Unity 3D Make an object full the screen.

FillScreen.cs

using UnityEngine;

public class FillScreen:MonoBehaviour
{
  void Update() {
    Camera cam = Camera.main;

    float pos = (cam.nearClipPlane + 0.01f);

    transform.position = cam.transform.position + cam.transform.forward * pos;
    transform.LookAt (cam.transform);
    // transform.Rotate (90.0f, 0.0f, 0.0f);

    float h = (Mathf.Tan(cam.fieldOfView*Mathf.Deg2Rad*0.5f)*pos*2f) /10.0f;

    transform.localScale = new Vector3(h*cam.aspect,1.0f, h);
  }
}