Raycast rotate help need in unity - unity3d

Question

I have this code which lets an object rotate on Y axis. But I want to rotate the object on Z axis only. I tried to change the hPlane value, but no luck.
How can I do this?
Thanks
private Ray ray;
private Quaternion target;
private float speed = 1000.0f;
// Update is called once per frame
void Update () {
if (Input.GetMouseButton (0)) {
ray = Camera.main.ScreenPointToRay (Input.mousePosition);
Plane hPlane = new Plane(Vector3.up, Vector3.zero);
float distance = 0;
if(hPlane.Raycast(ray, out distance)){
Vector3 targetPoint = ray.GetPoint(distance);
targetPoint += transform.position;
Quaternion targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
float step = speed * Time.deltaTime;
transform.rotation = Quaternion.RotateTowards(transform.rotation, targetRotation,step);
}
}
}
Update:
My Goal is to rotate a bar (cube mesh) on Z axis smoothly using mouse click . The rotation will occur only when (this part I could not do) the mouse touch the corners of the bar.
I have already done the Z axis rotation with this code but the rotation very low (even for speed =1000.0f) and it rotates clockwise I suppose. But I want to move the bar in both direction and the movement will be smooth and faster like Quaternion.RotateTowards
Thanks
private Ray ray;
private RaycastHit hit;
private Quaternion target;
private float speed = 1000.0f;
// Update is called once per frame
void Update () {
if (Input.GetMouseButton (0)) {
ray = Camera.main.ScreenPointToRay (Input.mousePosition);
if(Physics.Raycast(ray, out hit)){
//transform.position = new Vector3(hit.point.x, hit.point.y, 0);
target = Quaternion.Euler(0.0f,0.0f, hit.point.z * speed);
transform.rotation = Quaternion.Slerp(transform.rotation, target, Time.deltaTime);
}
}
}
http://i.stack.imgur.com/7qIcs.jpg

Answer 1

I suggest you to change the orientation of the object axis. For a better use of the Quaternion functions, edit your bar in order to have local Y has rotation axis and local Z as look direction.
Then use this code :
if (Input.GetMouseButton(0))
{
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
if (Physics.Raycast(ray, out hit))
{
Vector3 distance = hit.point - transform.position;
distance.y = 0;
Quaternion targetRotation = Quaternion.LookRotation(distance);
transform.rotation = Quaternion.RotateTowards(transform.rotation, targetRotation, Time.deltaTime * speed);
}
}
Your bar will only rotate around Y axis.