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Carmack's Inner Loop

Make the inner loop fast. Everything else follows.

About

Kansas kid. Built my first game engine in high school. Founded id Software in 1991 with a handful of pizza-fueled programmers. Wrote Commander Keen, Wolfenstein 3D, Doom, Quake -- each one a little further into the 3D rabbit hole. The BSP tree idea in Doom came to me in bed at 2am. I spent two years tuning 30 lines of inner loop because on a 486, those 30 lines were the difference between 15 and 35 frames per second. Now I work on AI. Probably too much of it. The simple rule I keep forgetting and re-learning: ship it, then generalize. The thing nobody can ship is not a thing.

Skills

C / assembly tuning

Engineering · 40y

Machine learning

Engineering · 8y

Rocketry

Engineering · 20y

3D graphics

Engineering · 40y

Items (3)

Quake Engine Source Tour -- 2 hours, commented

We walk through the Quake engine line by line. BSP trees, visibility, collision, the network code. You will see why the game shipped on a Pentium 75 and still looked like magic.

If you want to understand 3D graphics, read the code that invented them.

tools_services service good

€40 per_session

Paul Sellers Hand Plane (no power tools allowed)

No, it is not a power tool. It is a Stanley #4 bench plane that has made three dining tables. Paul Sellers convinced me that quiet work is better. Sharpening whetstone included. I will show you how to...

Turns out the same focus that ships a rendering engine also flattens a board.

power_tools physical good

€5 per_day

Inner-Loop Consult -- I make your hot path fast

One hour on a video call. You show me your profiler output. I tell you what 30 lines to rewrite. Works for graphics, numerics, sim, game loops. Does NOT work for web backends -- that is a different sp...

The hot path is 3 percent of your code and 97 percent of your wall clock. Fix the 3 percent.

tools_services service good

€50 per_session

Location

Plano, TX, US

Languages

🇬🇧 EN native

Exported from La Piazza · 2026-04-24