Shader "Custom/SimpleBlend" {
    Properties {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _BlendTex ("Blend Texture", 2D) = "white" {}
    }
    
    SubShader {
        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 pos : SV_POSITION;
            };

            sampler2D _MainTex;
            sampler2D _BlendTex;

            v2f vert(appdata v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target {
                fixed4 base = tex2D(_MainTex, i.uv);
                fixed4 blend = tex2D(_BlendTex, i.uv);
                return lerp(base, blend, blend.a); // Alpha混合
            }
            ENDCG
        }
    }
}