axiom-ios-graphics

# 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