Every time you build your project, the Unity Editor compiles all the shaders that your build requires: every required shader variant, for every required graphics API.
When you’re working in the Unity Editor, the Editor does not compile everything upfront. This is because compiling every variant for every graphics API can take a very long time.
Instead, Unity Editor does this:
Shader compilation is carried out using a process called
UnityShaderCompiler processes can be started (generally one per CPU core in your machine), so that at player build time shader compilation can be done in parallel. While the Editor is not compiling shaders, the compiler processes do nothing and do not consume computer resources.
The shader cache folder can become quite large, if you have a lot of shaders that are changed often. It is safe to delete this folder; it just causes Unity to recompile the shader variants.
At player build time, all the “not yet compiled” shader variants are compiled, so that they are in the game data even if the editor did not happen to use them.
You can use predefined shader macros to identify which compiler Unity is using. You might want to use this if you use HLSL syntax that is supported by only one compiler, or to work around a compiler bug.
You can configure various shader compiler settings using pragma directives.
Shader compilation involves several steps. One of the first steps is preprocessing the shader source. By default, Unity uses the platform compiler’s preprocessor to perform this step; however, you can choose to override this and use Unity’s Caching Shader Preprocessor to perform preprocesing. The Caching Shader Preprocessor is up to 25% faster than the default preprocessors used by platform compilers.
The Caching Shader Preprocessor caches intermediate preprocessing data to speed up shader import and compilation time. The Editor reuses this cached data, and only needs to parse include files when their contents change. This makes compiling multiple variants of the same shader more efficient. Enabling the Caching Shader Preprocessor has the most noticeable effect when shaders within a project use a large set of common include files.
Note that the Caching Shader Preprocessor is experimental; it is still in active development. You can provide feedback on this experimental feature in the Unity forum.
You can enable or disable the Caching Shader Preprocessor using the Caching Shader Preprocessor checkbox in the Shader Compilation section of the Editor settings window. You can also enable or disable this feature in a C# script, using the EditorSettings.cachingShaderPreprocessor API.
#pragma shader_feature的着色器，Unity 会自动检查是否使用了变体。如果构建中的材质都不使用某个变体，则该变体不会包含在构建中。请参阅内部着色器变体文档。标准着色器会使用此功能。