Metal Migration Reference

Reference for converting OpenGL and DirectX code to Metal: shader language conversion tables, API equivalents, and setup code for MTKView, CAMetalLayer, and compute pipelines. It also covers the Metal 4 machine learning and neural rendering APIs, including the 27-release additions.

When to Use This Reference

Use this reference when:

• Converting GLSL shaders to Metal Shading Language (MSL)
• Converting HLSL shaders to MSL
• Looking up OpenGL or DirectX API equivalents in Metal
• Setting up MTKView or CAMetalLayer
• Building render or compute pipelines
• Using Apple's Metal Shader Converter for DirectX
• Integrating MetalFX denoising or upscaling into a render pipeline
• Using quantized MTLTensor types or TensorOps in shaders

Example Prompts

Questions you can ask your assistant that will draw from this reference:

• "How do I convert this GLSL shader to Metal?"
• "What's the MSL equivalent of vec4 and texture()?"
• "How do I convert HLSL semantics to Metal attributes?"
• "What does glDrawElements map to in Metal?"
• "How do I set up a Metal compute shader?"
• "What are the buffer storage modes in Metal?"
• "How do I integrate MetalFX denoising into my path tracer?"
• "What quantized MTLTensorDataType formats are available in the 27 SDKs?"
• "Can I create a three-channel RGB Metal texture without an alpha channel?"

What's Covered

• GLSL to MSL type mappings – vec4 to float4, sampler2D to texture2d + sampler, matrix types, precision qualifiers
• GLSL to MSL built-in variable mappings – gl_Position, gl_FragCoord, gl_VertexID and their MSL attribute equivalents
• GLSL to MSL function mappings – texture(), mod(), inversesqrt(), atan() and their MSL counterparts
• Complete vertex and fragment shader conversion examples – Side-by-side GLSL and MSL with struct definitions, uniform buffers, and texture sampling
• HLSL to MSL type, semantic, and function mappings – SV_Position, SV_Target, dispatch thread IDs
• Metal Shader Converter – Apple's tool for converting DXIL bytecode to Metal libraries, with workflow and options
• OpenGL API to Metal API tables – View and context setup, resource creation, state management, draw commands, primitive types
• Complete setup examples – MTKView (recommended), CAMetalLayer (custom control), compute shader pipeline
• Buffer and texture storage modes – Shared, private, and managed (macOS), with use case guidance
• Buffer alignment – Critical float3/SIMD3 alignment rules for structs shared between CPU and GPU
• Metal 4 ML and neural rendering – MetalFX denoising best practices, the machine learning command encoder, TensorOps in-shader networks, quantized tensors and MX scale formats (27 releases)
• Other 27-release Metal additions – MSL 4.1, multi-plane tensors, MetalFX content regions and frame interpolation options, persistent-kernel compute flags, forward-progress and contention-relief modes, three-channel RGB texture-buffer formats, and texture-view minLOD

Documentation Scope

This page documents the metal-migration-ref skill (in the axiom-graphics suite). It covers only the Metal side of machine learning; for model conversion, quantization, and deployment with Core ML and Core AI, see Core AI.

Related

• Metal Migration – Migration strategy, phased approach, and anti-patterns
• Metal Migration Diagnostics – Troubleshooting black screens, shader errors, and GPU crashes
• Display Performance – Frame pacing and ProMotion once your renderer runs on Metal
• RealityKit API Reference – RealityKit uses Metal under the hood

Resources

WWDC: 2016-00602, 2018-00604, 2019-00611, 2026-359, 2026-330

Docs: /metal/migrating-opengl-code-to-metal, /metalkit/mtkview, /metalfx