Lerp to target position, but only within a radius - unity3d

Question

I am making a 3D game but my player can only move on the X and Y axis. I have a player with an attached camera following my mouse, but I only want it to follow up to a max radius distance from Vector3.zero, even if my mouse is beyond those bounds.
I have tried repositioning the player to the max distance on radius every frame it tries to follow the mouse outside its bounds, but this causes camera jitters even in LateUpdate.
void LateUpdate()
{
if (Input.GetMouseButtonDown(0)) {
firstTouchPos = movementCam.ScreenPointToRay(Input.mousePosition);
playerPos = transform.position;
}
if (Input.GetMouseButton(0)) {
Ray currentTouchPos = movementCam.ScreenPointToRay(Input.mousePosition);
Vector2 direction = currentTouchPos.origin - firstTouchPos.origin;
float distance = Vector3.Distance(transform.position, Vector3.zero);
if (distance >= radius) {
targetPosition = direction.normalized * radius;
} else {
targetPosition = playerPos + direction * touchSensitivity;
}
}
transform.position = Vector3.Lerp(transform.position, targetPosition, Time.deltaTime * followSpeed);
}
I'm thinking there must be a way to clamp the positioning of the player to a radius so that I don't have to "leash" him back by repositioning him through code every frame.

Answer 1

You should try using Vector3.ClampMagnitude().

Answer 2

The solution was to use Clamp Magnitude.
void LateUpdate()
{
if (Input.GetMouseButtonDown(0)) {
firstTouchPos = movementCam.ScreenPointToRay(Input.mousePosition);
playerPos = transform.position;
}
if (Input.GetMouseButton(0)) {
// targetPosition will follow finger movements
Ray currentTouchPos = movementCam.ScreenPointToRay(Input.mousePosition);
Vector2 direction = currentTouchPos.origin - firstTouchPos.origin;
targetPosition = playerPos + direction * touchSensitivity;
}
transform.position = Vector3.Lerp(transform.position, targetPosition, Time.deltaTime * followSpeed);
transform.position = Vector3.ClampMagnitude(transform.position, radius);
}