Restrict Direction of rotation in Realtime - unity3d

Question

have a hand of clock which the player once starts rotating (Dragging) CCW until he completes one full rotation. ( Without lifting drag )
I am trying to lock the rotation to only CCW direction while/once the player starts rotating. I got help from the following links : [Detect Direction][1] by #BobBobson108
Here is gif of what is actually happening: Demo
void OnMouseDrag()
{
//rotation
Vector3 mousePos = Input.mousePosition;
mousePos.z = 5.23f;
Vector3 objectPos = Camera.main.WorldToScreenPoint(transform.position);
mousePos.x = mousePos.x - objectPos.x;
mousePos.y = mousePos.y - objectPos.y;
angle = Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg;
transform.rotation = Quaternion.Euler(new Vector3(0, 0, angle - 90f));
hand_vector = transform.up;
cross_product = Vector3.Cross(ref_vector, hand_vector);
dot_product = Vector3.Dot(cross_product, transform.forward*-1);
//Debug.Log("Hand Vector: " + hand_vector);
//Debug.Log("Ref Vector: " + ref_vector);
Debug.Log(cross_product);
Debug.Log(dot_product);
}
I tried to debug the values of the cross product, but the direction of resultant vector seems to be same even when when the player starts backward rotation.
Also the cross product vector changes direction only when the player starts rotation in CW direction from the default position i.e. 12 'o clock.
I have very less experience of working with Quaternions and rotations. Any help will be highly helpful. Thanks !!!
Desired

Answer 1

Use http://docs.unity3d.com/ScriptReference/Vector3.Angle.html function to get the value of the angle. You should get a positive/negative value depending on the direction.
You could then lock the rotation if the sign is not the correct direction you want.

Answer 2

I managed to figure out a solution to above question. Here I am posting my solution in case anyone stumbles across a similar situation in future.
void OnMouseDrag()
{
transform.Rotate(new Vector3(0,0, Mathf.Sqrt(Input.GetAxis("Mouse X") * Input.GetAxis("Mouse X") + Input.GetAxis("Mouse Y") * Input.GetAxis("Mouse Y"))));
/*
Vector3 mousePos = Input.mousePosition;
mousePos.z = 5.23f;
Vector3 objectPos = Camera.main.WorldToScreenPoint(transform.position);
mousePos.x = mousePos.x - objectPos.x;
mousePos.y = mousePos.y - objectPos.y;
print("Angle is :");
print(Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg - 90f);
if (counter_clockwise)
{
if (Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg - 90f > 0)
{
angle = Mathf.Max(angle, Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg - 90);
transform.rotation = Quaternion.Euler(new Vector3(0, 0, angle));
}
if (Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg - 90f < 0)
{
angle = Mathf.Max(angle, 360 + (Mathf.Atan2(mousePos.y, mousePos.x) * Mathf.Rad2Deg - 90));
transform.rotation = Quaternion.Euler(new Vector3(0, 0, angle));
}
}
*/
glow_color.a = 1f;
child_yellowglow.color = glow_color;
}
I am setting the direction bools from using this :
void OnMouseDown()
{
Vector3 mouseDragStartPos = Input.mousePosition;
print("Mouse pos: " + mouseDragStartPos);
print(" ref_vector" + ref_vector);
if (mouseDragStartPos.x < ref_vector.x)
{
clockwise = false;
counter_clockwise = true;
print("Left !!!");
}
if (mouseDragStartPos.x >= ref_vector.x)
{
clockwise = true;
counter_clockwise = false;
print("Right !!!");
}
}
Hope this helps !!!