Problems limiting object rotation with Mathf.Clamp

Question

I am working on a game that rotates an object on the z axis. I need to limit the total rotation to 80 degrees. I tried the following code, but it doesn't work. minAngle = -40.0f and maxAngle = 40.0f

Vector3 pos = transform.position;
pos.z = Mathf.Clamp(pos.z, minAngle, maxAngle);
transform.position = pos;

Answer 1

The code you posted clamps the z position. What you want is to use transform.rotation

void ClampRotation(float minAngle, float maxAngle, float clampAroundAngle = 0)
{
    //clampAroundAngle is the angle you want the clamp to originate from
    //For example a value of 90, with a min=-45 and max=45, will let the angle go 45 degrees away from 90

    //Adjust to make 0 be right side up
    clampAroundAngle += 180;

    //Get the angle of the z axis and rotate it up side down
    float z = transform.rotation.eulerAngles.z - clampAroundAngle;

    z = WrapAngle(z);

    //Move range to [-180, 180]
    z -= 180;

    //Clamp to desired range
    z = Mathf.Clamp(z, minAngle, maxAngle);

    //Move range back to [0, 360]
    z += 180;

    //Set the angle back to the transform and rotate it back to right side up
    transform.rotation = Quaternion.Euler(transform.rotation.eulerAngles.x, transform.rotation.eulerAngles.y, z + clampAroundAngle);
}

//Make sure angle is within 0,360 range
float WrapAngle(float angle)
{
    //If its negative rotate until its positive
    while (angle < 0)
        angle += 360;

    //If its to positive rotate until within range
    return Mathf.Repeat(angle, 360);
}

Answer 2

Here's a static version of the nice solution by Imapler that, instead of changing the angle itself, it returns the campled angle, so it can be used with any axis.

public static float ClampAngle(
    float currentValue,
    float minAngle,
    float maxAngle,
    float clampAroundAngle = 0
) {
    return Mathf.Clamp(
        WrapAngle(currentValue - (clampAroundAngle + 180)) - 180,
        minAngle,
        maxAngle
    ) + 360 + clampAroundAngle;
}

public static float WrapAngle(float angle)
{
    while (angle < 0) {
        angle += 360;
    }
    return Mathf.Repeat(angle, 360);
}

Or if you don't expect to use the WrapAngle method, here's an all-in-one version:

public static float ClampAngle(
    float currentValue,
    float minAngle,
    float maxAngle,
    float clampAroundAngle = 0
) {
    float angle = currentValue - (clampAroundAngle + 180);

    while (angle < 0) {
        angle += 360;
    }

    angle = Mathf.Repeat(angle, 360);

    return Mathf.Clamp(
        angle - 180,
        minAngle,
        maxAngle
    ) + 360 + clampAroundAngle;
}

So now you can do:

transform.localEulerAngles.x = YourMathf.ClampAngle(
    transform.localEulerAngles.x,
    minX,
    maxX
);