Win32.. Game Loop

Win32.. Game Loop

decsonic

Member #4,150

December 2003

Came Across some problems when handling the WinMain my self,

1// the message "loop" 
2GameInit();  
3 
4  while( 1 )
5  { 
6    if( PeekMessage( &msg, NULL, 0, 0, PM_NOREMOVE ) )  
7    {    
8    if( !GetMessage( &msg, NULL, 0, 0 ) )    
9      {      
10        return msg.wParam;    
11      }   
12      TranslateMessage(&msg);    
13      DispatchMessage(&msg);  
14    }  else
15      GameUpdate(); // Run the Game
16  }
17 
18  GameQuit(); // Finish it.
19}
20 
21//Game Update
22int GameUpdate()
23{
24 
25blit(image, buffer, 0,0,0,0, 400,400);
26SendMessage(hwnd,WM_PAINT,0,0);
27}
28 
29//Case WM PAINT
30   HDC             hdc;
31   PAINTSTRUCT     ps;
32 
33switch(message)
34{
35        case WM_PAINT:
36            hdc = BeginPaint( hwnd, &ps  );
37            blit_to_hdc(buffer, hdc, 0, 0, 0, 0, 800, 600);
38            EndPaint( hwnd, &ps );
39        return 0;
40        break;
41//... a few others
42}

buffer is a double buffer.
It draws when i focus away from the window, checked if it actualy goes inside the game update function and WM_PAINT.. and hum yea it does, had a pop up window to check, almost crashed my comp to many off them,
Any one know how to go about this? as im shure my idea isnt the best,
(without multithreading).
cheers

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gillius

Member #119

April 2000

I don't understand what your problem is? Are you trying to get WM_PAINTs or???

Gillius
Gillius's Programming -- https://gillius.org/

decsonic

Member #4,150

December 2003

Well i dont get why hdc doesnt get blitted, done a few tests, it goes inside WM_PAINT alot and my "Game Update" function (off course since WM paint is forced there.)
Basicly im asking how others do their Game Loop with win32

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gillius

Member #119

April 2000

what do you mean HDC... Are you trying to use Allegro and then blit to the HDC? Yes you are. Are you sure that the buffer contains the proper image that you are expecting?

EDIT: do you have to get a HDC every time you paint? I don't know Win32 very well but it seems you store the HDC once and don't get it in WM_PAINT. Honestly I can't remember if you can do that.

Gillius
Gillius's Programming -- https://gillius.org/

Thomas Fjellstrom

Member #476

June 2000

I found the BeginPaint thing says its supposed to give a valid HDC.. but it doesnt. so I grabbed mine from the ps struct (IIRC, been a while since I looked at my win32 code...)

--
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"If you can't think of a better solution, don't try to make a better solution." -- weapon_S
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decsonic

Member #4,150

December 2003

ahh 1 thing i forgot,
it draws when its in the background, ie. if i open Winamp or a browser window ect.
Not to experienced with Win32 API, lived happly in the

int main()
{
}

"world"
edit:
a bit late to be posting questions, might be a bit unclear.. sorry hehe.
In short, Is there reason that code posted above shouldnt Blit the buffer?

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Kitty Cat

Member #2,815

October 2002

I think the only time it's not supposed to draw is when it's minimized. If you're app is in the background, it can still be visible, even if only partially, or if the window on top is translucent. It sounds like, though, that you want your game to pause execution when you go into the background. I don't know how to do that.

EDIT:
Oh, I got that backwards.. hmm. I dunno.

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decsonic

Member #4,150

December 2003

the problem is that it doesnt draw when it has focus

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A J

Member #3,025

December 2002

are you waiting on a WM_PAINT msg before you draw to the screen ?

i think you will only receive a WM_PAINT when the window changes state or it gets un-obscured by another window.

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23yrold3yrold

Member #1,134

March 2001

Program might be waiting for a new message when it has the focus. Maybe set up a WM_TIMER?

And you can call InvalidateRect() instead of sending WM_PAINT messages. That might help too ... actually, yes. That might be your problem. Sending a WM_PAINT message might be totally wasted if there's no "dirty" areas that need updating.

--
Software Development == Church Development
Step 1. Build it.
Step 2. Pray.

Rick

Member #3,572

June 2003

Why are you doing it this way? You shouldn't be calling the WM_PAINT message to update the screen. Update the screen in GameUpdate.

========================================================
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Specter Phoenix

Member #1,425

July 2001

This is the just of my code nowadays from learning WinAPI/DirectX:

1int WINAPI WinMain(HINSTANCE hinstance, HINSTANCE hprevinstance, LPSTR lpcmdline, int ncmdshow)
2{
3WNDCLASSEX winclass;
4HWND hwnd;
5MSG  msg;
6HDC  hdc;
7 
8winclass.cbSize   = sizeof(WNDCLASSEX);
9winclass.style    = CS_DBCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
10winclass.lpfnWndProc =WindowProc;
11winclass.cbClsExtra =0;
12winclass.cbWndExtra =0;
13winclass.hInstance =hinstance;
14winclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
15winclass.hCursor = LoadCursor(NULL, IDC_CROSS);
16winclass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
17winclass.lpszMenuName =NULL;
18winclass.lpszClassName ="WINCLASS1";
19winclass.hIconSm =LoadIcon(NULL, IDI_APPLICATION);
20 
21if(!RegisterClassEx(&winclass))
22return(0);
23 
24if(!(hwnd = CreateWindowEx(NULL, "WINCLASS1", "Title", WS_POPUP | WS_VISIBLE, 0,0, 400, 300, NULL, NULL, hinstance, NULL)))
25return(0);
26 
27Game_Init();
28 
29while(TRUE)
30{
31if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
32{
33if(msg.message == WM_QUIT)
34break;
35 
36TranslateMessage(&msg);
37 
38DispatchMessage(&msg);
39}//end if
40Game_Main();
41}// end while
42Game_Shutdown();
43 
44return(msg.wParam);
45}// end WinMain

Of course for the WNDCLASSEX I use the shorter form to save typing:

WNDCLASSEX winclass = {
 winclass.cbSize = sizeof(WNDCLASSEX), CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW,
 WindowProc, 
0, 
0, 
hinstance, 
LoadIcon(NULL, IDI_APPLICATION), 
LoadCursor(NULL, IDC_CROSS), 
(HBRUSH)GetStockObject(BLACK_BRUSH), NULL, 
"WINCLASS1", 
LoadIcon(NULL, IDI_APPLICATION)
};

I use WS_POPUP for use with DX:).
[edit]Almost forgot to answer the problem. Unless the screen is constantly updating there is now point in use WM_PAINT cause it will just put the data in the buffer and display it:(.

decsonic

Member #4,150

December 2003

void Update( HWND hWnd )
{
HDC DC = BeginPaint(hWnd,&ps);
 blit_to_hdc( buffer, DC,0,0,0,0,800,600);
EndPaint( hWnd, &ps );
}

atm that just crashes::)

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23yrold3yrold

Member #1,134

March 2001

Do you create 'buffer' anywhere?

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Software Development == Church Development
Step 1. Build it.
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decsonic

Member #4,150

December 2003

yup its a double buffer, 800,600.
changing to Dx now i think anyways, been avoiding this for to long:P

Programmer's paranoia: Don't trust anybody's code, not even your own.

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