HandleUtility.GUIPointToScreenPixelCoordinate

Description

Converts a 2D GUI position to screen pixel coordinates.

The bottom-left of the screen or window is at (0, 0). The top-right of the screen or window is at (Screen.width, Screen.height).

See Also: Input.mousePosition and Camera.ScreenPointToRay.

using UnityEngine;
using UnityEditor;

public class ExampleScript : MonoBehaviour
{
    public static Ray GUIPointToWorldRay(Vector2 guiPos, Camera camera)
    {
        Vector2 screenPixelPos = HandleUtility.GUIPointToScreenPixelCoordinate(guiPos);
        return Camera.main.ScreenPointToRay(screenPixelPos);
    }
}