Steering

[JedGrabman]

Document the steering process.

Basically, your desired steering position is set by your joystick's position. However, your steering can only change so much in one frame.

I recommend starting by reading the large comment in src/player_controller.c that explains it in more detail (before many calls to update_steering_large and update_steering_small)

Note that player->steerPosition rarely uses the rightmost 16 bits, so there's a fair amount of bit shifting.

[MegaMech]

Do you think this might technically be UB?

I wonder if it's a compiler optimization and that it might actaully be < 0

[JedGrabman]

It's strange that it's checking for 0xF... instead of 0x8... If it was compiler checking for < 0, I would expect it to only be checking the first bit for the sign. I'll admit I missed that initially. But it's a detail that makes me think it was coded by a human instead of a compiler.

I think that leads to a theoretical bug. A negative number with a large enough magnitude fails the comparison when I run it on an online c compiler, presumably because the two's complement actually makes it smaller when interpreted as an unsigned int. But, that bug can't actually come into play because steerChangeIncrement only changes by 2**11 at a time.

I'm not an expert on undefined behavior, but the wikipedia article on it uses underflows in C as an example, so I suppose it is.