MetalRT

Ray tracing with Metal. A lab to explore various ray tracing implementations with Metal.

Usage

• Setup new app in Swift Playgrounds 4
• Delete *.swift files
• Delete predefined *.swift files in app
• Add shader.msl files with SP4 as resource
• Run app

Result

Tools

Apps used on iPad

• Swift Playgrounds 4 (SP4)
• Working Copy
• Textastic (can edit SP4 .swiftpm files)
• GitHub

Apps used on Winos 10

• Cygwin with development tools
• Swift on Windows 5.6

Setup

• Install Cygwin with development tools (for what it's good for)

• Install Swift on Windows (according to Traditional Installation section)

• Create repository on GitHub (default settings)

• Clone repository from GitHub

  Cygwin command prompt (bash)

  git clone https://github.com/otabuzzman/MetalRT
  # use SSH (optional)
  # git clone git://github.com/otabuzzman/MetalRT
  
  cd MetalRT
  

• Create SSH keys (optional)

  ssh-keygen -t ed25519 -C [email protected] -f ~/.ssh/github.com.MetalRT
  chmod 400 ~/.ssh/github.com.MetalRT
  

• Swift package initialization

  Winos command prompt (CMD)

  cd MetalRT
  
  swift package init
  
  rem check
  swift build
  

• Sync package with GitHub

  Cygwin command prompt (bash)

  # enable SSH key usage for session
  # eval "$(ssh-agent -s)"
  # ssh-add ~/.ssh/github.com.MetalRT
  
  git add -A
  git push origin main
  
  # tag required to load package with SP4
  git tag -a 0.1.0 -m 'initial commit'
  git push origin 0.1.0
  

Which file for what

Findings

• No .metal file support in SP4. Metal Shader Language (MSL) code via String class in Swift source files (e.g. ending on .metal.swift) ok for SP4 playgrounds and apps. The latter allows MSL files as resources. File suffixes must have three characters (e.g. .msl). Otherwise (e.g. when using .metal suffix) SP4 will report an unknown resource error on app open.
• Removing resource files only make them disappear in file system but app still works as if they remain present.