Fix use of ddt.

1 files changed, 7 insertions, 4 deletions

diff --git a/Spear/App.hs b/Spear/App.hs
index 93837c2..7f23359 100644
--- a/Spear/App.hs
+++ b/Spear/App.hs
@@ -32,7 +32,7 @@ data AppOptions = AppOptions
   }
 
 defaultAppOptions = AppOptions
-  { maxFPS          = 60 -- If non-zero, cap frame rate to this value.
+  { maxFPS          = 0  -- If non-zero, cap frame rate to this value.
   , animationFPS    = 60 -- If non-zero, use fixed time step animation.
   , enableProfiling = False
   }
@@ -69,13 +69,13 @@ loop app window = do
 
 loop' ::
   Window ->
-  TimeDelta -> -- Desired frame time delta.
+  TimeDelta -> -- Desired render time delta.
   TimeDelta -> -- Desired animation time delta.
   TimePoint -> -- Time point of last animation update.
   Timer ->
   App s ->
   Game s ()
-loop' window ddt animationDdt lastAnimationTime inputTimer app = do
+loop' window renderDdt animationDdt lastAnimationTime inputTimer app = do
   timer        <- gameIO $ tick inputTimer
   windowEvents <- gameIO $ pollWindowEvents window
   close        <- gameIO $ shouldWindowClose window
@@ -91,6 +91,7 @@ loop' window ddt animationDdt lastAnimationTime inputTimer app = do
 
     _ -> do
       -- Fixed time step animation.
+      let ddt = animationDdt
       {- let elapsed = runningTime timer
       let dt = timeDeltaToSec ddt
       let timeBudgetThisFrame = timeBudget + deltaTime timer
@@ -119,11 +120,13 @@ loop' window ddt animationDdt lastAnimationTime inputTimer app = do
     gameIO $ swapBuffers window
 
   -- Limit frame rate if so requested by the application.
+  -- This currently makes the rendering stutter and is not very desirable.
   when ((maxFPS . options $ app) > 0) $ do
     frameEnd <- gameIO now
+    let ddt = renderDdt
     let frameTime = timeDiff (lastTick timer) frameEnd
     when (frameTime < ddt) $ do
       gameIO $ Timer.sleep (ddt - frameTime)
 
   when (continue && not close) $ do
-    loop' window ddt animationDdt lastAnimationTimeNextFrame timer app
+    loop' window renderDdt animationDdt lastAnimationTimeNextFrame timer app