// Shaders/ImageBlend.shader
Shader "Custom/ImageBlend" {
    Properties {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _BlendTex ("Blend Texture", 2D) = "white" {}
    }

    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200

        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;
            };

            sampler2D _MainTex;
            sampler2D _BlendTex;

            v2f vert (appdata v) {
                v2f o;
                o.vertex = 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);
                
                // 使用Alpha混合
                fixed4 result = lerp(base, blend, blend.a);
                return result;
            }
            ENDCG
        }
    }
}