Creating a Shading Model
This page is a current topic of research, some things may not be accurate.
AuthorAlessa "Codekitten" Baker Page StatusWIP Unreal Version5.2
Getting Started
Implementing a custom shading model in Unreal Engine can be one of the most enjoyable and rewarding experiences, because it opens up so much more opportunity to experiment in custom rendering with minimal code changes. A lot of it comes down to just replicating an existing implementation of another shading model.
Here are the files we’ll modify today.
| Files Modified | Description |
|---|---|
| EngineTypes.h | Holds most enums available in the engine that aren’t mapped to any particular class. |
| MaterialShared.cpp | |
| Material.cpp | |
| MaterialGraph.cpp | |
| SceneRenderTargets.cpp | |
| HLSLMaterialTranslator.h | |
| ShadingCommon.ush | |
| BasePassCommon.ush | |
| ShadingModelsMaterial.ush | |
| BasePassPixelShader.ush |
Prerequisites
At the time of this document being written, go ahead and git clone and then compile 5.2 branch of Unreal Engine. When you have a successful compile, we can get started by modifying our first file. If you are using an engine version ahead of this branch, I cannot guarantee you won’t have a little headache if any of these things change.
Adding our Shading Model
TODO: Adding to EngineTypes.h, and other files to inform Unreal that a new shading model exists.
Modifying the Material Editor
Enabling/Disabling Pins
TODO: MP_ and switch cases to add and modify pins
Custom Data
TODO: Describe Custom Data, and how it applies to our HLSL and is passed from the material editor as a compiled parameter.
Playing with some HLSL
TODO: Add our custom data output to Diffuse Color in Base Pass. As a quick example of passing the parameter around.
Additional Resources
[1] Shading Models Official Documentation docs.unrealengine.com
[2] New shading models and changing the GBuffer by One3y3 dev.epicgames.com.
[3] Unreal Engine 4 Rendering Part 6: Adding a new Shading Model medium.com/@lordned
[4] Implement Cel-Shading w/ Outline Using Custom Shading Model in UE4.22 (1) medium.com/@solaslin
[5] [UE4] Custom Shading Model zhuanlan.zhihu.com
[6] Porting custom UE4 shading models to UE5 (or how to tackle the new GBuffer codegen) markjg.com