// Draws a line from the bottom right
// to the top left of the Screen
// Using GL.Vertex
var mat : Material;

function OnPostRender() {
    if (!mat) {
        Debug.LogError("Please Assign a material on the inspector");
        return;
    }
    GL.PushMatrix();
    mat.SetPass(0);
    GL.LoadOrtho();
    GL.Begin(GL.LINES);
    GL.Vertex(Vector3(1,0,0));
    GL.Vertex(Vector3(0,1,0));
    GL.End();
    GL.PopMatrix();
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Material mat;
    void OnPostRender() {
        if (!mat) {
            Debug.LogError("Please Assign a material on the inspector");
            return;
        }
        GL.PushMatrix();
        mat.SetPass(0);
        GL.LoadOrtho();
        GL.Begin(GL.LINES);
        GL.Vertex(new Vector3(1, 0, 0));
        GL.Vertex(new Vector3(0, 1, 0));
        GL.End();
        GL.PopMatrix();
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public mat as Material

    def OnPostRender():
        if not mat:
            Debug.LogError('Please Assign a material on the inspector')
            return
        GL.PushMatrix()
        mat.SetPass(0)
        GL.LoadOrtho()
        GL.Begin(GL.LINES)
        GL.Vertex(Vector3(1, 0, 0))
        GL.Vertex(Vector3(0, 1, 0))
        GL.End()
        GL.PopMatrix()