Circular Slider for Rotation in Unity - unity3d

Question

For this setup in Unity, there is a circular dial. The values of the rotation are being used to scale the model. The actual scaling code is removed because there is a bug in the way zAngle value is calculated. Ideally it should be in steady increments in all directions, but here, the values jump across horizontal and vertical axes but they grow slowly when the dial is dragged in other directions.
Is there a recommended practice for such cases when using the screen drag position to calculate the rotation value?
zAngle is the final angle value used to rotate the dial and would be also used after some clamping to scale the model, but that is not the requirement here.
public class CircularScaleDial : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
{
RectTransform rectTransform;
public GameObject model;
[SerializeField] Vector2 delta = Vector2.one;
[SerializeField] CanvasScaler canvasScaler;
private Vector3 startPosition;
[SerializeField] int zAngle;
Vector3 gd1 = Vector3.zero;
private void Awake()
{
rectTransform = GetComponent<RectTransform>();
}
public void OnBeginDrag(PointerEventData eventData)
{
startPosition = GetDelta_3(eventData);
}
int GetAngleFromPosition(Vector2 pos) {
var angleRadians = Mathf.Atan2(pos.y, pos.x);
var angleDegrees = angleRadians * Mathf.Rad2Deg;
return (int)angleDegrees;
}
Vector3 GetDelta_3(PointerEventData data)
{
Vector3 pos = new Vector3(data.position.x, data.position.y, 0);
Vector3 s2vp = Camera.main.ScreenToViewportPoint(pos);
return s2vp;
}
public void OnDrag(PointerEventData data)
{
if (data.dragging)
{
gd1 = GetDelta_3(data);
delta.x = gd1.x;
delta.y = gd1.y;
zAngle = GetAngleFromPosition(delta);
rectTransform.localRotation = Quaternion.Euler(new Vector3(0, 0, zAngle));
}
}
}

Answer 1

It was sort of fixed with a simpler code. Made other tweaks but this was the main change. The essence here is to resolve the delta along y. For this case I just take the y component but ideally we would take a dot product of two values to resolve one along the other.
public void OnBeginDrag(PointerEventData eventData)
{
startV2 = eventData.position;
}
public void OnDrag(PointerEventData data)
{
if (data.dragging)
{
endV2 = data.position;
Vector2 deltaV2 = endV2 - startV2;
deltaV2 = deltaV2.normalized;
rectTransform.Rotate(new Vector3(0, 0, -deltaV2.y), Space.Self);
startV2 = endV2;
}
}