I have a program which simulates the interaction of many agents in a community. I'm animating the interaction using the Gloss library, the pictures of the agents render correctly, just not the animation. I animate it by generating a simulation, which is a list of list of interactions, which I then take the one corresponding to the second of the animation, where I then render that interaction. The code for simulating works fine when outputting it to terminal. The code:
render :: Int -> History -> Picture -- assume window to be square
render size (History int agents) = Pictures $ map (drawAgent (step`div`2) colors step) agents
where step = size*6 `div` (length agents)
--agents = nub $ concat $ map (\(Interaction a1 a2 _ ) -> [a1,a2]) int
nubNames = nub $ map (getName . name) agents --ignore the first two letters of name
colors = Map.fromList $ zipWith (\name color-> (name, color)) nubNames (cycle colorlist)
colorlist = [red,green,blue,yellow,cyan,magenta,rose,violet,azure,aquamarine,chartreuse,orange]
drawAgent :: Int -> Map.Map String Color -> Int -> Agent -> Picture
drawAgent size colors step agent =
color aColor (Polygon [(posA,posB),(posA,negB),(negA,negB),(negA,posB)])
where aColor = fromMaybe black $ Map.lookup (getName $ name agent ) colors
a = (fst $ position agent) * step
b = (snd $ position agent) * step
posA = fromIntegral $ a+size
negA = fromIntegral $ a-size
posB = fromIntegral $ b+size
negB = fromIntegral $ b-size
simulate :: Int -> [Agent] -> [History]
simulate len agents = trace ("simulation"
(playRound agents len) :
simulate len (reproduce (playRound agents len))
main = do
a <- getStdGen
G.animate (G.InWindow "My Window" (400, 400) (0,0)) G.white
(\time ->(render 400) $ ((simulate 5 (agent a))!!(floor time)))
where agent a = generate a 9
sim a = simulate 40 (agent a)
When I execute this, it will say the simulation is running, but only render the first interaction.
$ ghc -O2 -threaded main.hs && ./main
[6 of 8] Compiling Prisoners ( Prisoners.hs, Prisoners.o )
Linking main ...
simulation
simulation
simulation
It will continue like this until I stop it, rendering the same picture each time. What am I doing wrong?