Shader "Diffuse - Worldspace"
{
  Properties
  {
    _Color ("Main Color", Color) = (1,1,1,1)
    _MainTex ("Base (RGB)", 2D) = "white" {}
    _Scale ("Texture Scale", Float) = 1.0
  }

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

    CGPROGRAM
    #pragma surface surf Lambert

    sampler2D _MainTex;
    fixed4 _Color;
    float _Scale;

    struct Input
    {
      float3 worldNormal;
      float3 worldPos;
    };

    void surf (Input IN, inout SurfaceOutput o)
    {
      float2 UV;
      fixed4 c;

      if(abs(IN.worldNormal.x)>0.5)
      {
        UV = IN.worldPos.yz; // side
        c = tex2D(_MainTex, UV* _Scale); // use WALLSIDE texture
      }
      else if(abs(IN.worldNormal.z)>0.5)
      {
        UV = IN.worldPos.xy; // front
        c = tex2D(_MainTex, UV* _Scale); // use WALL texture
      }
      else
      {
        UV = IN.worldPos.xz; // top
        c = tex2D(_MainTex, UV* _Scale); // use FLR texture
      }

      o.Albedo = c.rgb * _Color;
    }
    ENDCG
  }

  Fallback "VertexLit"
}

CGPROGRAM
    // Physically based Standard lighting model, and enable shadows on all light types
    #pragma surface surf Standard fullforwardshadows vertex:vert

    void vert(inout appdata_full v) {

        // Get the worldspace normal after transformation, and ensure it's unit length.
        float3 n = normalize(mul(unity_ObjectToWorld, v.normal).xyz);

                // Pick a direction for our texture's vertical "v" axis.
                // Default for floors/ceilings:
                float3 vDirection = float3(0, 0, 1);

        // For non-horizontal planes, we'll choose
                // the closest vector in the polygon's plane to world up.
                if(abs(n.y) < 1.0f)) {
                     vDirection = normalize(float3(0, 1, 0) - n.y * n);
                }

        // Get the perpendicular in-plane vector to use as our "u" direction.
        float3 uDirection = normalize(cross(n, vDirection));

        // Get the position of the vertex in worldspace.
        float3 worldSpace = mul(unity_ObjectToWorld, v.vertex).xyz;

        // Project the worldspace position of the vertex into our texturing plane,
        // and use this result as the primary texture coordinate.
        v.texcoord.xy = float2(dot(worldSpace, uDirection), dot(worldSpace, vDirection));
    }