Shader "Erosion/Atmosphere"
{
	Properties
	{
		_VaporField("Base (RGB)", 2D) = "white" {}
		_MaxVaporForBlackColor("MaxVaporForBlackColor", Float) = 0.1
	}
	SubShader
	{
		Tags { "RenderType" = "Opaque" }
		LOD 200

		CGPROGRAM
		#pragma exclude_renderers gles
		#pragma surface surf Lambert vertex:vert
		#pragma target 3.0
		#pragma glsl

		sampler2D _VaporField;
		uniform float _AtmoHeight, _ScaleY, _MaxVaporForBlackColor;

		struct Input
		{
			float2 uv_MainTex;
		};



		void vert(inout appdata_full v)
		{
			v.tangent = float4(1,0,0,1);

			v.vertex.y += _AtmoHeight * _ScaleY;
		}

		/*float3 FindNormal(float2 uv, float u)
        {

        	float ht0 = GetTotalHeight(tex2D(_MainTex, uv + float2(-u, 0)));
            float ht1 = GetTotalHeight(tex2D(_MainTex, uv + float2(u, 0)));
            float ht2 = GetTotalHeight(tex2D(_MainTex, uv + float2(0, -u)));
            float ht3 = GetTotalHeight(tex2D(_MainTex, uv + float2(0, u)));

            float2 _step = float2(1.0, 0.0);

            float3 va = normalize(float3(_step.xy, ht1-ht0));
            float3 vb = normalize(float3(_step.yx, ht2-ht3));

           return cross(va,vb);
        }*/

		void surf(Input IN, inout SurfaceOutput o)
		{
			float vapor = tex2D(_VaporField, IN.uv_MainTex).x;
			//o.Albedo.r = clamp( vapor / _MaxVaporForBlackColor, 0.0, 1.0);
			o.Albedo.r = vapor / _MaxVaporForBlackColor;
			//o.Albedo.r = 1+ IN.uv_MainTex.x*100;
			o.Alpha = 1.0;
			//float3 n = FindNormal(IN.uv_MainTex, 1.0 / _TexSize);
			o.Normal = fixed3(0,0,0);

		}
		ENDCG
	}
	FallBack "Diffuse"
}