Replacement for Unity's StandaloneInputModule, world-space UI now reacts to first person locked cursor, screen center being the pointer position.

FirstPersonInputModule.cs

using UnityEngine;
using UnityEngine.EventSystems;
	
public class FirstPersonInputModule : StandaloneInputModule {
	protected override MouseState GetMousePointerEventData(int id) {
		var lockState = Cursor.lockState;
		Cursor.lockState = CursorLockMode.None;
		var mouseState = base.GetMousePointerEventData(id);
		Cursor.lockState = lockState;
		return mouseState;
	}

	protected override void ProcessMove(PointerEventData pointerEvent) {
		var lockState = Cursor.lockState;
		Cursor.lockState = CursorLockMode.None;
		base.ProcessMove(pointerEvent);
		Cursor.lockState = lockState;
	}

	protected override void ProcessDrag(PointerEventData pointerEvent) {
		var lockState = Cursor.lockState;
		Cursor.lockState = CursorLockMode.None;
		base.ProcessDrag(pointerEvent);
		Cursor.lockState = lockState;
	}
}