Use of boolean switch variable toggle in shader

Description of Requirement

Check the button in the Inspector panel to act as a switch. If the button is checked, the sample map is used; if the button is not checked, the normal color is used.

Code

Shader "MyShader/ShaderToggle"
{
    
    
	Properties
	{
    
    
		[MaterialToggle(_TEX_ON)] _Toggle("Enable Main texture", Float) = 0 	//1
		_MainTex ("Texture", 2D) = "white" {
    
    }
	}
	SubShader
	{
    
    
		Tags {
    
     "RenderType"="Opaque" }
		LOD 100

		Pass
		{
    
    
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile _TEX_OFF _TEX_ON

			#include "UnityCG.cginc"

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

			struct v2f
			{
    
    
				float4 vertex : SV_POSITION;
				#if _TEX_ON
				float2 uv : TEXCOORD0;
				#endif
			};

			#if _TEX_ON
			sampler2D _MainTex;
			half4 _MainTex_ST;
			#endif
			
			v2f vert (appdata v)
			{
    
    
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				#if _TEX_ON
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				#endif
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
    
    
				fixed4 col = fixed4(1,1,0,1);
				#if _TEX_ON
				col = tex2D(_MainTex, i.uv);
				#endif
				return col;
			}
			ENDCG
		}
	}
}

be careful

1. #pragma multi_compile _TEX_OFF _TEX_ON
   Two shader versions are compiled here, one is _TEX_OFF and the other is _TEX_ON.
   _TEX_OFF does not appear in the shader code throughout, and can be understood as a shader at the bottom.
   And _TEX_ON is the shader code after the switch is turned on.

2. Also note that the code blocks of #if ... #endif use, for example:
   only when the switch _TEX_ON is turned on do we define texture coordinates and texture map reference variables:

#if _TEX_ON
float2 uv : TEXCOORD0;
#endif

#if _TEX_ON
sampler2D _MainTex;
half4 _MainTex_ST;
#endif		

_TEX_ON result checked

Uncheck _TEX_ON result