struct appdata_full {
    float4 vertex : POSITION;
    float3 normal : NORMAL;
    float4 tangent : TANGENT;
    float2 texcoord;  
};
float4x4 UNITY_MATRIX_IT_MV;
float4x4 UNITY_MATRIX_MVP;
fixed4 UNITY_LIGHTMODEL_AMBIENT;

struct v2f {
    float4 pos : SV_POSITION;
    float2 uv : TEXCOORD0;
    float3 color : TEXCOORD1; 
    float3 backContrib : TEXCOORD2;
    float3 nl : TEXCOORD3;
    float3 nh : TEXCOORD4;
};

float4 _TerrainTreeLightColors[4];

sampler2D _MainTex;
sampler2D _BumpSpecMap;
sampler2D _TranslucencyMap;
fixed _Cutoff;

fixed3 _TranslucencyColor;
fixed4 _SpecColor;

fixed4 main (v2f i) : COLOR
{
    fixed4 col = tex2D (_MainTex, i.uv);
    clip (col.a - _Cutoff);
    
    fixed3 albedo = col.rgb * i.color;
    
    half specular = tex2D (_BumpSpecMap, i.uv).r * 128.0;
    
    fixed4 trngls = tex2D (_TranslucencyMap, i.uv);
    half gloss = trngls.a;
    
    half3 light = UNITY_LIGHTMODEL_AMBIENT * albedo;
    
    half3 backContribs = i.backContrib * trngls.b;
    
    for (int j = 0; j < 3; j++)
    {
        half3 lightColor = _TerrainTreeLightColors[j].rgb;
        half3 translucencyColor = backContribs[j] * _TranslucencyColor;
        
        half nl = i.nl[j];      
        half nh = i.nh[j];
        half spec = pow (nh, specular) * gloss;
        light += (albedo * (translucencyColor + nl) + _SpecColor.rgb * spec) * lightColor;
    }
    
    fixed4 c;
    c.rgb = light * 2.0;
    c.a = 1;
    return c;
}