borderPoint);
}
while (Input.GetMouseButton(0))
{
//得到现在鼠标的2维坐标系位置
Vector3 curScreenSpace = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z);
//将当前鼠标的2维位置转换成3维位置，再加上鼠标的移动量
Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenSpace) + offset;
if (borderPoint.Equals(Pivot.Center) || borderPoint.Equals(Pivot.Empty))
{
//curPosition就是物体应该的移动向量赋给transform的position属性
transform.position = curPosition;
}
else
{
DragBorder(curPosition);
}
yield return(new WaitForFixedUpdate()); //这个很重要，循环执行
}
}