unity3d用鼠标拖动物体的一段代码

这是一段拖动物体的代码，比较简洁明了，对了解unity3d脚本概念有些帮助！在此加上注释分享！
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
    }
}