Check out devices and
device fields on the wiki. (and/or watch the
yolol video on youtube)
:t6
is the name of the thruster device field that turns on a particular thruster. (it can be set anywhere from 0 to 100, as a percent of maximum thrust)
:roll
is the name of the current setting of the control lever for barrel rolls on the Vasama. (it's something like -20 to 20, since it's easy to roll a ship that tiny)
Because the lever goes both ways, it needs to activate one of two different thrusters, so you can't just rename it to match, which is why the Vasama uses some yolol chips.
So the
(:roll>0)
is a quick logic check - when it's true, it's the same thing as the number 1, when it's false, it's zero. So in the code, they multiply the yaw lever position
:yaw
by the logic, so that the when the lever is greater than 0, (when it's pushed to the right,) then the thruster will be set to that position value. (multiplied by 1) When the lever is at 0, (or pushed the other direction,) the position value is multiplied by zero, so that the thruster won't be firing.
The other half of the line is the same thing, but for the thruster on the other side - when the lever is in a negative position,
(:yaw<0)
it sets the thruster to the negative of that negative position. (to give it positive thrust)
In most ships, you just use a Flight Control Unit and a Main Flight Computer so that you don't need any control code. If you wanted, you could even skip that and still make a chip-free Vasama- just replace all the two way levers with two separate controls, one for each direction, and then you can rename each one to match its thruster and not code a thing.