RenderGUIToTexture.cs

using UnityEngine;
using System.Collections;

[RequireComponent (typeof (Renderer))]
public class RenderGUIToTexture : MonoBehaviour
{
	public RenderTexture texture;
	public Texture2D background;
	
	
	void Start ()
	{
		if (texture == null || background == null)
		{
			Debug.LogError ("Both texture and background properties need to be set. Please correct and restart.");
			enabled = false;
			return;
		}
		
		renderer.material.mainTexture = texture;
	}


	void OnGUI ()
	{
		if (Event.current.type == EventType.Repaint)
		{
			RenderTexture active = RenderTexture.active;
			RenderTexture.active = texture;
			
			//GUI.matrix = thisIsFiddly;
			
			GUI.DrawTexture (new Rect (0.0f, 0.0f, texture.width, texture.height), background);
			GUI.skin.GetStyle ("Box").Draw (new Rect (20.0f, 20.0f, 100.0f, 30.0f), "Hello, world!", false, false, false, false);
			
			RenderTexture.active = active;
		}
	}
}