Unlit Texture + Realtime Shadows shader

UnlitTextureShadows.shader

Shader "Universal Render Pipeline/Custom/UnlitTextureShadows"
{
    Properties
    {
        [MainColor] _BaseColor("BaseColor", Color) = (1,1,1,1)
        [MainTexture] _BaseMap("BaseMap", 2D) = "white" {}
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalRenderPipeline"}

        Pass
        {
            Tags { "LightMode"="UniversalForward" }

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            // -------------------------------------
            // Universal Render Pipeline keywords
            #pragma multi_compile _ _MAIN_LIGHT_SHADOWS
            #pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE
            #pragma multi_compile _ _SHADOWS_SOFT

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
                      
            struct Attributes
            {
                float4 positionOS   : POSITION;
                float2 uv           : TEXCOORD0;
            };

            struct Varyings
            {
                float2 uv           : TEXCOORD0;
                float3 positionWS   : TEXCOORD1;
                float4 positionHCS  : SV_POSITION;
            };

            TEXTURE2D(_BaseMap);
            SAMPLER(sampler_BaseMap);
            
            CBUFFER_START(UnityPerMaterial)
            float4 _BaseMap_ST;
            half4 _BaseColor;
            CBUFFER_END

            Varyings vert(Attributes IN)
            {
                Varyings OUT;

                // GetVertexPositionInputs computes position in different spaces (ViewSpace, WorldSpace, Homogeneous Clip Space)
                VertexPositionInputs positionInputs = GetVertexPositionInputs(IN.positionOS.xyz);
                OUT.positionHCS = positionInputs.positionCS;
                OUT.positionWS = positionInputs.positionWS;
                OUT.uv = TRANSFORM_TEX(IN.uv, _BaseMap);
                return OUT;
            }

            half4 frag(Varyings IN) : SV_Target
            {
                // shadowCoord is position in shadow light space
                float4 shadowCoord = TransformWorldToShadowCoord(IN.positionWS);
                Light mainLight = GetMainLight(shadowCoord);
                half4 color = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, IN.uv) * _BaseColor;
                color *= mainLight.shadowAttenuation;
                return color;
            }
            ENDHLSL
        }

        // Used for rendering shadowmaps
        // TODO: there's one issue with adding this UsePass here, it won't make this shader compatible with SRP Batcher
        // as the ShadowCaster pass from Lit shader is using a different UnityPerMaterial CBUFFER. 
        // Maybe we should add a DECLARE_PASS macro that allows to user to inform the UnityPerMaterial CBUFFER to use?
        UsePass "Universal Render Pipeline/Lit/ShadowCaster"
    }
}

I'm looking forward to it after shadow pass compatible with srp.