Graphics_Blit.cs

using UnityEngine;
using System.Collections;

// Example: Using Graphics.Blit to draw a full screen texture, with particle shader
// Usage: Attach to Main Camera
// Optional: Assign some texture into the displayTexture field in inspector

namespace UnityLibrary
{
    public class Graphics_Blit : MonoBehaviour
    {
        public Texture displayTexture; // assign texture you want to blit fullscreen
        Material mat; // material(shader) to use for blitting

        void Awake()
        {
            if (displayTexture == null) displayTexture = Texture2D.whiteTexture; // use white texture, if nothing is set

            // use particle shader for the Blit material
            var shader = Shader.Find("Particles/Multiply (Double)");
            mat = new Material(shader);
        }

        // This function is called only if the script is attached to the camera and is enabled
        void OnPostRender()
        {
            // Copies source texture into destination render texture with a shader
            // Destination RenderTexture is null to blit directly to screen
            Graphics.Blit(displayTexture, null, mat);
        }
    }
}