The 2D physics prototype that became GTA's vehicle system
2D Vehicles
In 1996, Pat Kerr wrote a wireframe 2D rigid-body simulation on an Atari ST in GFA BASIC that later powered the vehicles in Grand Theft Auto. For its 30th anniversary, he has recreated it in JavaScript as Motion Lab, where you can drive a Car, Ship, or Brick and toggle barriers, gravity, and camera behaviors. The prototype combined proper torque physics with a deliberately approximate tyre model—a semi-educated guess that felt good enough.
It was basically a semi-educated guess on my part and, although I knew it wasn't really physically accurate, it nevertheless seemed to be 'good enough' for my purposes at the time.
- zeroq
When mentioning foundational 2d driving models one simply can't omit Marco Monster (2003) [1].
Also Physics for Game Developers (2001) had a hilarious chapter dedicated to car racing simulation. Most of the chapter is dedicated building the scene in a minute detail - for instance pointing out that the center of gravity of the car will change during the course due to fuel consumption - only to simplify and cancel out most things at the end to leave the reader with just a handful of variables.
[1] https://www.asawicki.info/Mirror/Car%20Physics%20for%20Games...
- matsemann
I'm sorry, I really want to like and understand this, but the diagrams are worthless and mostly incomprehensible.
I would've liked to understand more about why it works the way it does, how it achieved the correct feel etc, not just regurgitate whatever the code does.
I would've liked to know more about how the author achieved what they did, not a blog post anyone with an llm could've written.
- wongarsu
GTA I and II had really fun car physics. Just driving around and evading police was fun, in a way the later 3d games in the series didn't quite capture for me
- slowin
It still feels great to play! I love the history too, it's actually a great example of why prototyping "toys" is so important in product development. It allows you to play with isolated concepts without baggage or the expectation to make things production grade. Just getting straight to the point.
Great story, programming and mechanics.
- plasticeagle
I wrote a 2D car physics engine, using Verlet integration. Unfortunately, I wrote it in ActionScript instead of something sensible.
It did work great though.
- joshu
no dynamics model (uses bicycle model) but i built a solver for parking
- londons_explore
This is what taught me how to do handbrake turns.
And shortly after I learned how expensive tyres were, I stopped doing handbrake turns.
- ionwake
To the creator, thank you. I spent many years almost 2 decades alter playing multiplayer gta2 with my good friend during late night sessions.
Thank you for a great little physics engine