Unity ShaderLab "Custom/UI/Filtered" uGUIのImageに空間フィルタをかけるためのシェーダー

UI_Filtered.shader

Shader "Custom/UI/Filtered"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
		_Mat0("Mat0", Vector) = (1,0,-1, -1)
		_Mat1("Mat1", Vector) = (2,0,-2, -1)
		_Mat2("Mat2", Vector) = (1,0,-1, -1)
		_Cutout("Cutout", Range(0.0,1.0)) = 0
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile __ UNITY_UI_ALPHACLIP

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord  : TEXCOORD0;
                float4 worldPosition : TEXCOORD1;
                UNITY_VERTEX_OUTPUT_STEREO
            };

            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                OUT.worldPosition = v.vertex;
                OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

                OUT.texcoord = v.texcoord;

                OUT.color = v.color * _Color;
                return OUT;
            }

            sampler2D _MainTex;
			float4 _MainTex_TexelSize;
			float4 _Mat0;
			float4 _Mat1;
			float4 _Mat2;
			float _Cutout;
			uniform float3x3 _matrix;

            fixed4 frag(v2f IN) : SV_Target
            {
				float4 color; 
				_matrix[0][0] = _Mat0[0];
				_matrix[0][1] = _Mat0[1];
				_matrix[0][2] = _Mat0[2];
				_matrix[1][0] = _Mat1[0];
				_matrix[1][1] = _Mat1[1];
				_matrix[1][2] = _Mat1[2];
				_matrix[2][0] = _Mat2[0];
				_matrix[2][1] = _Mat2[1];
				_matrix[2][2] = _Mat2[2];
				

				for(int u = -1; u <= 1; u++){
					for(int v = -1; v <= 1; v++){
					float x = clamp(IN.texcoord.x + u*_MainTex_TexelSize.x,0,1);
					float y = clamp(IN.texcoord.y + v*_MainTex_TexelSize.y,0,1);
                    color += ((tex2D(_MainTex, float2(x,y)) + _TextureSampleAdd) * IN.color) * _matrix[u+1][v+1];
					}
				}
				float gray = color.r*0.3 + color.g*0.6 + color.b*0.1;
				if(_Cutout==0 || gray > _Cutout)color.a = tex2D(_MainTex,IN.texcoord).a;

                color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                return color;
            }
        ENDCG
        }
    }
}