I am using the basic FPS Camera Mouse script, that came with Unity. Is there something I can add to this script that I can make the view look around only when the Mouse Button is held down and the mouse is moved. Right now the camera moves around all the time when the mouse is moves. Thanks.

[AddComponentMenu("Camera-Control/Mouse Look")] public class MouseLook : MonoBehaviour {

public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
public RotationAxes axes = RotationAxes.MouseXAndY;
public float sensitivityX = 15F;
public float sensitivityY = 15F;

public float minimumX = -360F;
public float maximumX = 360F;

public float minimumY = -60F;
public float maximumY = 60F;

float rotationX = 0F;
float rotationY = 0F;

Quaternion originalRotation;

void Update ()
{
    if (axes == RotationAxes.MouseXAndY)
    {
        // Read the mouse input axis
        rotationX += Input.GetAxis("Mouse X") * sensitivityX;
        rotationY += Input.GetAxis("Mouse Y") * sensitivityY;

        rotationX = ClampAngle (rotationX, minimumX, maximumX);
        rotationY = ClampAngle (rotationY, minimumY, maximumY);

        Quaternion xQuaternion = Quaternion.AngleAxis (rotationX, Vector3.up);
        Quaternion yQuaternion = Quaternion.AngleAxis (rotationY, Vector3.left);

        transform.localRotation = originalRotation * xQuaternion * yQuaternion;
    }
    else if (axes == RotationAxes.MouseX)
    {
        rotationX += Input.GetAxis("Mouse X") * sensitivityX;
        rotationX = ClampAngle (rotationX, minimumX, maximumX);

        Quaternion xQuaternion = Quaternion.AngleAxis (rotationX, Vector3.up);
        transform.localRotation = originalRotation * xQuaternion;
    }
    else
    {
        rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
        rotationY = ClampAngle (rotationY, minimumY, maximumY);

        Quaternion yQuaternion = Quaternion.AngleAxis (rotationY, Vector3.left);
        transform.localRotation = originalRotation * yQuaternion;
    }
}

void Start ()
{
    // Make the rigid body not change rotation
    if (rigidbody)
        rigidbody.freezeRotation = true;
    originalRotation = transform.localRotation;
}

public static float ClampAngle (float angle, float min, float max)
{
    if (angle < -360F)
        angle += 360F;
    if (angle > 360F)
        angle -= 360F;
    return Mathf.Clamp (angle, min, max);
}

}