UnityShaderBook/Assets/Shaders/Extra/TestFogShader.shader

Shader "Unlit/TestFogShader"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_FogAlpha("Fog Alpha",Range(0.0,1.0))= 1.0
		_FogColor("Fog Color",COLOR) = (1,1,1,1)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" "Queue"="Transparent" }
		LOD 100

		Pass
		{
			Cull Off
			ZWrite Off
			Blend SrcAlpha OneMinusSrcAlpha
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

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

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 srcVertex : TEXCOORD1;
				float4 scrPos : TEXCOORD2;
				float4 vertex : SV_POSITION;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _FogAlpha;
			fixed4 _FogColor;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.srcVertex = v.vertex;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.scrPos = ComputeScreenPos(o.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				// sample the texture
				fixed4 col = tex2D(_MainTex, i.uv);
				fixed4 colAlpha = fixed4(col.rgb,clamp(col.a*abs(i.scrPos.y),0.0,1.0));
				return colAlpha*_FogAlpha*_FogColor;
			}
			ENDCG
		}
	}
}