My name is Arseny Kapoulkine and this is my blog where I write about computer graphics, optimization, programming languages and related topics. I’m the author of pugixml, meshoptimizer and other projects.

02 September 2022 VPEXPANDB on NEON with Z3

When working on vertex compressor for meshoptimizer in 2018, one of the goals was to make a bitstream that can be decompressed using (short) SIMD vector operations. This led to a host of design decisions in terms of how the data is structured, and some challenges when mapping the decoder flow onto various SIMD architectures. The most significant issue has to do with implementing an operation that often doesn’t have a straightforward implementation: byte expansion.

08 January 2022 On Proebsting’s Law

A friend recently learned about Proebsting’s law and mentioned it to me off hand. If you aren’t aware, Proebsting’s law states:

Compiler Advances Double Computing Power Every 18 Years

Which is to say, if you upgrade your compiler every 18 years, you would expect on average your code to double in performance on the same hardware. This is in sharp contrast to Moore’s law, and suggests that we should be cautious about the performance gains that compiler evolution brings. Proebsting writes:

Perhaps this means Programming Language Research should be concentrating on something other than optimizations. Perhaps programmer productivity is a more fruitful arena.

I knew about the law’s existence but I never really asked myself - do I believe in it?

02 August 2020 Eight years at Roblox

I joined Roblox at the end of 2012 as a rendering engineer; I had just spent more than a year working on various titles from FIFA franchise after years of console game development and was becoming a bit tired of the “big game development”. My work on FIFA was as a contractor and I got an offer for a full-time position, but I also had a friend who worked at Roblox reach out and offer me to move to California and work on Roblox. I knew absolutely nothing about Roblox, but California was nice and my friend told me it would be awesome. The platform was so different (and so strange!) that I decided to take a chance - here I am, 8 years later, still working at Roblox and enjoying it. I started on my first full time job in April 2007 so at this point I’ve worked for 13 years in game development and 8 of them were at Roblox.

27 February 2020 Writing an efficient Vulkan renderer

In 2018, I wrote an article “Writing an efficient Vulkan renderer” for GPU Zen 2 book, which was published in 2019. In this article I tried to aggregate as much information about Vulkan performance as I could - instead of trying to focus on one particular aspect or application, this is trying to cover a wide range of topics, give readers an understanding of the behavior of different APIs on real hardware and provide a range of options for each problem that needs to be solved.

At the time of publishing this article, the Kindle edition of the book is available for $2.99 on Amazon - that’s cheaper than a cup of coffee and it’s definitely worth your time and money. It contains many great articles about rendering effects and design.

This, however, is the full, free of charge copy of the article - hopefully it will help graphics programmers to understand and use Vulkan to the full of its ability. The article has been lightly edited to mention Vulkan 1.1/1.2 promotions where applicable - fortunately, not much has changed in the last two years for Vulkan performance, so the content should still be mostly accurate.


22 January 2020 Learning from data

Machine learning is taking the world by storm. There’s amazing progress in many areas that were either considered intractable or had not reached a satisfying solution despite decades of research. A lot of results in machine learning are obtained using neural networks, but that’s just one class of algorithms. Today we’ll look at one key algorithm from meshoptimizer that was improved by getting the machine to find the best answer instead of me, the human1.

  1. A necessary disclaimer: I’m not a machine learning expert. It’s entirely possible that this article misuses some terms and that some analysis and conclusions here are wrong. You have been warned.