[stella] acceleration and inertia

Subject: [stella] acceleration and inertia
From: Glenn Saunders <mos6507@xxxxxxxxxxx>
Date: Tue, 06 Jan 2004 22:27:40 -0800
Could someone explain in theoretical terms how acceleration and inertia is usually handled in 2600 games?

I was hoping to find a shortcut by "stealing" code from Indy 500, but I can't figure it out so far by reading the source, at least not enough of it to try to adapt it to Death Derby.

It seems like there are so many competing forces that it should be pretty hard to simulate cars accurately on the 2600, so I know there are a lot of shortcuts going on.

I'm pretty sure Indy500 is using a series of lookup tables and counters, but I can't figure out exactly how it works.

To accurately model the physics of a car, you'd need all these attributes:

Car Direction (intended direction [in reverse gear the direction is opposite the front of the car])
Wheel RPM (intended speed)
Direction (actual direction of motion)
Speed (actual speed)
Traction (i.e. ice)
Acceleration (i.e. time to go from speed setting to speed setting)

Indy 500 doesn't have reverse gear, but it does a fair job of the rest with very little code.

When I start thinking about modeling all these attributes I can't help but start to roll my eyes over the sheer amount of processing it will take to get to the point where I apply a change to the x and y of each car.

Any tips?

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