Stage specific shader keywords (GLES, Vulkan)
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Summary
The amount of produced shader variants grow exponentially based on keywords usage, and can lead to:
- Increased build times due to processing and compilation of variants.
- Increased filesize, memory usage and shader loading time due to an increased amount of included shaders.
By default, Unity generates keyword variants for each stage of your shader. If a set of keywords is only used in one of those stages, this results in identical variants for the other stage. Unity automatically identifies and deduplicates identical variants so that they do not increase build size, but they still result in wasted compilation time, increased shader loading times, and increased runtime memory usage.
To avoid this problem, when you declare a set of keywords in a hand-coded shader, you can instruct Unity to compile them only for a given shader stage. You are then responsible for ensuring that the keywords are only used in the specified shader stages.
However, stage specific keywords are currently unsupported when targeting OpenGL and Vulkan platforms.
Intended Behavior/Usecase
- Stage specific shader keywords are supported when targeting the GLES and Vulkan backends.