Shader "Unlit/BlackAreaBlit2"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _MaskTex ("Mask Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { 
            "RenderType" = "Opaque"
            "RenderPipeline" = "UniversalPipeline"
        }
        LOD 100

        Pass
        {
            ZTest Off
            ZWrite Off
            Cull Off
            
            HLSLPROGRAM
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #pragma vertex vert
            #pragma fragment frag

            struct appdata
            {
                float4 positionOS : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 positionHCS : SV_POSITION;
            };

            TEXTURE2D(_MainTex);
            SAMPLER(sampler_MainTex);

            TEXTURE2D(_MaskTex);
            SAMPLER(sampler_MaskTex);

            CBUFFER_START(UnityPerMaterial)
                float4 _MainTex_ST;
                float4 _MaskTex_ST;
            CBUFFER_END
            
            v2f vert (appdata v)
            {
                v2f o;
                o.positionHCS = TransformObjectToHClip(v.positionOS.xyz);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            half4 frag (v2f i) : SV_Target
            {
                // sample the texture
                half4 col = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv);
                half4 mask = SAMPLE_TEXTURE2D(_MaskTex, sampler_MaskTex, i.uv);
                float minAlpha = 0.2;
                if (mask.r > 0)
                {
                    float scale = mask.r * 1;
                    scale = min(scale, 0.6);
                    scale = max(scale, minAlpha);
                    return col * scale;
                }
                return col * minAlpha;
            }
            ENDHLSL
        }
    }
}