Shader "Custom/StandardSurf"
{
    Properties
    {
        _Color("Color", Color) = (1,1,1,1)
        _MainTex("Albedo (RGBA)", 2D) = "white" {}
        _Glossiness("Smoothness", Range(0,1)) = 0.5
        _Metallic("Metallic", Range(0,1)) = 0.0

        [NoScaleOffset]_DiffuseArray("Transparent Albedo (RGBA)", 2DArray) = "" {}
        _FlipbookFPS("Flipbook FPS", Integer) = 30
        _FlipbookFrames("Flipbook Frames", Integer) = 30
    }

    SubShader
    {
        Tags { "RenderType" = "Transparent" "Queue" = "Transparent" }
        LOD 200

        Blend SrcAlpha OneMinusSrcAlpha
        ZWrite Off
        Cull Back

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

        // Use shader model 3.0 target, to get nicer looking lighting
        #pragma target 3.0

        UNITY_DECLARE_TEX2DARRAY(_DiffuseArray);

        int _FlipbookFPS;
        int _FlipbookFrames;

        sampler2D _MainTex;
        half _Glossiness;
        half _Metallic;
        fixed4 _Color;

        struct Input
        {
            float2 uv_MainTex;
        };

        // Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
        // See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
        // #pragma instancing_options assumeuniformscaling
        UNITY_INSTANCING_BUFFER_START(Props)
        // put more per-instance properties here
        UNITY_INSTANCING_BUFFER_END(Props)

        void surf(Input IN, inout SurfaceOutputStandard o)
        {
            // Common UV for all texture arrays
            float frame = fmod(floor(_Time.y * _FlipbookFPS), _FlipbookFrames);  // Cyclic frame value
            float3 uvw = float3(IN.uv_MainTex, frame);

            float4 diff = UNITY_SAMPLE_TEX2DARRAY(_DiffuseArray, uvw) * _Color;
            o.Albedo = diff.rgb;
            o.Alpha = diff.a;

            // Metallic and smoothness come from slider variables
            o.Metallic = _Metallic;
            o.Smoothness = _Glossiness;
            // o.Alpha = c.a;
        }

        ENDCG
    }

    FallBack "Standard"
}