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Arseny Kapoulkine (email, 
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Arseny Kapoulkine (email, , )
Work, projects and publications
If you like this blog, you should follow it via RSS and read older posts. Here are the recent posts:
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, volk and other projects.
Hardware accelerated raytracing, as supported by DirectX 12 and Vulkan, relies on an abstract data structure that stores scene geometry, known as “acceleration structure” and often referred to as “BVH” or “BLAS”. Unlike geometry representation for rasterization, rendering engines can not customize the data layout; unlike texture formats, the layout is not standardized across vendors.
It may seem like a trivial matter - surely, by 2025 all implementations are close to each other in memory consumption, and the main competition is over ray traversal performance and new ray tracing features? Let’s find out.
I am happy to report that life after Roblox does indeed exist.
When I quit, people told me I should take some time off, relax, unwind, recharge, travel…
The first somewhat social platform that I’ve used was LiveJournal; I used it around 2004-2010. Back then, we had posts and comments, but one of the notable features of the platform was the uni-directional friend relationships. The number of people who befriended you was somewhat of a status symbol, with a special term “тысячник” (a person with 1000+ reverse friend connections) used to denote Popular People.
That said, my recollection is that people mostly wrote what was fun or interesting for them to write about. Your friend feed contained a chronological display of whatever your friends posted - no ads, no algorithms.
I regularly hear or read statements like this: “X is slow but this is to be expected because it needs to do a lot of work”. It can be said about an application or a component in a larger system, and can refer to other resources that aren’t time. I often find these profoundly unhelpful as they depend much more on the speaker’s intuition and understanding of the problem, than X itself.
In Luau, modulo operator a % b is defined as a - floor(a / b) * b, the definition inherited from Lua 5.1. While it has some numeric issues, like behavior for b = inf, it’s decently fast to compute so we have not explored alternatives yet.
That is, it would be decently fast to compute if floor was fast.