c# - Check if UI elements/RectTransform are overlapping

Question

I'd like to know how I check whether two UI Panels on my Unity Canvas are overlapping each other.

Currently I am doing this by comparing the canvas elements Rects

Canvas Settings

• Render Mode: Screen Space - Camera
• Pixel Perfect: [Yes]
• Render Camera: Main Camera
• Plane Distance: 100
• Sorting Layer: Default
• Order In Layer: 0

Canvas Scaler Settings

• UI Scale Mode: Constant Pixel Size
• Scale Factor: 1
• Reference Pixels Per Unit: 100

Code I am using to check

[Header("Check For Overlap")]
public RectTransform PlayerBar;
public RectTransform LeftBar;
public Rect RectOne;
public Rect RectTwo;
public bool overlapping;

//Check if the two canvas element Rects overlap each other

public void CheckForOverlap()
{
    overlapping = false;
    // Convert Canvas RectTransforms to World Rects
    RectOne = GetWorldRect(LeftBar);
    RectTwo = GetWorldRect(PlayerBar);

    if (RectOne.Overlaps(RectTwo))
    {
        overlapping = true;
    }
}


public Rect GetWorldRect(RectTransform rt)
{
    //  Get World corners, take top left
    Vector3[] corners = new Vector3[4];
    rt.GetWorldCorners(corners);
    Vector3 topLeft = corners[0];

    // Rect Size ... I'm not sure if this is working correctly?
    Vector2 size = new Vector2(rt.rect.size.x, rt.rect.size.y);
    return new Rect(topLeft, size);
}

What happens

'Overlapping' bool instantly changes to true.

The Rect One returns as (example)

X -7.5, Y 2.5 W 98.5, H 164.1667

Answer 1

Updated version considering scale of the rectTransform.

public static class RectTransformExtensions
{

    public static bool Overlaps(this RectTransform a, RectTransform b) {
        return a.WorldRect().Overlaps(b.WorldRect());
    }
    public static bool Overlaps(this RectTransform a, RectTransform b, bool allowInverse) {
        return a.WorldRect().Overlaps(b.WorldRect(), allowInverse);
    }

    public static Rect WorldRect(this RectTransform rectTransform) {
        Vector2 sizeDelta = rectTransform.sizeDelta;
        float rectTransformWidth = sizeDelta.x * rectTransform.lossyScale.x;
        float rectTransformHeight = sizeDelta.y * rectTransform.lossyScale.y;

        Vector3 position = rectTransform.position;
        return new Rect(position.x - rectTransformWidth / 2f, position.y - rectTransformHeight / 2f, rectTransformWidth, rectTransformHeight);
    }
}