Unity物体移动

float horizontal = Input.GetAxis("Horizontal");
float vertical = Input.GetAxis("Vertical");
Vector3 movement = new Vector3(vertical,horizontal,0f);
GetComponent<Rigidbody>().velocity = speed * movement;
GetComponent<Rigidbody>().positon = new Vector3(
Mathf.Clamp(GetComponent<Rigidbody>().positon.x,xmin,xmax),
Mathf.Clamp(GetComponent<Rigidbody>().positon,y,ymin,ymax),
GetComponent<Rigidbody>().positon.z);