How to get scene depth via HLSL code.

My current code:

Code (CSharp):

1. SubShader{
2.         LOD 100
3.  
4.         Tags {
5.             "Queue" = "Transparent"
6.             "RenderType" = "Transparent"
7.             "RenderPipeline" = "UniversalPipeline"
8.             "IgnoreProjector" = "True"
9.         }
10.  
11.         ZWrite Off
12.         Blend SrcAlpha OneMinusSrcAlpha
13.  
14.         Pass {
15.             Tags {"LightMode" = "UniversalForward"}
16.  
17.             HLSLPROGRAM
18.             #pragma vertex MainVertex
19.             #pragma fragment MainFragment
20.             #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
21.             #include "MainCore.hlsl"
22.  
23.             struct Attributes {
24.                 float4 positionOS : POSITION;
25.                 float2 texCoord : TEXCOORD0;
26.             };
27.  
28.             struct Varyings {
29.                 float4 positionCS : SV_POSITION;
30.                 float2 texCoord : TEXCOORD0;
31.                 float4 screenPos : TEXCOORD1;
32.             };
33.  
34.             TEXTURE2D(_BaseMap); SAMPLER(sampler_BaseMap); float4 _BaseMap_ST;
35.  
36.             half4 _Color;
37.  
38.             Varyings MainVertex(Attributes atb) {
39.                 Varyings vriOut;
40.                 vriOut.texCoord = TRANSFORM_TEX(atb.texCoord, _BaseMap);
41.  
42.                 float3 positionWS = TransformObjectToWorld(atb.positionOS.xyz);
43.                 vriOut.positionCS = mul(UNITY_MATRIX_VP, float4(positionWS, 1));
44.                 vriOut.screenPos = ComputeScreenPos(vriOut.positionCS);
45.  
46.                 return vriOut;
47.             }
48.  
49.             half4 MainFragment(Varyings vri) : SV_Target {
50.                 float zRaw = SampleSceneDepth(vri.screenPos.xy); // this function from shader graph
51.                 float z01 = Linear01Depth(SampleSceneDepth(vri.screenPos.xy), _ZBufferParams);
52.                 float zEye = LinearEyeDepth(SampleSceneDepth(vri.screenPos.xy), _ZBufferParams);
53.                 return zRaw;
54.             }
55.             ENDHLSL
56.         }
57.     }

I don't know why it not work, please help me.

 

Hey

the problem in your code is that you forgot to map the depth in the correct uv.

first, you have to calculate the correct uv based on screenPosition, and finally use this uvs to calculate your SceneDepth:

1. 1. half4 MainFragment(Varyings vri) : SV_Target {
      
      float2 screenUVs = vri.screenPos.xy / vri.screenPos.w;
   2. float zRaw = SampleSceneDepth(screenUVs);
   3. float z01 = Linear01Depth(SampleSceneDepth(screenUVs), _ZBufferParams);
   4. float zEye = LinearEyeDepth(SampleSceneDepth(screenUVs), _ZBufferParams);
   5. return zRaw;
   6. }
      
2. hope it helps you :3