Read Alpha Value from uv2

Unity Engine
1

hi

i use the following shader to read alpha value from uv2 but it gives this error :

Shader "Custom/MyShader" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
	}
	SubShader {
		Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
		LOD 200
		
		CGPROGRAM
		#pragma surface surf Lambert

		sampler2D _MainTex;
		
		struct Input {
			float2 uv_MainTex;
			float2 uv2_MainTex;
		};

		void surf (Input IN, inout SurfaceOutput o) 
		{
			half4 c = tex2D (_MainTex, IN.uv_MainTex);
			half4 c2 = tex2D (_MainTex, IN.uv2_MainTex);
				
			o.Albedo = c.rgb;
			o.Alpha = c2.a;
			
		}
		ENDCG
	} 
	FallBack "Diffuse"
}
2

Apparently one texture slot may use either UV or UV2, but not both at the same time. Just create a second texture slot for your alpha value e.g. _AlphaTex.
The rendering speed will not be affected as you have to read your texture twice anyway.

3

yes it worked , thanks a lot :smile: