Use system sleep functions as threadDelay sleep to long without -threaded

src/HTanks.hs

@@ -21,6 +21,9 @@ import qualified Data.Map as M
 import qualified Data.Set as S
 import Data.Time
 
+import Foreign.C.Types
+
+
 main :: IO ()
 main = do
   let theLevel = testLevel
@@ -45,7 +48,7 @@ main = do
          deinitGL gl
 
 minFrameTime :: NominalDiffTime
-minFrameTime = 0.01
+minFrameTime = 0.02
 
 mainLoop :: Main ()
 mainLoop = do
@@ -60,9 +63,10 @@ mainLoop = do
   rtime <- liftIO getCurrentTime
   let drender = diffUTCTime rtime t
   when (drender < minFrameTime) $
-       liftIO $ threadDelay $ truncate $ 1e6*(minFrameTime - drender)
+       liftIO $ usleep gl $ truncate $ 1e6*(minFrameTime - drender)
   
   currenttime <- liftIO getCurrentTime
+  liftIO $ print $ diffUTCTime currenttime rtime
   let d = round $ 1e2*(diffUTCTime currenttime t)
   
   replicateM_ d simulationStep
@@ -74,7 +78,6 @@ mainLoop = do
   runnext <- gets run
   when runnext mainLoop
 
-
 handleEvents :: Main ()
 handleEvents = do
   (newgl, event) <- gets driver >>= liftIO . nextEvent