45 lines
2.0 KiB
Markdown
45 lines
2.0 KiB
Markdown
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# Synchronizing shader code and C#
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Unity can generate HLSL code based on C# structs to synchronize data and constants between shaders and C#. In Unity, the process of generating the HLSL code from C# code is called generating shader includes. When Unity generates shader includes, it parses all the C# files in the project and, for every file that contains a struct with a GenerateHLSL attribute, generates corresponding HLSL code. It places this HLSL code in a file with the same name as the origin, but uses the `.cs.hlsl` file extension.
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## Generating shader includes
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To generate an HLSL equivalent for a C# struct:
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1. Add the GenerateHLSL attribute to the struct. To do this, above the line that declares the struct, add `[GenerateHLSL(PackingRules.Exact, false)]`. For an example on how to do this, see the sample code below. For more information about the GenerateHLSL attribute, see the [API documentation](../api/UnityEngine.Rendering.GenerateHLSL.html).
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2. In the Unity Editor, go to **Edit** > **Render Pipeline** > **Generate Shader Includes**.
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The following code example is from the High Definition Render Pipeline (HDRP). It shows an extract of the C# representation of a directional light. The original file is `LightDefinition.cs`. When Unity generates the HLSL shader code, it places it in a new file called `LightDefinition.cs.hlsl`.
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```
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// LightDefinition.cs
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[GenerateHLSL(PackingRules.Exact, false)]
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struct DirectionalLightData
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{
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public Vector3 positionRWS;
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public uint lightLayers;
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public float lightDimmer;
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public float volumetricLightDimmer; // Replaces 'lightDimer'
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public Vector3 forward;
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public Vector4 surfaceTextureScaleOffset;
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};
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```
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```
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// LightDefinition.cs.hlsl
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// Generated from UnityEngine.Rendering.HighDefinition.DirectionalLightData
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// PackingRules = Exact
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struct DirectionalLightData
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{
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float3 positionRWS;
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uint lightLayers;
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float lightDimmer;
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float volumetricLightDimmer;
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float3 forward;
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float4 surfaceTextureScaleOffset;
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};
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```
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