Convert RectTransform.rect to Rect world

Questions & Answers
1

I want to turn a RectTransform.rect into a world space Rect object. RectTransform doesn’t appear to have a method to convert the rectangle object to world coordinates. But I want something like the following.

myRectTransform.ConvertToWorldRect();

2

Looks like you can chain together a few Unity API methods for some clever conversion. Example below includes support for modifying the Rect’s size based upon the current Canvas scale.

using UnityEngine;
using System.Collections;

static public class RectTransformExt {
	/// <summary>
	/// Converts RectTransform.rect's local coordinates to world space
	/// Usage example RectTransformExt.GetWorldRect(myRect, Vector2.one);
	/// </summary>
	/// <returns>The world rect.</returns>
	/// <param name="rt">RectangleTransform we want to convert to world coordinates.</param>
	/// <param name="scale">Optional scale pulled from the CanvasScaler. Default to using Vector2.one.</param>
	static public Rect GetWorldRect (RectTransform rt, Vector2 scale) {
		// Convert the rectangle to world corners and grab the top left
		Vector3[] corners = new Vector3[4];
		rt.GetWorldCorners(corners);
		Vector3 topLeft = corners[0];

		// Rescale the size appropriately based on the current Canvas scale
		Vector2 scaledSize = new Vector2(scale.x * rt.rect.size.x, scale.y * rt.rect.size.y);

		return new Rect(topLeft, scaledSize);
	}
}
3

More convenient solution:

public static class RectTransformExtensions
{
    public static Rect GetWorldRect(this RectTransform rectTransform)
    {
        Vector3[] corners = new Vector3[4];
        rectTransform.GetWorldCorners(corners);
        // Get the bottom left corner.
        Vector3 position = corners[0];
        
        Vector2 size = new Vector2(
            rectTransform.lossyScale.x * rectTransform.rect.size.x,
            rectTransform.lossyScale.y * rectTransform.rect.size.y);

        return new Rect(position, size);
    }
}
4

Thanks for the tip! Why we cannot use top right and bottom left corner to calculate the rect size?

public static class RectTransformExtensions {
     public static Rect GetWorldRect(this RectTransform rectTransform) {
        Vector3[] corners = new Vector3[4];
        rectTransform.GetWorldCorners(corners);
        return new Rect(corners[0], corners[2] - corners[0]);
     }
 }

Seems to be working fine.

5 
 public static class RectTransformExtensions
    {
        public static Rect GetWorldRect(this RectTransform rectTransform)
        {
            var minX = float.MaxValue;
            var minY = float.MaxValue;
            var maxX = float.MinValue;
            var maxY = float.MinValue;

            var pool = ArrayPool<Vector3>.Shared;
            var corners = pool.Rent(4);
            rectTransform.GetWorldCorners(corners);

            for (var i = 0; i < 4; i++)
            {
                var corner = corners[i];
                minX = Mathf.Min(corner.x, minX);
                minY = Mathf.Min(corner.y, minY);
                maxX = Mathf.Max(corner.x, maxX);
                maxY = Mathf.Max(corner.y, maxY);
            }

            pool.Return(corners);

            var position = new Vector2(minX, minY);
            var size = new Vector2(maxX - minX, maxY - minY);
            return new Rect(position, size);
        }

        public static Rect GetLocalRect(this RectTransform rectTransform)
        {
            var worldRect = rectTransform.GetWorldRect();
            var parent = rectTransform.parent;
            var min = parent.InverseTransformPoint(worldRect.min);
            var max = parent.InverseTransformPoint(worldRect.max);
            return new Rect(min, max - min);
        }
    }