C# 要将发射贴图功能添加到此着色器，我到底需要编写什么

我试图理解用代码编写的着色器，这是为统一的3D世界中的精灵而设计的着色器，它对3D照明做出反应，并具有发射贴图。稍后我将使用shader graph，但我想看看如何使用代码添加一个非常基本的发射贴图，因为我对着色器不太熟悉，也不确定在哪里写什么，我认为这将帮助我更好地理解着色器

{
    Properties
    {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        [PerRenderData] _EmissionMap("Emission Map", 2D) = "white" {}
        [HDR] _EmissionColor("Color", Color) = (1,1,1)
        _Color("Tint", Color) = (1,1,1,1)
        [MaterialToggle] PixelSnap("Pixel snap", Float) = 0
        [HideInInspector] _RendererColor("RendererColor", Color) = (1,1,1,1)
        [HideInInspector] _Flip("Flip", Vector) = (1,1,1,1)
        [PerRendererData] _AlphaTex("External Alpha", 2D) = "white" {}
        [PerRendererData] _EnableExternalAlpha("Enable External Alpha", Float) = 0
        _Cutoff("Alpha Cutoff", Range(0,1)) = 0.5
    }

        SubShader
        {
            Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
            "PreviewType" = "Plane"
            "CanUseSpriteAtlas" = "True"
        }

            Cull Off
            Lighting Off
            ZWrite Off
            Blend One OneMinusSrcAlpha

            CGPROGRAM
    #pragma surface surf Lambert vertex:vert alphatest:_Cutoff addshadow nofog nolightmap nodynlightmap keepalpha noinstancing
    #pragma multi_compile_local _ PIXELSNAP_ON
    #pragma multi_compile _ ETC1_EXTERNAL_ALPHA
    #include "UnitySprites.cginc"

            struct Input
        {
            float2 uv_MainTex;
            fixed4 color;
        };

        void vert(inout appdata_full v, out Input o)
        {
            v.vertex = UnityFlipSprite(v.vertex, _Flip);

    #if defined(PIXELSNAP_ON)
            v.vertex = UnityPixelSnap(v.vertex);
    #endif

            UNITY_INITIALIZE_OUTPUT(Input, o);
            o.color = v.color * _Color * _RendererColor;
        }

        void surf(Input IN, inout SurfaceOutput o)
        {
            fixed4 c = SampleSpriteTexture(IN.uv_MainTex) * IN.color;
            o.Albedo = c.rgb * c.a;
            o.Alpha = c.a;
            //o.Emission = 
        }
        ENDCG
        }

            Fallback "Transparent/VertexLit"
}

这是我目前的代码，我想知道我到底需要写什么，因为我一直有问题或错误，我希望这个问题可以在这里得到回答