表面と裏面で描画を変えるUnityのシェーダコード 2パスで描画版とVFACEセマンティクス使った板

BackFrontAsTwoPath.shader

Shader "Unlit/TwoPasses"
{
	Properties
	{
		_FrontColor("Front Color", Color) = (1,1,1,1)
		_BackColor("Back Color", Color) = (1,1,1,1)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			Cull front
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			#pragma multi_compile_fog
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			fixed4 _FrontColor;
			fixed4 _BackColor;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 col = _FrontColor;
				return col;
			}
			ENDCG
		}

		Pass
		{
			Cull back
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
							// make fog work
			#pragma multi_compile_fog

			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			fixed4 _FrontColor;
			fixed4 _BackColor;

			v2f vert(appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				return o;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 col = _BackColor;
				return col;
			}
			ENDCG
		}
	}
}

BackFrontAsVFACE.shader

Shader "Unlit/NewUnlitShader"
{
	Properties
	{
		_FrontColor("Front Color", Color) = (1,1,1,1)
		_BackColor("Back Color", Color) = (1,1,1,1)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
		Cull off
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			#pragma multi_compile_fog
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			fixed4 _FrontColor;
			fixed4 _BackColor;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				return o;
			}
			
			fixed4 frag (v2f i, fixed facing : VFACE) : SV_Target
			{
				fixed4 col = facing > 0 ? _FrontColor : _BackColor;
				return col;
			}
			ENDCG
		}
	}
}