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redblobgames.com
Hi! I'm Amit Patel. I explain algorithms and math with interactive web pages (incl. pathfinding, hexagons, procgen maps, voronoi). Wrote Solar Realms Elite; helped w/Barren Realms Elite and Realm of the Mad God. https://www.redblobgames.com/
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While reviewing my mapgen4 rendering code, I realized I could render rivers in a much simpler way. The output isn't quite the same though. Left: old, right: new.

submitted 2 days ago • 4 comments

Malleable software: Restoring user agency in a world of locked-down apps www.inkandswitch.com/essay/mallea...

submitted 3 days ago • 0 comments

“I think interactive diagrams have a lot of potential -- they're not something that classrooms or books really bring to people.” —me, to a friend, in 2006

submitted 5 days ago • 0 comments

If you are in a mood for helping you can update your Dear ImGui app to `dynamic_fonts` branch this week-end and write/share all your thoughts/feedback there: github.com/ocornut/imgu... If all goes well : merge to main soon, create a new unpolluted thread for collecting feedback.

submitted 7 days ago • 1 comment

While reviewing my mapgen4 rendering code, I realized I was using 'nearest' filtering for the biome colors. What happens if I use 'linear'? (a) I get some river valleys shaded in, even where rivers have dried out (b) I get smoother colors in the oceans (added it to a list of future investigations)

submitted 7 days ago • 2 comments

While reviewing my mapgen4 geometry code, I noticed a parameter that I had hard-coded instead of exposing through sliders. I took screenshots of it at 1.00, 0.95, 0.90, 0.85, and added it to the todo list.

submitted 8 days ago • 1 comment

It's been a while since I've written about the innards of @compiler-explorer.com. xania.org/202506/how-c... has the details, some statistics and some fun war stories.

submitted 10 days ago • 2 comments

Today, working on the Delaunator guide. 1. what it looks like now - point and triangle diagrams showing a *subset* of the data 2. new version - diagrams showing *complete* data including edge cases 3. complete example, with code you can copy/paste, and numbers you can see in the diagram

submitted 13 days ago • 0 comments

I've been looking into vertical align of text. Yes, it's complicated (confusingly convoluted) as anything else in the text layout and rendering world. This is great write up on the topic (and very timely for me!) wolthera.info/2025/04/goin...

submitted 17 days ago • 0 comments

copy and paste in the terminal wizardzines.com/comics/copy-... (link to the pbcopy script: wzrd.page/pbcopy)

submitted 17 days ago • 5 comments

Wanted to compare two folders to see what files were different (unity build succeeded in one and failed in the other). Ran in bash: diff <(cd folder1; find . -type f -print0 | xargs -0 md5sum | sort) <(cd folder2; find . -type f -print0 | xargs -0 md5sum | sort) Presto, found the likely culprit.

submitted 22 days ago • 2 comments

New on the blog: "Planetfall," in which I go into great detail about making a fun map based upon a 1999 computer game. One of the most technically demanding projects of my career, for a very niche audience. somethingaboutmaps.wordpress.com/2025/05/20/p... #SMAC

submitted 23 days ago • 4 comments

Have you ever scanned a dirty or crumpled up QR code, *certain* it wouldn't work, and then it instantly does? They're built to be really resilient! Here's a guide I put together, full of interactive visuals to show the design choices in the QR spec. perthirtysix.com/how-the-heck-do-qr-codes-work

submitted 29 days ago • 1 comment

New blog post: Using flow field pathfinding on a voronoi procedurally generated map to simulate 20,000 traders moving around www.redblobgames.com/blog/2025-05...

submitted 28 days ago • 2 comments

Have you ever wished the browser would look at a background color and pick black or white for the text — whichever one provides more contrast? Now, the `constrast-color()` function in CSS does just that. webkit.org/blog/16929/c...

submitted 31 days ago • 17 comments

My survey article on line drawing algorithms, pitched for game developers jcd.pub/2025/04/10/t... #gamedev #math #geometry #lines

submitted 32 days ago • 1 comment