Helper function to set up an ortho perspective transform.

After calling LoadOrtho, the viewing frustum goes from (0,0,-1) to (1,1,100).
LoadOrtho can be used for drawing primitives in 2D.

	// Draws a triangle over an already drawn triangle
	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.Color(Color.red);
		GL.Begin(GL.TRIANGLES);
		GL.Vertex3(0.25,0.1351,0);
		GL.Vertex3(0.25,0.3,0);
		GL.Vertex3(0.5,0.3,0);
		GL.End();
		GL.Color(Color.yellow);
		GL.Begin(GL.TRIANGLES);
		GL.Vertex3(0.5,0.25,-1);
		GL.Vertex3(0.5,0.1351,-1);
		GL.Vertex3(0.1,0.25,-1);
		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.Color(Color.red);
        GL.Begin(GL.TRIANGLES);
        GL.Vertex3(0.25F, 0.1351F, 0);
        GL.Vertex3(0.25F, 0.3F, 0);
        GL.Vertex3(0.5F, 0.3F, 0);
        GL.End();
        GL.Color(Color.yellow);
        GL.Begin(GL.TRIANGLES);
        GL.Vertex3(0.5F, 0.25F, -1);
        GL.Vertex3(0.5F, 0.1351F, -1);
        GL.Vertex3(0.1F, 0.25F, -1);
        GL.End();
        GL.PopMatrix();
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public mat as Material

	def OnPostRender() as void:
		if not mat:
			Debug.LogError('Please Assign a material on the inspector')
			return
		GL.PushMatrix()
		mat.SetPass(0)
		GL.LoadOrtho()
		GL.Color(Color.red)
		GL.Begin(GL.TRIANGLES)
		GL.Vertex3(0.25F, 0.1351F, 0)
		GL.Vertex3(0.25F, 0.3F, 0)
		GL.Vertex3(0.5F, 0.3F, 0)
		GL.End()
		GL.Color(Color.yellow)
		GL.Begin(GL.TRIANGLES)
		GL.Vertex3(0.5F, 0.25F, -1)
		GL.Vertex3(0.5F, 0.1351F, -1)
		GL.Vertex3(0.1F, 0.25F, -1)
		GL.End()
		GL.PopMatrix()