A Random Walk Through Geek-Space

Brain dumps and other ramblings from Sebastian Sylvan

Fixing Texture Seams With Linear Least-Squares

16/Nov 2015 17 min. read

This post is about how use least squares optimization to slightly adjust the texel values in a texture in order to minimize seams across edges in UV-space.

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Moving off of WordPress!

4/Nov 2015 2 min. read

Whenever I would write blog posts on WordPress a huge source of friction was just how shitty the editing experience was. You could write the post elsewhere and then try to upload it but I found I was frequently surprised by things not looking quite right once WordPress was through with it. The online post editing tool was also an exercise in extreme frustration. So I decided to simplify my life a bit.
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Brackets are awesome, don’t use them!

21/May 2015 4 min. read

This is a syntax bike-shedding post, where I will try to explain why I think languages should stop using curly brackets for code blocks. I don’t expect anyone to come away completely blown away by this or anything, but I’m a language nerd and often end up discussing in-development languages with their designers. And since approximately 90% of all language discussion is about syntax, I’ll just write a reusable note on brackets here.
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Why (most) High Level Languages are Slow

13/Apr 2015 12 min. read

programming languages software engineering

In the last month or two I’ve had basically the same conversation half a dozen times, both online and in real life, so I figured I’d just write up a blog post that I can refer to in the future. The reason most high level languages are slow is usually because of two reasons: They don’t play well with the cache. They have to do expensive garbage collections But really, both of these boil down to a single reason: the language heavily encourages too many allocations.
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Variable Refresh Monitors and Animation

24/Jan 2015 6 min. read

So variable refresh rates have a lot of hype surrounding them now, with representatives from GPU and monitor vendors are saying that it will just magically make existing games better with no effort required on the part of the developer. This is bullshit and you shouldn’t believe them. If you’re a developer you need to be careful to handle these new refresh rates and if you’re a customer you should consider just locking your monitor to 60Hz for games that don’t do the right thing.
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Flags are a code smell

27/Apr 2014 8 min. read

In most major code bases, it’s common to have objects with lots of Boolean flags indicating what state they’re in. E.g. is an enemy targeting the player or not? Is it trying to flee or not? If you have a set of mutually exclusive flags an enum can be used instead, but this is often not possible, and doesn’t change much in terms of the downsides. In my opinion these are code smells.
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The Perils of Future-Coding

16/Aug 2013 14 min. read

In my opinion, one of the most insidious form of technical debt is what I like to call future-coding. You might also call it over-engineering, second-system syndrome, etc. It’s code written in an overly elaborate and general way in order to, the future-coder reasons, pre-emptively handle use cases that we’ll “probably see in the future”. I find it more treacherous than plain “stupid code” because it predominantly affects smart people.
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More on Robin Hood Hashing

5/Aug 2013 4 min. read

I posted about Robin Hood hashing in a previous post. In the comments to that post David Wragg pointed out a flaw in my implementation: if you repeatedly delete and reinsert elements into a hashtable, the average probe count keeps rising. This is a good observation, and it’s true. Repeatedly deleting items makes the table slower but it (until you insert enough to trigger a rebuild of the table, which will filter out any tombstones - note: the number tombstones do not affect the rate of rebuilds).
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Language Design Deal Breakers

25/May 2013 9 min. read

I’m a bit of a programming language nerd. I love to learn new languages. That said, I spend most of my days writing C++. It’s a truly awful language, with many warts and problems, but I know it well and with enough effort and pain you can get the job done. The biggest benefit of C++ is purely an historical accident: it’s great because it’s popular. There’s no trouble finding people who know it, or libraries that work with it.
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Robin Hood Hashing should be your default Hash Table implementation

8/May 2013 9 min. read

There’s a neat variation on open-addressing based hash tables called Robin Hood hashing. This technique isn’t very well-known, but it makes a huge practical difference because it both improves performance and space utilization compared to other “standard” hash tables (e.g. chaining). It also eliminates the major downside of other open addressing hash tables. Here are the benefits, summarized: High load factors can be used without seriously affecting performance. 0.
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