Unity script (C#) to restrict camera rotation on the y-axis

Question

I used Unity to create a simple first-person game, where you use the WASD-keys to move around and the mouse to look around. At the moment the camera rotation on the x- and y-axis is not restricted (if you look up you can turn a complete 360° on the y-axis). Now I want to cap this, so you can not go further than looking straight up. My scrip so far (no restrictions yet):

public float rotationY = 0;
public float viewRange = 90.0;

void Update () {

    float rotationX = Input.GetAxis ("Mouse X") * mouseSensitivity;
    transform.Rotate (0, rotationX, 0);

    rotationY = Input.GetAxis ("Mouse Y") * mouseSensitivity;
    rotationY = Mathf.Clamp (rotationY, -viewRange, viewRange);
    Camera.main.transform.Rotate (-rotationY, 0, 0);
                }

Now i tried to limit the y-axis camera movement by replacing the last line by

Camera.main.transform.localRotation = Quaternion.Euler (rotationY,0,0);

But unfortunately this results in not being able to rotate the camera in y-direction at all.

Answer 1

You have to subtract the "Mouse Y" axis rotation on each update, so just replace this:

rotationY = Input.GetAxis ("Mouse Y") * mouseSensitivity;

...with this:

rotationY -= Input.GetAxis ("Mouse Y") * mouseSensitivity;

It's also important that you don't use Camera.main.transform.Rotate, but uses localRotation instead (as you point out yourself).

Answer 2

The problem is that Transform.Rotate applies rotation (not sets the angle as you can expect). So your clamp has no effect. What you want to clamp is Transform.localEulerAngles