iOS Graphics Router
You MUST use this skill for ANY GPU rendering, graphics programming, or display performance work.
When to Use
Use this router when:
Porting OpenGL/OpenGL ES code to Metal Porting DirectX code to Metal Converting GLSL/HLSL shaders to Metal Shading Language Setting up MTKView or CAMetalLayer Debugging GPU rendering issues (black screen, wrong colors, crashes) Evaluating translation layers (MetalANGLE, MoltenVK) Optimizing GPU performance or fixing thermal throttling App stuck at 60fps on ProMotion device Configuring CADisplayLink or render loops Variable refresh rate display issues Routing Logic Metal Migration
Strategy decisions → /skill axiom-metal-migration
Translation layer vs native rewrite decision Project assessment and migration planning Anti-patterns and common mistakes Pressure scenarios for deadline resistance
API reference & conversion → /skill axiom-metal-migration-ref
GLSL → MSL shader conversion tables HLSL → MSL shader conversion tables GL/D3D API → Metal API equivalents MTKView setup, render pipelines, compute shaders Complete WWDC code examples
Diagnostics → /skill axiom-metal-migration-diag
Black screen after porting Shader compilation errors Wrong colors or coordinate systems Performance regressions Time-cost analysis per diagnostic path Display Performance
Frame rate & render loops → /skill axiom-display-performance
App stuck at 60fps on ProMotion (120Hz) device MTKView or CADisplayLink configuration Variable refresh rate optimization System caps (Low Power Mode, Limit Frame Rate, Adaptive Power) Frame budget math (8.33ms for 120Hz) Measuring actual vs reported frame rate Decision Tree User asks about GPU/graphics/Metal/display ├─ "Should I use translation layer or native?" → metal-migration ├─ "How do I migrate/port/convert?" → metal-migration ├─ "Show me the API/code/example" → metal-migration-ref ├─ "How do I set up MTKView?" → metal-migration-ref ├─ "Something's broken/wrong/slow" → metal-migration-diag ├─ "Stuck at 60fps on ProMotion" → display-performance ├─ "CADisplayLink setup/configuration" → display-performance ├─ "Variable refresh rate issues" → display-performance └─ "Frame rate not what I expect" → display-performance
Critical Patterns
metal-migration:
Translation layer (MetalANGLE) for quick demos Native Metal rewrite for production State management differences (GL stateful → Metal explicit) Coordinate system gotchas (Y-flip, NDC differences)
metal-migration-ref:
Complete shader type mappings API equivalent tables MTKView vs CAMetalLayer decision Render pipeline setup patterns
metal-migration-diag:
GPU Frame Capture workflow (2-5 min vs 30+ min guessing) Shader debugger for variable inspection Metal validation layer for API misuse Performance regression diagnosis
display-performance:
MTKView defaults to 60fps (must set preferredFramesPerSecond = 120) CADisplayLink preferredFrameRateRange for explicit rate control System caps: Low Power Mode, Limit Frame Rate, Thermal, Adaptive Power (iOS 26) 8.33ms frame budget for 120Hz UIScreen.maximumFramesPerSecond lies; CADisplayLink tells truth Example Invocations
User: "Should I use MetalANGLE or rewrite in native Metal?" → Invoke: /skill axiom-metal-migration
User: "I'm porting projectM from OpenGL ES to iOS" → Invoke: /skill axiom-metal-migration
User: "How do I convert this GLSL shader to Metal?" → Invoke: /skill axiom-metal-migration-ref
User: "Setting up MTKView for the first time" → Invoke: /skill axiom-metal-migration-ref
User: "My ported app shows a black screen" → Invoke: /skill axiom-metal-migration-diag
User: "Performance is worse after porting to Metal" → Invoke: /skill axiom-metal-migration-diag
User: "My app is stuck at 60fps on iPhone Pro" → Invoke: /skill axiom-display-performance
User: "How do I configure CADisplayLink for 120Hz?" → Invoke: /skill axiom-display-performance
User: "ProMotion not working in my Metal app" → Invoke: /skill axiom-display-performance