Опишем в Hipmunk модель шарика бегающего в замкнутой коробке:
module Main where
import Data.StateVar
import Physics.Hipmunk
main = do
initChipmunk
space <- newSpace
initWalls space
ball <- initBall space initPos initVel
loop 100 space ball
loop :: Int -> Space -> Body -> IO ()
loop 0 _
_
= return ()
loop n space ball = do
showPosition ball
step space 0.5
loop (n-1) space ball
showPosition :: Body -> IO ()
showPosition ball = do
pos <- get $ position ball
print pos
initWalls :: Space -> IO ()
initWalls space = mapM_ (uncurry $ initWall space) wallPoints
initWall :: Space -> Position -> Position -> IO ()
initWall space a b = do
body
<- newBody infinity infinity
shape
<- newShape body (LineSegment a b wallThickness) 0
elasticity shape $= nearOne
spaceAdd space body
spaceAdd space shape
initBall :: Space -> Position -> Velocity -> IO Body
initBall space pos vel = do
body
<- newBody ballMass ballMoment
shape
<- newShape body (Circle ballRadius) 0
Основные библиотеки | 295
position body $= pos
velocity body $= vel
elasticity shape $= nearOne
spaceAdd space body
spaceAdd space shape
return body
----------------------------
-- inits
nearOne = 0.9999