Re: [Dev-C++] WinAPI help...

[Emiliano <sky...@fa...>]

First of all, thank you again for your precious hints.

----- Original Message ----- 
From: "Per Westermark" <pw...@ia...>
To: "Emiliano" <sky...@fa...>
Cc: <dev...@li...>
Sent: Friday, February 27, 2004 4:30 PM
Subject: Re: [Dev-C++] WinAPI help...


> Unless this is a movie viewer or similar, where the drawed material
> requires a fixed frame rate, you shouldn't create the code for a fixed
> frame rate, since you can't know the speed of the machine, and amount of
> other programs currently needing processing time.

No, I need just to update the 3d world at regular time intervals. Of course,
the updating function is supposed to be simple and fast.

> You might use GetTickCount() to getch which millisecond you started draw.
> When the thread has drawn everything, it calls  GetTickCount() again. The
> difference between these two represents number of used ms. You may then
> Sleep(xx-consumed) ms. Call GetTickCount() and check how lock you slept
> since all you know is that the program slept >= xx-consumed.
> The disadvantage with the above solution is that if the drawing takes >=
> allowed time, the machine will spend 100% of available capacity drawing.

> You might instead define that it is the sleep time between end of one
> frame and start of drawing of next frame that should fixed.

Yes, but if I'm not wrong, in this way I could have a very fast world when
the scene is simple, and a very slow one when the scene is full of stuff.

> You might also use the DirectX methods for drawing your information - they
> have functions for synchronizing frame rates. Alas, I don't know how to
> program with DirectX in the Dev-C++ environment. I have only tried this
> with M$ VC++.

I think DX won't work with dev-cpp, uh? :))

> About your "strage" framerate: Windows tries to run threads for full
> time slices before swapping.

Thread with the timer func: "GetMessage() -> Dispatch()" (the doc says that
with a TimerFunc, no message is posted to the thread queue... but I still
need GetMessage() for it to work!!!)

Thread handling the window: "GetMessage() -> Dispatch()"
Thread performing the drawing: "WaitForSingleObject() -> draw()"

Two more questions:

1) I have the timer running as HIGHEST priority, main task is normal and
drawing task IDLE. Has this something to do with time slices given to each
thread? I thougt that with Wait/GetMessage each thread went active only when
it had a message waiting...

2) Sometime I press esc, a PostQuitMessage(0); is issued (as the debug
output says)... but I must be losing it, since the program goes on!! Or the
win thread goes into starvation?? I can't say.

thanks again,
Emiliano