[EU] The shader compiler

Because the engine uses the Vulkan API, we are required to precompile the shader files to a bytecode intermediate format. This format is called SPIR-V. We use the UVKShaderCompiler as a CLI tool/library to handle compilation and recompilation of shaders.

The UVKShaderCompiler can either be invoked by the game engine at runtime when changes to the shaders are found, or by using the UVKShaderCompiler executable.

How it works

The UVKShaderCompiler scans the Config folder of your project for shader files, next it generates the MD5 hash of the file and scans the Generated directory for any file with that exact hash as a filename. If no file is found, the shaders get recompiled, otherwise it continues on to the next shader in the Content directory.

In production because those hashes are not needed for validating the shaders, the shaders get compiled into the Content directory with the original name of the source code file. Then, they get packaged by the archive and shipped. If any tampering happened in the archive, the developer can check using the entire archive's hash.

Using the CLI

Since the UVKShaderCompiler provides a CLI interface, you can use it for manual compilation. There are 3 options

1. --help <directory to project> - for help
2. --complete-regen <directory to project> - for completely regenerating the cache
3. --compile <directory to project> - for compiling the cache

Shader formats

The shader compiler can get the following shader formats as input:

1. .frag - fragment shader
2. .vert - vertex shader
3. .comp - compute shader
4. .geom - geometry shader
5. .tesc - tessellation control shader
6. .tese - tessellation evaluation shader

All you need to do is create a file with the given file extension in the Content/ directory, and it will automatically be compiled!