03. Basic Ship Movement
In this step, we will add code to move the ship around the screen.
At the end of the _update function, add an if statement for each arrow key.
Tip: After typing the first if statement, hit ctrl-d to duplicate the
first line. Then edit the new line. This will save you some typing.
if btn(L) then ship.x-=1 end
if btn(R) then ship.x+=1 end
if btn(U) then ship.y-=1 end
if btn(D) then ship.y+=1 end
On each frame, _update new checks to see if an arrow key is being held down.
If it is, it changes the pixel coordinate of the ship by 1 in the appropriate
direction.
Hit ctrl-r to run your cart and try it out!