Porting a Toy Path Tracer to Swift

I ported a toy path tracer to Swift.

Some performance numbers:

  • Colab, effectively single threaded: 3 Mrays/s
  • iPhone 11 Pro Max: 18 Mrays/s
  • iPad Pro 12.9" 2018: 21 Mrays/s
  • iMac Pro 2017 18-core: 96 Mrays/s
The hardest part of the port was reducing contention between threads. I had to replicate the tracing object (which contains the scene data) per thread in order to avoid serializing on ARC retain/release code.

Swift currently has no way to share an immutable object graph across multiple threads without incurring ARC overhead every time any object in that graph is accessed.

Perhaps when Swift implements some form of the Ownership Manifesto this will be fixed.


Comments

Post a Comment

Popular posts from this blog

GLES Quake - a port of Quake to the Android platform

I've just published the source code to a port of Quake to the Android platform . This is something I did a while ago as a internal test application. It's not very useful as a game, because there hasn't been any attempt to optimize the controls for the mobile phone. It's also awkward to install because the end user has to supply the Quake data files on their own. Still, I thought people might enjoy seeing a full-sized example of how to write a native code video game for the Android platform. So there it is, in all its retro glory. (Porting Quake II or Quake III is left as an exercise for the reader. :-) What's different about this particular port of Quake? Converted the original application into a DLL Android applications are written in Java, but they are allowed to call native languge DLLs, and the native language DLLs are allowed to call a limited selection of OS APIs, which include OpenGL ES and Linux File I/O. I was able to make the game work by using Java for: T...
Read more

A Taipei-Torrent postmortem: Writing a BitTorrent client in Go

This is a BitTorrent client. There are many like it, but this one is mine. -- the BitTorrent Implementer's Creed For fun I've started writing a command-line BitTorrent client in Google's go programming language. The program, Taipei-Torrent , is about 70% done. It can successfully download a torrent, but there are still lots of edge cases to implement. Go routines and channels are a good base for writing multithreaded network code. My design uses goroutines as follows: a single main goroutine contains most of the BitTorrent client logic. each BitTorrent peer is serviced by two goroutines: one to read data from the peer, the other to write data to the peer. a goroutine is used to communicate with the tracker some "time.Tick" goroutines are used to wake the main goroutine up periodically to perform housekeeping duties. All the complicated data structures are owned by the main goroutine. The other goroutines just perform potentially blocking network I/O using channel...
Read more

Writing an Android application in JavaScript and HTML5

Image
Happy Mother's Day everyone! This year I wrote an Android app for my wife for Mother's Day. How geeky is that? The reason I wrote it is that my wife's favorite Android application, Word Mix Lite, recently added annoying banner ads. While the sensible thing to do might have been to switch to another app, or perhaps upgrade to the paid version of Word Mix, I thought it might be interesting to see if I could write my own replacement. And as long as I was writing the app, I though I'd try writing it using JavaScript. Normally Android applications are written in Java, but it's also possible to write them in JavaScript, by using a shell application such as PhoneGap . Why use JavaScript instead of Java? Well, hack value mostly. On the plus side it's a fun to write! Another potential plus is that it is theoretically possible to run the same PhoneGap application on both Android and Apple. The drawback is that PhoneGap is not very popular yet, especially among Android dev...
Read more