Glow Shader

Shader "Hidden/GlowCompose" {

Properties {
     ("Glow Amount", Color) = (1,1,1,1)
    _MainTex ("", 2D) = "white" {}
}

Category {
    ZTest Always Cull Off ZWrite Off Fog { Mode Off }
    Blend One One

    Subshader {
        Pass {
            CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #pragma fragmentoption ARB_precision_hint_fastest

                #include "UnityCG.cginc"

                struct v2f {
                    float4 pos : POSITION;
                    half2 uv : TEXCOORD0;
                };

                float4 _MainTex_TexelSize;
                float4 _BlurOffsets;

                v2f vert (appdata_img v)
                {
                    v2f o;
                    o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
                    o.uv = MultiplyUV (UNITY_MATRIX_TEXTURE0, v.texcoord.xy);
                    return o;
                }

                sampler2D _MainTex;
                fixed4 _Color;

                fixed4 frag( v2f i ) : COLOR
                {
                    return 2.0f * _Color * tex2D( _MainTex, i.uv );
                }
            ENDCG
        }
    }

    SubShader {
        Pass {
            SetTexture [_MainTex] {constantColor [_Color] combine constant * texture DOUBLE}
        }
    }
}

Fallback off

}