{-# LANGUAGE Arrows #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE NoMonomorphismRestriction #-} -- | Example of connecting the diagrams drawing library with Yampa. -- -- Based on: -- https://archives.haskell.org/projects.haskell.org/diagrams/gallery/VectorField.html -- -- Install diagrams with Cairo support, together with Yampa: -- -- cabal sandbox init -- cabal install Yampa diagrams -fcairo -- -- Compile in a sandbox with: -- -- cabal exec -- ghc --make examples/Diagrams.hs -- -- And run with: -- -- ./examples/Diagrams -w 400 -h 400 -o output.gif import Diagrams.Backend.Cairo.CmdLine import Diagrams.Prelude import FRP.Yampa hiding (norm, ( # ), (*^)) main = mainWith \$ take 60 frames frames :: [(Diagram B, Int)] frames = zip ((embed sfVF \$ deltaEncode 1 \$ repeat ())) (repeat 1) sfVF :: SF () (Diagram B) sfVF = proc () -> do t <- time -< () let diag = ( field t # translateY 0.05 # lc white <> ( square 3.5 # lw none # alignBL)) returnA -< diag field t = position \$ zip points (arrows t) locs = [(x, y) | x <- [0.1, 0.3 .. 3.25], y <- [0.1, 0.3 .. 3.25]] points = map p2 locs vectorField t (x, y) = r2 (sin (t + y + 1), sin (t + x + 1)) arrows t = map (arrowAtPoint t) locs arrowAtPoint t (x, y) = arrowAt' opts (p2 (x, y)) (sL *^ vf) # alignTL where vf = vectorField t (x, y) m = norm \$ vectorField t (x, y) -- Head size is a function of the length of the vector -- as are tail size and shaft length. hs = 0.02 * m sW = 0.004 * m sL = 0.05 + 0.1 * m opts = (with & arrowHead .~ spike & headLength .~ normalized hs & shaftStyle %~ lwN sW)