unity Input.GetAxis和Input.GetAxisRaw
float h = Input.GetAxis("Horizontal") ;//h range from -1 to 1
float v = Input.GetAxis("Vertical") ;//v range from -1 to 1
float h = Input.GetAxisRaw("Horizontal") ;//h is -1, 0, or 1
float v = Input.GetAxisRaw("Vertical") ;//v is -1, 0, or 1