Shader "Terrain" 
{
    Properties 
    {
       _TerrainColor  ("Terrain Color", 2D)  = "white" {}
       _TerrainNormal ("Terrain Normal", 2D) = "white" {}
       _WallColor  ("Wall Color", 2D)  = "white" {}
       _WallNormal ("Wall Normal", 2D) = "white" {}
    }
    
    SubShader {
      Tags { "RenderType" = "Opaque" }
      
      CGPROGRAM
      #pragma surface surf Standard
      
      struct Input {
        float4 color: COLOR;
        float3 worldPos;
        float2 uv_TerrainColor;
      };
      
      sampler2D _TerrainColor;
      sampler2D _TerrainNormal;
      sampler2D _WallColor;
      sampler2D _WallNormal;
      
      void surf (Input IN, inout SurfaceOutputStandard o) {
        float t = saturate(IN.color.r * 4 - 3);
      
        o.Albedo = lerp(tex2D(_TerrainColor, IN.worldPos.xz).rgb, tex2D(_WallColor, IN.uv_TerrainColor).rgb, t);
        o.Normal = UnpackNormal(lerp(tex2D(_TerrainNormal, IN.worldPos.xz), tex2D(_WallNormal, IN.uv_TerrainColor), t));
      }
      
      ENDCG
    } 
    
    Fallback "Diffuse"
}
     
