鼠标拖动物体

var mouseOverColor = Color.blue;//声明变量为蓝色
private var originalColor : Color;//声明变量存储本来颜色
function Start ()
{
 originalColor = renderer.sharedMaterial.color;//开始时得到物体本来着色
}
function OnMouseEnter ()
{
 renderer.material.color = mouseOverColor;//当鼠标滑过时改变物体颜色为蓝色
}

function OnMouseExit ()
{
 renderer.material.color = originalColor;//当鼠标滑出时恢复物体本来颜色
}

function OnMouseDown ()
{
 var screenSpace = Camera.main.WorldToScreenPoint(transform.position);//三维物体坐标转屏幕坐标
 //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
 var offset = transform.position - Camera.main.ScreenToWorldPoint(Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z));
 print("down");
 while (Input.GetMouseButton(0))
 {
  //print("button0");
  var curScreenSpace = Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z);
  var curPosition = Camera.main.ScreenToWorldPoint(curScreenSpace) + offset;
  transform.position = curPosition;
  yield;//这个很重要，循环执行
 }
}