// SpaceUnity: Shader from Unity wiki
Shader "SpaceUnity/PlanetStandard"
    {        	    	
      //Earth Shader created by Julien Lynge @ Fragile Earth Studios
      //Upgrade of a shader originally put together in Strumpy Shader Editor by Clamps
      //Feel free to use and share this shader, but please include this attribution
 
      Properties 
      {
    _MainTex("_MainTex", 2D) = "black" {}
    _Normals("_Normals", 2D) = "black" {}
    _Lights("_Lights", 2D) = "black" {}
    _LightScale("_LightScale", Float) = 1
    _AtmosNear("_AtmosNear", Color) = (0.1686275,0.7372549,1,1)
    _AtmosFar("_AtmosFar", Color) = (0.4557808,0.5187039,0.9850746,1)
    _AtmosFalloff("_AtmosFalloff", Float) = 3
 
      }
 
      SubShader 
      {
        Tags
        {
    "Queue"="Geometry"
    "IgnoreProjector"="False"
    "RenderType"="Opaque"
 
        }
 
    Cull Back
    ZWrite On
    ZTest LEqual
    ColorMask RGBA
    Fog{
    }
 
        CGPROGRAM
    #pragma surface surf BlinnPhongEditor
    #pragma target 2.0
 
    sampler2D _MainTex;
    sampler2D _Normals;
    sampler2D _Lights;
    float _LightScale;
    float4 _AtmosNear;
    float4 _AtmosFar;
    float _AtmosFalloff;
 
          struct EditorSurfaceOutput {
            half3 Albedo;
            half3 Normal;
            half3 Emission;
            half3 Gloss;
            half Specular;
            half Alpha;
            half4 Custom;
          };
 
          inline half4 LightingBlinnPhongEditor_PrePass (EditorSurfaceOutput s, half4 light)
          {
    half3 spec = light.a * s.Gloss;
    half4 c;
    c.rgb = (s.Albedo * light.rgb + light.rgb * spec);
    c.g -= .01 * s.Alpha;
    c.r -= .03 * s.Alpha;
    c.rg += min(s.Custom, s.Alpha);
    c.b += 0.75 * min(s.Custom, s.Alpha);
    c.b = saturate(c.b + s.Alpha * .02);
    c.a = 1.0;
    return c;
 
          }
 
          inline half4 LightingBlinnPhongEditor (EditorSurfaceOutput s, half3 lightDir, half3 viewDir, half atten)
          {
            half3 h = normalize (lightDir + viewDir);
 
            half diff = max (0, dot ( lightDir, s.Normal ));
 
            float nh = max (0, dot (s.Normal, h));
            float spec = pow (nh, s.Specular*128.0);
 
            half4 res;
            res.rgb = _LightColor0.rgb * diff;
            res.w = spec * Luminance (_LightColor0.rgb);
            res *= atten * 2.0;
 
        //s.Alpha is now 1 where the earth is dark.  The value of night lights has been saved to Alpha
        half invdiff = 1 - saturate(16 * diff);
        s.Alpha = invdiff;
 
            return LightingBlinnPhongEditor_PrePass( s, res );
          }
 
          struct Input {
            float3 viewDir;
    float2 uv_MainTex;
    float2 uv_Normals;
    float2 uv_Lights;
 
          };
 
          void surf (Input IN, inout EditorSurfaceOutput o) {
            o.Gloss = 0.0;
            o.Specular = 0.0;
            o.Custom = 0.0;
            o.Alpha = 1.0;
 
        float4 Fresnel0_1_NoInput = float4(0,0,1,1);
        float4 Fresnel0=(1.0 - dot( normalize( float4( IN.viewDir.x, IN.viewDir.y,IN.viewDir.z,1.0 ).xyz), normalize( Fresnel0_1_NoInput.xyz ) )).xxxx;
        float4 Pow0=pow(Fresnel0,_AtmosFalloff.xxxx);
        float4 Saturate0=saturate(Pow0);
        float4 Lerp0=lerp(_AtmosNear,_AtmosFar,Saturate0);
        float4 Multiply1=Lerp0 * Saturate0;
        float4 Sampled2D2=tex2D(_MainTex,IN.uv_MainTex.xy);
        float4 Add0=Multiply1 + Sampled2D2;
        float4 Sampled2D0=tex2D(_Normals,IN.uv_Normals.xy);
        float4 UnpackNormal0=float4(UnpackNormal(Sampled2D0).xyz, 1.0);
 
        o.Albedo = Add0;
        o.Normal = UnpackNormal0;
        //o.Emission = Multiply0;
            o.Emission = 0.0;
 
            //float4 Multiply0=Sampled2D1 * _LightScale.xxxx;
        o.Custom = tex2D(_Lights,IN.uv_Lights.xy).r * _LightScale;
 
            o.Normal = normalize(o.Normal);
          }
        ENDCG
      }
      Fallback "Diffuse"
    }