freeze simulation in gloss Haskell

Question

I'm using the gloss library to picture a simulation. Is there a function, which stops the simulation function when a condition is true. Just the last drawn picture should remain in the window.

Thanks in advance

What about just adding another state variable to record whether or not the simulation should be frozen? If the `isFrozen` value is `True` you just return the current model; otherwise you evolve it - i.e. apply the step function. — ErikR, Sep 04 '16 at 14:10

score 0 · Answer 1 · answered Sep 05 '16 at 08:31

As @ErikR suggested, what you're describing amounts to not updating the model anymore once you've reached the state you are looking for. You can define a combinator acting on stepping functions doing precisely this:

untilModel
  :: (ViewPort -> Float -> model -> model)
  -> (model -> Bool)
  -> (ViewPort -> Float -> model -> model)
untilModel step isFrozen v f m =
  if isFrozen m then m
  else step v f m

When you have a step function and you want to stop the simulation when isFrozen becomes true of the model, you can simply pass simulate the altered step function step `untilModel` isFrozen.

freeze simulation in gloss Haskell

1 Answers1