Hello!

I've been trying again and again to make use of RenderTexture.active and it has never worked once so far.

I tried everything I could think of, using Pro assets and mainly ImageEffects as an example as well.

I tried using different ways to draw a quad to the render texture: Graphics.DrawTexture, Graphics.DrawMeshNow, GL (GL.QUADS), Graphics.Blit. Not once has there been anything drawn into the render texture, which remained completely black and transparent at all times.

This is the most stripped down version I've been trying to make work, in a scene bereft of all but the camera and this script attached to it:

using UnityEngine;
using System.Collections;

public class rdnTxtTst : MonoBehaviour
{
    private RenderTexture rndTxt = null;
    private Material mat = null;

    void Start( )
    {
        rndTxt = Resources.Load( "Textures/RenderTextures/RTtest" ) as RenderTexture;
        mat = new Material( Shader.Find( "DrawPinkAllOver" ) );
    }

    void OnPostRender( )
    {
        RenderTexture oldRndT = RenderTexture.active;
        RenderTexture.active = rndTxt;

        GL.PushMatrix( );
        GL.LoadOrtho( );
        for( int i = 0 ; i < mat.passCount ; i++ )
        {
            mat.SetPass( i );
            GL.Begin( GL.QUADS );

            GL.Vertex3( 0.0f, 0.0f, 0.1f );
            GL.Vertex3( 1.0f, 0.0f, 0.1f );
            GL.Vertex3( 1.0f, 1.0f, 0.1f );
            GL.Vertex3( 0.0f, 1.0f, 0.1f );

            GL.End( );
        }
        GL.PopMatrix( );

        RenderTexture.active = oldRndT;

        Graphics.DrawTexture( new Rect( 0.0f, 0.0f, Screen.width, Screen.height ), rndTxt );
    }
}

And the shader:

Shader "DrawPinkAllOver"
{
    Properties
    {
        _MainTex ("", 2D) = "white" {}
    }

    SubShader
    {
      Cull Off Lighting Off Fog { Color (0,0,0,0) }
   ColorMask RGBA

        Pass
        {
            Blend One Zero
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"

uniform sampler2D _MainTex;

half4 frag (v2f_img i) : COLOR
{
   half4 res = float4( 1.0, 0.0, 1.0, 1.0 );

   return res;
}
ENDCG
        }
    }
}

This version uses GL, but as I said, I won't get any better results using other ways to render a quad on the screen such as Graphics.DrawTexture

Whyyyyyyyyyyy? I'm desperate! Please help!

Thanks in advance.