Take a screenshot using a rect transform without it being affected by the screen size in Unity using C#

One possible way to take a screenshot using a rect transform without it being affected by the screen size in Unity using C#  is to use the Camera.WorldToScreenPoint method to convert the four corners of the rect transform to screen points. Then, you can use Texture.ReadPixels with a Rect as calculated from the screen points to save it into a texture. You may need to adjust the y-axis depending on your camera settings.

Here are some possible steps and c# code example for taking a screenshot using a rect transform:

• Assign the rect transform object that you want to screenshot to a variable (e.g. _objToScreenshot) .
• Convert the four corners of the rect transform to world points using _objToScreenshot.GetWorldCorners method 1.
• Convert the world points to screen points using Camera.WorldToScreenPoint method .
• Adjust the y-axis if needed by subtracting it from Screen.height .
• Calculate the width and height of the rect transform in screen space by subtracting the minimum x and y values from the maximum x and y values .
• Create a new texture with the width and height of the rect transform 1.
• Use Texture.ReadPixels with a Rect as calculated from the screen points to save it into the texture .
• Encode the texture as PNG and save it to disk using System.IO.File.WriteAllBytes method 1.

An example code for this method is:

using System.Collections;
using UnityEngine;
using UnityEngine.UI;

public class TakeScreenshotAndSave : MonoBehaviour
{
    //Object To Screenshot
    [SerializeField]
    private RectTransform _objToScreenshot;

    //Set the button to take a screenshot when pressed
    public Button btnTakeScreenshot;

    private void Start()
    {
        btnTakeScreenshot.onClick.AddListener(TakeScreenShot);
    }

    private void TakeScreenShot()
    {
        //Get four corners of object in world space
        Vector3[] v = new Vector3[4];
        _objToScreenshot.GetWorldCorners(v);

        //Convert world space corners to screen space
        Vector2[] v2 = new Vector2[4];
        for (int i = 0; i < 4; i++)
        {
            v2[i] = Camera.main.WorldToScreenPoint(v[i]);
            //Adjust y-axis if needed
            v2[i].y = Screen.height - v2[i].y;
        }

        //Calculate width and height of object in screen space
        float width = Mathf.Abs(v2[0].x - v2[1].x);
        float height = Mathf.Abs(v2[0].y - v2[1].y);

        //Using that size, create a new texture.
        Texture2D tex = new Texture2D((int)width, (int)height);

        //Read pixels from screen into texture
        tex.ReadPixels(new Rect(v2[0], new Vector2(width, height)), 0, 0);
        
        //Encode texture as PNG and save it to disk
        byte[] bytes = tex.EncodeToPNG();
        
		//You can change this path according to your needs
		string path = Application.dataPath + "/screenshot.png";
		
		System.IO.File.WriteAllBytes(path, bytes);
		
		Debug.Log("Saved screenshot at " + path);
        
    }
}