// Draw a red Quad that covers all the view port, and the when space is pressed
// the viewport gets expanded to the whole screen and stretch the contents inside
var mat : Material;
private var stretch : boolean = false;

function Update() {
    if(Input.GetKeyDown(KeyCode.Space)) {
        if(stretch) {
            stretch = false;
        } else {
            stretch = true;
        }
    }
}

function OnPostRender() {
    if (!mat) {
        Debug.LogError("Please Assign a material on the inspector");
        return;
    }
    GL.PushMatrix();
    mat.SetPass(0);
    GL.LoadPixelMatrix();
    if(stretch) {
        GL.Viewport(Rect(0,0,Screen.width,Screen.height));
    } else {
        GL.Viewport(Rect(0,0,Screen.width/2,Screen.height));
    }
    GL.Color(Color.red);
    GL.Begin(GL.QUADS);
    GL.Vertex3(0,0,0);
    GL.Vertex3(0,Screen.height,0);
    GL.Vertex3(Screen.width,Screen.height,0);
    GL.Vertex3(Screen.width,0,0);
    GL.Color(Color.yellow);
    GL.End();
    GL.Begin(GL.TRIANGLES);
    GL.Vertex3(Screen.width/2,Screen.height/4,1);
    GL.Vertex3(Screen.width/4,Screen.height/2,1);
    GL.Vertex3(Screen.width - Screen.width/4,Screen.height/2,1);
    GL.End();
    GL.PopMatrix();
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Material mat;
    private bool stretch = false;
    void Update() {
        if (Input.GetKeyDown(KeyCode.Space))
            if (stretch)
                stretch = false;
            else
                stretch = true;
        
    }
    void OnPostRender() {
        if (!mat) {
            Debug.LogError("Please Assign a material on the inspector");
            return;
        }
        GL.PushMatrix();
        mat.SetPass(0);
        GL.LoadPixelMatrix();
        if (stretch)
            GL.Viewport(new Rect(0, 0, Screen.width, Screen.height));
        else
            GL.Viewport(new Rect(0, 0, Screen.width / 2, Screen.height));
        GL.Color(Color.red);
        GL.Begin(GL.QUADS);
        GL.Vertex3(0, 0, 0);
        GL.Vertex3(0, Screen.height, 0);
        GL.Vertex3(Screen.width, Screen.height, 0);
        GL.Vertex3(Screen.width, 0, 0);
        GL.Color(Color.yellow);
        GL.End();
        GL.Begin(GL.TRIANGLES);
        GL.Vertex3(Screen.width / 2, Screen.height / 4, 1);
        GL.Vertex3(Screen.width / 4, Screen.height / 2, 1);
        GL.Vertex3(Screen.width - Screen.width / 4, Screen.height / 2, 1);
        GL.End();
        GL.PopMatrix();
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public mat as Material

    private stretch as bool = false

    def Update():
        if Input.GetKeyDown(KeyCode.Space):
            if stretch:
                stretch = false
            else:
                stretch = true

    def OnPostRender():
        if not mat:
            Debug.LogError('Please Assign a material on the inspector')
            return
        GL.PushMatrix()
        mat.SetPass(0)
        GL.LoadPixelMatrix()
        if stretch:
            GL.Viewport(Rect(0, 0, Screen.width, Screen.height))
        else:
            GL.Viewport(Rect(0, 0, (Screen.width / 2), Screen.height))
        GL.Color(Color.red)
        GL.Begin(GL.QUADS)
        GL.Vertex3(0, 0, 0)
        GL.Vertex3(0, Screen.height, 0)
        GL.Vertex3(Screen.width, Screen.height, 0)
        GL.Vertex3(Screen.width, 0, 0)
        GL.Color(Color.yellow)
        GL.End()
        GL.Begin(GL.TRIANGLES)
        GL.Vertex3((Screen.width / 2), (Screen.height / 4), 1)
        GL.Vertex3((Screen.width / 4), (Screen.height / 2), 1)
        GL.Vertex3((Screen.width - (Screen.width / 4)), (Screen.height / 2), 1)
        GL.End()
        GL.PopMatrix()