Source{- Module : Main
Copyright : BSD License
License :
Maintainer : Berlin Brown
Stability :
Portability :
Description : Strict Annotation Example
Define a Camera type with pos vectors and then
print the data.
Also see the following article on
strictness annotations to data and functions
http://users.aber.ac.uk/afc/stricthaskell.html#seq
Eg,
data Shape = Circle !Int !Int !Colour | Square !Int !Colour
-}
import Data.IORef
data Camera = Camera {
cameraPos :: !(Float, Float, Float),
cameraAngle :: !(Float, Float, Float),
cameraRot :: !(Float, Float, Float),
cameraCenterAxis :: !(Float, Float, Float),
cameraYaw :: !(Float, Float, Float),
cameraPitch :: !(Float, Float, Float),
cameraRoll :: !(Float, Float, Float)
} deriving (Read)
{- These 'Show' instances can be converted to character strings
for pretty printing the information the data type contains.
Also see the following for more information types
(eg, to reference their field names, etc)
http://www.haskell.org/tutorial/moretypes.html
-}
instance Show Camera where
show defCamera = "<Camera> (x, y, z) =[" ++
show (cameraPos defCamera)
-- Initialize a camera
-- Only set the camera position, camera angle and rotation
-- (Position, Camera Angle, Camera Rotation)
initCamera :: (Real posv) => (posv, posv, posv)-> (posv, posv, posv) -> (posv, posv, posv) -> Camera
initCamera (x1, y1, z1) (x2, y2, z2) (x3, y3, z3) =
Camera {
cameraPos = ((realToFrac x1), (realToFrac y1), (realToFrac z1)),
cameraAngle = ((realToFrac x2), (realToFrac y2), (realToFrac z2)),
cameraRot = ((realToFrac x3), (realToFrac y3), (realToFrac z3)),
cameraCenterAxis = (0, 0, 0),
cameraYaw = (0, 0, 0),
cameraPitch = (0, 0, 0),
cameraRoll = (0, 0, 0) }
main :: IO ()
main = do
putStrLn "Running Test"
let mainCamera = initCamera (0, 0.7, 0) (0,0,0) (0,0,0)
mainCameraRef <- newIORef(mainCamera)
mainCameraShowReadRef <- readIORef mainCameraRef
putStrLn $ "==>" ++ show mainCamera
putStrLn $ "==>" ++ show mainCameraShowReadRef
{- Test to override the existing camera and print the data -}
let mainCameraAnother = initCamera (0.2, 0.3, 4) (0,0,0) (0,0,0)
writeIORef mainCameraRef mainCameraAnother
mainCameraShowReadRef <- readIORef mainCameraRef
putStrLn $ "==>" ++ show mainCameraShowReadRef
putStrLn "Done"
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