koobas.hobune.stream
RectTransform position relative to Its Parent scale
I have a UI Element that can be Zoom In & Out (This feature works by modifying Its sizeDelta) and You can create Pins but when you Zoom In/Out the Pins you've created keep their positions so they not longer represent what you original intended (They are already a child of this UI Element, hence the wording of the question but RectTransform don't work like regular Transforms, please don't answer by saying "Make it a child")
I'm having a hard time solving this as It easy as It may seem. Any help it will be greatly appreciated. I need to do this via code.
Also the Canvas is set to Screen Space - Overlay
Attach this script to your pins (assuming they're children of your UI element):
public class Pin : MonoBehaviour
{
RectTransform parentRect = null;
float posPercentX = 0.0f;
float posPercentY = 0.0f;
void Start()
{
parentRect = transform.parent.GetComponent<RectTransform>();
Vector2 halfRectSize = parentRect.sizeDelta * 0.5f;
posPercentX = Mathf.InverseLerp(-halfRectSize.x, halfRectSize.x, transform.localPosition.x);
posPercentY = Mathf.InverseLerp(-halfRectSize.y, halfRectSize.y, transform.localPosition.y);
}
void Update()
{
Vector2 halfRectSize = parentRect.sizeDelta * 0.5f;
float posX = Mathf.Lerp(-halfRectSize.x, halfRectSize.x, posPercentX);
float posY = Mathf.Lerp(-halfRectSize.y, halfRectSize.y, posPercentY);
transform.localPosition = new Vector2(posX, posY);
}
}
When a pin is first placed (in this case I've put this in the Start method), the code determines where the pin is positioned as a percentage relative to the bounds of the parent rect at its current size. This results in an X and Y coordinate that sits between 0 and 1 (similar to what UV coordinates are for a texture map basically).
In Update, these percentage values are then used to get back the correct X and Y position of the pin by lerping them against the new size of the parent rect.
