View Full Version : Weird framerate problem

10-11-2003, 07:01 AM
I'm programming a Pacman game (how original ? hehe) mainly to learn how directdraw works.

Everything is perfect except for one small problem.

The framerate drops for about 2 seconds on the 3rd second of play and then goes back to normal for the rest of the game. If I start a new game the slowdown does not happen.

1.Game starts
2. Frame rate is 33 for the first 2-3 seconds
3. Drops to 22 for about 2 seconds
4. Goes up to 33 and never change after that.
5. If the game is over I restart a new game..and no slowdown
6. If I close the exe and run it again I'll get the slowdown for the first game

It's really weird.

Any idea ?

10-11-2003, 07:19 AM
hmmm I have set dowaitvblank and the framerate is pretty much stable now.

Anyone can explain it to me ? I find it very strange I get a slowdown when dowaitvblank is true only at a particular time and when a game restarts (i.e the game displays the same number of sprites) the slowdown does not happen.

10-11-2003, 07:25 AM
oops nevermind I still have the problem.
It's driving me crazy.

I reduced the timer interval and disabled the collisions detection and I still have the problem.

100 fps for the first seconds...then a big drop for an unknown reason and back to 100 for the rest of the game.

10-11-2003, 08:03 AM
What's your game doing the first time you start it?

It's possibly just a glitch in the DX timer of DelphiX -- though that isn't likely. Have you tested whether this occurs on other machines (if not, post a download link here for us to check it).

Create an empty DelphiX project that does nothing but (e.g.) display the frame rate. See if the fall-off and recovery happens in that. If it doesn't then it's something specific to your code.

10-11-2003, 08:52 AM
Additional info

If I add a sleep() long enough (something like 9000) after the sprites craetion and the main draw routine I don't get the slowdown.


procedure TForm1.DXTimerTimer(Sender: TObject; LagCount: Integer);
if (not DXDraw.CanDraw) then exit;
if titlescreen then scenetitle else
if not(pause) then maindraw;

and in the scenetitle procedure when the space key is pressed:
CreateSprites; //Procedure that creates the sprites

I really don't get it. It must be a stupid thing.

10-11-2003, 10:37 AM
Another weird thing. If I run it from Delphi I have no slowdown.
If I run it from the Explorer I have the slowdown.

hmmm It seems it's not my code.

I tried a sample that comes with DelphiX (the shooter) and modified the title screen to display the framerate. If I run it from Delphi it's stable and if I run it from the explorer there is also a slowdown.

No other application is running
I have XP