Shader Alpha Cutout

My app currently uses multiple shaders based on users selection. I wanted to add a feature to each shader that will cutout parts of the object based on an alpha image.

In my shader below, you'll notice I have a separate pass in the end of the cutout, this is basically adding the image on top of the model over the existing color, I want to have it cutout instead of actually drawing the image over the material. I would even settle with having the reverse effect where the alpha portion would be where it shows the original material.

Code (CSharp):

1.  
2. Shader "Opaque Reflective"
3. {
4.     Properties
5.     {
6.         _BaseColor("Base Color", Color) = (1.0, 1.0, 1.0, 1.0)
7.         _DetailColor("Detail Color", Color) = (1.0, 1.0, 1.0, 1.0)
8.         _DetailMap("Detail Map", 2D) = "white" {}
9.         _DetailMapDepthBias("Detail Map Depth Bias", Float) = 1.0
10.         _DiffuseColor("Diffuse Color", Color) = (1.0, 1.0, 1.0, 1.0)
11.         _DiffuseMap("Diffuse Map", 2D) = "white" {}
12.         _Cutout("Cutout", 2D) = "" {}
13.         _NormalMap("Normal Map", 2D) = "bump" {}
14.         _ReflectionColor("Reflection Color", Color) = (1.0, 1.0, 1.0, 1.0)
15.         _ReflectionMap("Reflection Map", Cube) = "" {}
16.         _ReflectionStrength("Reflection Strength", Range(0.0, 1.0)) = 0.5
17.     }
18.  
19.     SubShader
20.     {
21.         Tags
22.         {
23.             "Queue" = "Geometry"
24.             "RenderType" = "Opaque"
25.         }
26.  
27.         Blend Off
28.         Cull Back
29.         ZWrite On
30.  
31.         CGPROGRAM
32.         #pragma target 3.0
33.         #pragma surface SurfaceMain Lambert vertex:VertexMain
34.  
35.         float4 _BaseColor;
36.         float4 _DetailColor;
37.         sampler2D _DetailMap;
38.         float _DetailMapDepthBias;
39.         float4 _DiffuseColor;
40.         sampler2D _DiffuseMap;
41.         sampler2D _Cutout;
42.         sampler2D _NormalMap;
43.         float4 _ReflectionColor;
44.         samplerCUBE _ReflectionMap;
45.         float _ReflectionStrength;
46.  
47.         struct Input
48.         {
49.             float depth;
50.             float2 uv_DetailMap;
51.             float2 uv_DiffuseMap;
52.             float2 uv_NormalMap;
53.             float3 worldRefl;
54.             INTERNAL_DATA
55.         };
56.  
57.         void SurfaceMain(Input input, inout SurfaceOutput output)
58.         {
59.             output.Normal = UnpackNormal(tex2D(_NormalMap, input.uv_NormalMap));
60.  
61.             float3 reflectionColor = texCUBE(_ReflectionMap, WorldReflectionVector(input, output.Normal)).rgb * _ReflectionColor.rgb;
62.             float4 diffuseColor = tex2D(_DiffuseMap, input.uv_DiffuseMap) * _DiffuseColor;
63.             float3 finalColor = lerp(lerp(_BaseColor.rgb, diffuseColor.rgb, diffuseColor.a), reflectionColor, _ReflectionStrength);
64.  
65.             float3 detailMask = tex2D(_DetailMap, input.uv_DetailMap).rgb;
66.             float3 detailColor = lerp(_DetailColor.rgb, finalColor, detailMask);
67.             finalColor = lerp(detailColor, finalColor, saturate(input.depth * _DetailMapDepthBias));
68.  
69.             output.Albedo = finalColor;
70.             output.Alpha = _BaseColor.a;
71.         }
72.  
73.         void VertexMain(inout appdata_full input, out Input output)
74.         {
75.             UNITY_INITIALIZE_OUTPUT(Input, output);
76.             output.depth = UnityObjectToClipPos(input.vertex).z;
77.         }
78.         ENDCG
79.          
80.             Pass{
81.             Name "Cutout"
82.             AlphaTest Greater 0.9
83.             SetTexture[_Cutout]{
84.  
85.         }
86.         }
87.     }
88.  
89.     FallBack "VertexLit"
90. }
91.  

 

You don't need another pass for this. Just set your alpha texture and clip directly in the first pass.

 

The problem is I am new to shaders and wouldn't even know where to start. I have added a pass before to add a decal, but this is different.

 

Look for alphatest in the surface shader documentation.

https://docs.unity3d.com/Manual/SL-SurfaceShaders.html

 

Thanks, I found a Unity answers post that helped me:
http://answers.unity3d.com/questions/244837/shader-help-adding-transparency-to-a-shader.html

 

How can I do this with URP?

 

Blend One Zero
AlphaToMask On