Re: [Haskell-cafe] threadDelay granularity

yes "get time" comes from GLFW; that is get comes from OpenGL, time from GLFW. I think the time provided by GLFW has a very high resolution but is not very accurate in the long run, which is not a real problem for games I guess On Tue, Apr 7, 2009 at 6:09 PM, Duane Johnson wrote:

The Hipmunk 2D physics engine comes with a "playground" app which includes the following function:

-- | Advances the time.

...

advanceTime :: IORef State -> Double -> KeyButtonState -> IO Double advanceTime stateVar oldTime slowKey = do newTime <- get time

-- Advance simulation let slower = if slowKey == Press then slowdown else 1 mult = frameSteps / (framePeriod * slower) framesPassed = truncate $ mult * (newTime - oldTime) simulNewTime = oldTime + toEnum framesPassed / mult advanceSimulTime stateVar $ min maxSteps framesPassed

-- Correlate with reality newTime' <- get time let diff = newTime' - simulNewTime sleepTime = ((framePeriod * slower) - diff) / slower when (sleepTime > 0) $ sleep sleepTime return simulNewTime

I think the "get time" is provided by GLFW.

-- Duane Johnson

On Apr 7, 2009, at 9:25 AM, Ulrik Rasmussen wrote:

On Tue, Apr 07, 2009 at 04:34:22PM +0200, Peter Verswyvelen wrote:

...

...

Do you want to cap the rendering framerate at 60FPS or the animation framerate? Because when you use OpenGL and GLFW, you can just

GLFW.swapInterval $= 1

to cap the rendering framerate at the refresh rate of your monitor or LCD screen (usually 60Hz)

I just want to cap the rendering framerate. The game logic is running in other threads, and sends rendering information via a Chan to the renderer.

I'm using GLUT, and have never heard of GLFW. However, that seems to be a better tool to get the job done. I'll check it out, thanks :).

/Ulrik

...

On Tue, Apr 7, 2009 at 1:41 PM, Ulrik Rasmussen wrote:

Hello.

...

I am writing a simple game in Haskell as an exercise, and in the rendering loop I want to cap the framerate to 60fps. I had planned to do this with GHC.Conc.threadDelay, but looking at it's documentation, I discovered that it can only delay the thread in time spans that are multiples of 20ms:

http://www.haskell.org/ghc/docs/6.4/html/libraries/base/Control.Concurrent.h...

I need a much finer granularity than that, so I wondered if it is possible to either get a higher resolution for threadDelay, or if there is an alternative to threadDelay?

I noticed that the SDL library includes the function "delay", which indeed works with a resolution down to one millisecond. However, since I'm using HOpenGL and GLUT, I think it would be a little overkill to depend on SDL just for this :).

Thanks,

Ulrik Rasmussen _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

_______________________________________________

Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe