untiy GLで簡単に線枠を描く

最近機能して、画面に枠を描いて私が表示したいものを強調したいので、簡単にGLを使って線枠を書く方法を使って、2つの点を伝えればいいのです

using UnityEngine;
using System.Collections;

public class DrawLine : MonoBehaviour {

public Material mat;
private Vector2 screenStartPos, screenEndPos;

void OnPostRender(Vector2 pos1, Vector2 pos2)
    {
        GL.PushMatrix();
        mat.SetPass(0);
        GL.LoadOrtho();
        GL.Begin(GL.LINES);
        GL.Color(Color.red);
        GL.Vertex3(pos1.x / Screen.width, pos1.y / Screen.height, 0);
        GL.Vertex3(pos2.x / Screen.width, pos1.y / Screen.height, 0);
        GL.Vertex3(pos2.x / Screen.width, pos1.y / Screen.height, 0);
        GL.Vertex3(pos2.x / Screen.width, pos2.y / Screen.height, 0);
        GL.Vertex3(pos2.x / Screen.width, pos2.y / Screen.height, 0);
        GL.Vertex3(pos1.x / Screen.width, pos2.y / Screen.height, 0);
        GL.Vertex3(pos1.x / Screen.width, pos2.y / Screen.height, 0);
        GL.Vertex3(pos1.x / Screen.width, pos1.y / Screen.height, 0);
        GL.End();
        GL.PopMatrix();
    }
}