How to ease toward a rotation limit, instead of stopping abruptly?

Question

I rotate my camera using a framerate-independent exponential ease-out blend like so:

    _x += Input.GetAxis("Mouse X") * xSpeed;
    float target = 0f; //I want to blend towards 0
    float sharpness = 0.05f; //the smaller this value, the longer it takes to settle down to the target value
    float referenceFramerate = 90f;//the approximate framerate on my developer machine
    float blend = 1f - Mathf.Pow(1f - sharpness, Time.deltaTime * referenceFramerate);
    _x = Mathf.Lerp(_x, target, blend);

This works fine.

Now my camera should be clipped at a certain rotation yaw.

The new camera rotation yaw is calculated like this:

    _CurrentYaw += _x * Mathf.Abs(_CameraDefaultPos.z);
    if (_CurrentYaw > 160f)
    {
       _CurrentYaw = 160f;
    }
    else if (_CurrentYaw < -120f)
    {
       _CurrentYaw = -120f;
    }

This clipping part of my code makes the camera stop abruptly at the maximum.

How could the above Mathf.Lerp function be adopted to make it so that the _x value would be damped more quickly when going towards the rotation limit?

Answer 1

Here's one way you can tackle it: computing how far you are from the center of the allowed range, and applying a braking multiplier the closer you are to the edge.

public class LimitedCameraYaw : MonoBehaviour
{
    const float referenceFramerate = 30.0f;

    public float yawCenter = 20;
    public float yawRange = 140;

    public float yawInputFalloff = 0.01f;
    public float yawSpeed = 60.0f;

    float _currentYaw;
    float _yawRate;

    void Update() {
        // Fade old input before capturing new, so we don't dull the freshest data.
        float blend = Mathf.Pow(1.0f - yawInputFalloff, referenceFramerate * Time.deltaTime);
        // A Lerp toward zero is just the same as a multiplication by the complement of the blend factor.    
        _yawRate *= blend;

        // Accelerate by mouse movement over the past frame.
        // (May need adjustment for display resolution).
        _yawRate += Input.GetAxis("Mouse X");

        float yawDelta = yawSpeed * _yawRate * Time.deltaTime;

        float offCenter = _currentYaw - yawCenter;

        // If we're moving away from the center, slow down as we approach the edge.
        if (yawDelta * offCenter > 0) {
            float extremity = offCenter / yawRange;
            yawDelta *= 1.0f - extremity * extremity;
        }

        // Ensure we never overshoot the allowed range.
        _currentYaw = Mathf.Clamp(_currentYaw + yawDelta,
                                  yawCenter - yawRange,
                                  yawCenter + yawRange);

        transform.eulerAngles = Vector3.up * _currentYaw;
    }
}