[Unity] Image Effectでフェードアウト ref: http://qiita.com/edo_m18/items/b0670b0274742fa1714e

fader.cs

using UnityEngine;
using System.Collections;

public class Fader : MonoBehaviour {

    [SerializeField]
    Material m_Material;

    void OnRenderImage(RenderTexture src, RenderTexture dest) {
        Graphics.Blit(src, dest, m_Material);
    }
}

file1.txt

fixed4 frag (v2f i) : SV_Target
{
    fixed4 col   = tex2D(_MainTex, i.uv);        // 1)
    fixed4 black = 1 - fixed4(_Time.yyy / 2, 1);  // 2)
    col *= black;                               // 3)
    return col;                                 // 4)
}

file2.txt

1 - fixed4(_Time.yyy / 2, 1)

file3.txt

Shader "Custom/Fade"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off ZTest Always

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                o.uv = v.uv;
                return o;
            }

            uniform float _Timer;
            sampler2D _MainTex;

            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv);
                fixed4 black = 1 - fixed4(_Time.yyy / 2, 1);
                col *= black;
                return col;
            }
            ENDCG
        }
    }
}