Unable to use normal texture in shader

[median quail]

Hello, I am relatively new to Unity, and I am trying to implement an outline scriptable render feature.

The way it would work is essentially to pass the depth and normal textures into a shader and use a Sobel filter on both to determine if an edge has to be drawn.

I am however struggling immensely when it comes to implementing this, unity just does not want to play well.

I keep getting errors like: Shader error in 'Shader Graphs/Master': redefinition of '_CameraNormalsTexture' at line 183 (on metal)

I have tried 2 different methods:

1. Make the following fullscreen shader graph

where the custom function Outline contains this hlsl code:

https://gist.github.com/kodokoto/3b8e98805f9883ccb3486e1f79fd1908

That causes these two compilation errors:

2. Create a ScriptableRenderFeature and ScriptableRenderPass, using a similar shader.

https://gist.github.com/kodokoto/ab96af3472aaecbc8403fae707aef1c1

^ Idk why this won't work, unfortunately, I am not accustomed to using the frame debugger very well yet

[quaint tundra]

The graph may already be defining _CameraNormalsTexture through an include file : DeclareDepthNormals.hlsl

Possibly _CameraDepthTexture too (through DeclareDepthTexture.hlsl), though that might only be defined when using the Scene Depth node since that one doesn't seem to be erroring.

Just removing the normals texture from the blackboard might fix it.
Though to be safer, it might be better to remove both and add those includes to your hlsl file.

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl"
#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareNormalsTexture.hlsl"

(Even if the graph is automatically including them, the #ifndef on line 1 prevents them being included multiple times)
Could even use the SampleSceneNormals/SampleSceneDepth functions inside those for sampling too.

[median quail]

Thank you so much for your reply, what you suggested makes sense. I removed the textures from the blackboard and included the files (I also used the sampling functions).

Unfortunately, this caused another error to pop up redefinition of '_Time'

Tried doing some Googling, but what I found seems to indicate that it has to do with the import overwriting some stuff maybe? I'm assuming I have to insert some sort of ifndef somewhere

[quaint tundra]

May need to wrap the includes and function contents in #ifndef SHADERGRAPH_PREVIEW. ShaderGraph has it's own ShaderLibrary includes separate from URP so you need to avoid mixing them or it causes stuff like this.

For example, I write a lot of functions intended only for URP like this

void MainLight_float (out float3 Direction, out float3 Color, out float DistanceAtten){
    #ifdef SHADERGRAPH_PREVIEW
        Direction = normalize(float3(1,1,-0.4));
        Color = float4(1,1,1,1);
        DistanceAtten = 1;
    #else
        Light mainLight = GetMainLight();
        Direction = mainLight.direction;
        Color = mainLight.color;
        DistanceAtten = mainLight.distanceAttenuation;
    #endif
}

GetMainLight() here only exists in URP so breaks within shadergraph (as it can target other pipelines). Using the SHADERGRAPH_PREVIEW avoids it erroring.