unity多個貼圖shader

在一個Material上放多個貼圖的測試，比如一個plane上放四個貼圖

Shader "__aaa"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _MainTex2 ("Texture", 2D) = "white" {}
        _MainTex3 ("Texture", 2D) = "white" {}
        _MainTex4 ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        CGINCLUDE
        #include "UnityCG.cginc"
        
        struct appdata
        {
            float4 vertex : POSITION;
            float2 uv : TEXCOORD;
        };

        struct v2f
        {
            float4 vertex : SV_POSITION;
            float2 uv : TEXCOORD;
        };
        
        ENDCG
        
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                clip(i.uv-1);
                fixed4 col = tex2D(_MainTex, i.uv);
                return col;
            }
            ENDCG
        }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
        

            sampler2D _MainTex2;
            float4 _MainTex2_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex2);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                clip(1-i.uv);
                fixed4 col = tex2D(_MainTex2, i.uv);
                return col;
            }
            ENDCG
        }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            

            sampler2D _MainTex3;
            float4 _MainTex3_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex3);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                clip(i.uv.x-1);
                clip(1-i.uv.y);
                fixed4 col = tex2D(_MainTex3, i.uv);
                return col;
            }
            ENDCG
        }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            

            sampler2D _MainTex4;
            float4 _MainTex4_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex4);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                clip(i.uv.y-1);
                clip(1-i.uv.x);
                fixed4 col = tex2D(_MainTex4, i.uv);
                return col;
            }
            ENDCG
        }
    }
}

貼圖tiling都設爲2,2