单例 + 摄像头转换

public class SingleTon : MonoBehaviour {

private static SingleTon instance;
private SingleTon() { }
public static SingleTon Instance
{
    get
    {
        if (instance == null)
        {
            instance = new SingleTon();
        }
        return instance;
    }
}






//将屏幕坐标转为世界坐标系的方法
//screenPos：屏幕上的某一点的位置
//targetTrans：3D世界坐标系中的某一个参考位置
public Vector3 MyScreenPointToWorldPoint(Vector3 screenPos,
    Transform targetTrans)
{
    //将3D世界坐标系中的参考物体的z取出，设置给屏幕坐标系
    Vector3 screenV = Camera.main.WorldToScreenPoint(targetTrans.position);

    screenPos.z = screenV.z;
    Vector3 worldPos = Camera.main.ScreenToWorldPoint(screenPos);
    return worldPos;
}