Tic-80: btn whithin loop freeze

[alfa33333]

When I try to use loops with a button related condition inside, the whole tic-80 freezes. I tried on the 0.80 on windows.

A simple example:

function TIC()
   testrepeat()
end

function testrepeat()
   t = 0
   flag = true
   while (flag) do
      cls()
      t = t + 1
      if btn(4) then
         flag = false
      end
      print("t"..t, 60, 60)
   end
end

It works correctly if the btn is changed for a different condition.

[StinkerB06]

It's because the gamepad/mouse/keyboard states _aren't updated in real time_. They only update after each call to TIC().

So when it enters testrepeat(), you're setting the global flag to true. Then you're running a while-loop that runs while flag is evaluated as true in Lua. Since btn(4) is always returning false, flag never gets set to false to exit the loop.

TIC-80 has nothing equivalent to PICO-8's flip() to help you out. Best option is to make testrepeat() a coroutine, then do a yield from it after the print() call. I haven't tested this myself, but maybe this will work.

[alfa33333]

Thanks, it was not obvious why gamepad/mouse/keyboard would cause such behavior, so it makes sense for the TIC 80 to actually enter an infinite loop and hang.
I imagine a note about this in the wiki would be helpful for future reference.