Shader "Minecraft/TransparentBlocks" {
    Properties {
        _MainTex ("Block Texture Atlas", 2D) = "white" {}
    }
    
    SubShader {
        Tags {"Queue" = "AlphaTest" "IgnoreProjector" = "True" "RenderType" = "TransparentCutout"}
        LOD 100
        Lighting Off
        
        Pass {
            CGPROGRAM
                #pragma vertex vertFunction
                #pragma fragment fragFunction
                #pragma target 2.0
    
                #include "UnityCG.cginc"
    
                struct appdata {
                    float4 vertex : POSITION;
                    float2 uv : TEXCOORD0;
                    float4 color : COLOR;
                };
    
                struct v2f {
                    float4 vertex : SV_POSITION;
                    float2 uv : TEXCOORD0;
                    float4 color : COLOR;
                };
    
                sampler2D _MainTex;
                float GlobalLightLevel;
                float minGlobalLightLevel;
                float maxGlobalLightLevel;
                
                v2f vertFunction(appdata v) {
                    v2f o;
    
                    o.vertex = UnityObjectToClipPos(v.vertex);
                    o.uv = v.uv;
                    o.color = v.color;
    
                    return o;
                }
    
                fixed4 fragFunction(v2f i) : SV_Target {
                    fixed4 col = tex2D(_MainTex, i.uv);
                    clip(col.a - 1);

                    float shade = (maxGlobalLightLevel - minGlobalLightLevel) * GlobalLightLevel + minGlobalLightLevel;
                    shade *= i.color.a;
                    shade = clamp(1 - shade, minGlobalLightLevel, maxGlobalLightLevel);
                    //const float4 localLightLevel = clamp(GlobalLightLevel + i.color.a, 0, 1);
                    
                    col = lerp(col, float4(0, 0, 0, 1), shade);
    
                    return col;
                }
            ENDCG
        }
    }
}