Shader "Custom/ShadowOnly"
{
    Properties
    {
        _Color ("Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
		_AttenLimit("Attenuation Limit", Float) = 0
		_AttenScale("Attenuation Scale", Float) = 1
		_AttenOffset("Attenuation Offset", Float) = 0
		//_Glossiness ("Smoothness", Range(0,1)) = 0.5
        //_Metallic ("Metallic", Range(0,1)) = 0.0
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 200

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

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

        sampler2D _MainTex;

        struct Input
        {
            float2 uv_MainTex;
			float4 shadowCoord;
        };

        half _Glossiness;
        half _Metallic;
        fixed4 _Color;

		uniform float _AttenLimit;
		uniform float _AttenScale;
		uniform float _AttenOffset;

		#include "AutoLight.cginc"

        // 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 vert(inout appdata_full v, out Input o) {
			UNITY_INITIALIZE_OUTPUT(Input, o);
			o.shadowCoord = mul(unity_WorldToShadow[0], mul(unity_ObjectToWorld, v.vertex));
		}

        void surf (Input IN, inout SurfaceOutputStandard o)
        {
            // Albedo comes from a texture tinted by color
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			float shadow = 1;
#if defined (SHADOWS_SCREEN)
			shadow = unitySampleShadow(IN.shadowCoord);
#endif
			o.Albedo = c.rgb * shadow;
            // Metallic and smoothness come from slider variables
            //o.Metallic = _Metallic;
            //o.Smoothness = _Glossiness;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}