mobile-post-processing
Mobile Post-Processing for Unity URP
TRIGGER
Use this skill when the user wants to add, create, or optimize post-processing effects in Unity for mobile or WebGL targets. Triggers include: "post-processing", "bloom", "vignette", "color grading", "blur", "outline", "edge detection", "chromatic aberration", "Renderer Feature", "Full Screen Pass", "Blit", "post-process mobile", or any mention of screen-space effects on constrained hardware. Also trigger when the user reports post-processing is causing frame drops on mobile.
CORE RULES
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Every post-processing pass costs a full-screen blit — reading the entire framebuffer from main memory and writing it back. On tiled mobile GPUs, this flushes tile memory. Budget 0.5–2ms per pass on mid-range mobile.
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Combine all effects into a single pass whenever possible. Unity's default post-processing stack runs each effect as a separate pass. On mobile, this alone can add 6ms+ (measured: vignette alone = 6ms on some devices). Use a single-pass approach instead.
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Disable HDR unless you specifically need Bloom. HDR doubles framebuffer bandwidth (16-bit float vs 8-bit per channel). If you only need color grading, apply it in LDR.
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Bloom is the most expensive default effect on mobile. It requires downsampling, blurring, and upsampling — multiple passes. If you need it, reduce iterations (2–3 max), use a half-resolution blur, and skip the high-quality prefilter.
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Never use Motion Blur or Depth of Field on mobile. They require multiple texture samples per fragment across multiple passes.