Crashing on prog quit

Hey guys! I'm currently learning DirectX (DirectDraw to be specific), in order to recode my game (you can check out the GDI version in my sig). But this simple prog keeps giving me an illegal operation whenever I close it! No idea what's wrong, except that my init/shutdown code was working fine before... Well, this is the relevant code:

PHP Code:

#include <ddraw.h>
#include "main.h" //function prototypes

#define WINDOW_CAPTION "DirectX Pixelz"
#define WINDOW_WIDTH 640
#define WINDOW_HEIGHT 480
#define WINDOW_POS_X 0
#define WINDOW_POS_Y 0

#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480

HWND hWnd;
bool done;
LPDIRECTDRAW ddraw;
LPDIRECTDRAWSURFACE surfacePrimary, surfaceSecondary;
unsigned char* videoBuffer;
DDSURFACEDESC desc = {0};
DDSCAPS ddscaps;
int x, y;

void registerWindowClass()
{
    WNDCLASSEX wc = {0};

    wc.cbSize = sizeof(wc);
    wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hInstance = GetModuleHandle(NULL);
    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = "WndClass";
    
    RegisterClassEx(&wc);
}

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR cmd, int showCmd)
{
    srand((unsigned int)GetTickCount());
    registerWindowClass();

    hWnd = CreateWindowEx(0, "WndClass", WINDOW_CAPTION, WS_POPUP, WINDOW_POS_X, WINDOW_POS_Y, WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, hInst, NULL);
    ShowWindow(hWnd, SW_SHOW);

    if(!gameInit())
        return 1;

    MSG msg;
    while(!done)
    {
        while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        gameMain();
    }

    gameShutdown();

    return 0;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_CLOSE:
        done = true;
        DestroyWindow(hWnd);
        return 0;

    case WM_KEYDOWN:
        switch((int)wParam)
        {
        case 'Q':
            done = true;
            DestroyWindow(hWnd);
            break;
        }
        return 0;
    }

    return DefWindowProc(hWnd, msg, wParam, lParam);
}

bool gameInit()
{
    desc.dwSize = sizeof(desc);
    desc.dwFlags = DDSD_CAPS | DDSD_BACKBUFFERCOUNT;
    desc.dwBackBufferCount = 1;
    desc.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE |
        DDSCAPS_FLIP | DDSCAPS_COMPLEX;

    if(DirectDrawCreate(NULL, &ddraw, NULL) != DD_OK)
        return false;

    if(ddraw->SetCooperativeLevel(hWnd, DDSCL_EXCLUSIVE | DDSCL_FULLSCREEN | DDSCL_ALLOWMODEX | DDSCL_ALLOWREBOOT) != DD_OK)
        return false;

    if(ddraw->SetDisplayMode(SCREEN_WIDTH, SCREEN_HEIGHT, 8) != DD_OK)
        return false;

    if(ddraw->CreateSurface(&desc, &surfacePrimary, NULL) != DD_OK)
        return false;

    ddscaps.dwCaps = DDSCAPS_BACKBUFFER;

    if(surfacePrimary->GetAttachedSurface(&ddscaps, &surfaceSecondary) != DD_OK)
        return false;

    return true;
}

void gameMain()
{
    memset(&desc, 0, sizeof(desc));
    desc.dwSize = sizeof(desc);
    surfaceSecondary->Lock(NULL, &desc, DDLOCK_SURFACEMEMORYPTR | DDLOCK_WAIT, NULL);
    videoBuffer = (unsigned char*)desc.lpSurface;
    
    if(desc.lPitch == SCREEN_WIDTH)
        memset(videoBuffer,0,SCREEN_WIDTH*SCREEN_HEIGHT);
    else
    {
        unsigned char* asdf = videoBuffer;

        for(int i = 0; i < SCREEN_HEIGHT; ++i)
        {
            memset(asdf, 0, SCREEN_WIDTH);
            asdf += desc.lPitch;
        }
    }
    

    for(int i = 0; i < 1000; ++i)
    {
        x = rand() % SCREEN_WIDTH;
        y = rand() % SCREEN_HEIGHT;
        
        videoBuffer[x + (y * (desc.lPitch))] = rand() % 256;
    }
    
    surfaceSecondary->Unlock(videoBuffer);
    while(surfacePrimary->Flip(NULL, DDFLIP_WAIT) != DD_OK && (!done));
}

void gameShutdown()
{
    if(surfaceSecondary != NULL)
        surfaceSecondary->Release();
    if(surfacePrimary != NULL)
        surfacePrimary->Release();
    if(ddraw != NULL)
        ddraw->Release();
} 


Anyone have any quick pointers?

It's late and I'm pretty tired but off hand I noticed that you aren't setting your pointers to NULL/0 after you release them (surface/DD object).

Tomorrow morning (after I've had some sleep and coffee) I'll take a closer look at it.

***edit*** I just noticed you're releasing your backbuffer individually. Your backbuffer (when it's an attached surface to a complex primary surface) is cleaned up by releasing it's attached-to primary surface. Check the DX docs, under the Ddraw section, it explains it.

What's most likely happening is that you're releasing it then it's not their when it's "parent" surface is trying to release it in the next line. You can take the lines to release the backbuffer out entirely.

The only time you'd want to release your backbuffer individually is when you're using Windowed Ddraw (which is SLOW) and your backbuffer isn't an attached surface but instead a regular off-screen surface.

Ok Well, I guess it doesn't surprise me even though I took the releasing stuff right out of a book... the book I'm using has a typo/bug every couple of pages I guess I'll try taking out the backbuffer-releasing lines though

Hmm, not working I've alternatingly taken out the secondary surface's release, the primary's, and the main directdraw's (just to see what was the problem), but it crashed no matter what. Hope you've had some sleep and coffee, jdinger

**EDIT**
I ran it through the debugger again, and it miraculously didn't freeze! It said there was an unhandled exception, then zoomed into the file in which memset() is implemented (in assembler ). So I figure it's gotta be somewhere in gameMain(), since that's where all the memset()'s are...

**EDIT Final**
NVM, I think I figured it out When the window received a WM_QUIT message, it would set 'done' to true, and then call DestroyWindow(). I'm thinking that this is bad, since gameMain() gets called after, and then tries to clear the screen by memsetting videobuffer, which (by my reasoning) might be null. So I just added an if statement, and if done was true then it would skip over everything

This actual problem was discussed on the Windows board by me and ken a week or so ago. We came to the conclusion that by using PeekMessage you are unable to call DestroyWindow from the WM_CLOSE message but should instead be called from the DestroyMethod after the message loop or from your class's destructor.

"DestroyMethod"? You mean, just a method to destroy everything? (i.e. gameShutdown()?) And why can't it be called from the WM_CLOSE message?

Hunter, for Windows clean-up, here is what I use (and I have no/nor have I ever had any problems with it):

Code:

//this is all that is at the bottom of my winmain() after the basic 
//window's class set-up/registration/creation

if(!InitGame()) return(0);
MSG msg;
for(;;)
{
    if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))
   {
     if(msg.message==WM_QUIT) break;
     TranslateMessage(&msg);
     DispatchMessage(&msg);
   }
   MainLoop();
}
CleanUp();
return(msg.wParam);

And in my message handler (Window proc):

Code:

case WM_DESTROY:
{
  PostQuitMessage(0);
  return(0);
}break;

And that's it.

Ok, sounds simple enough... But doesn't Windows automatically post a WM_QUIT message if the WM_DESTROY isn't handled?...

Oh yeah, and I was just wondering why you used "for(;". Is it faster than "while(true)" or neater or something?

Originally posted by Hunter2
Oh yeah, and I was just wondering why you used "for(;". Is it faster than "while(true)" or neater or something?

hehe, I honestly don't have a great answer for that. It's just the way I was originally taught and it's never failed me.

Ok then

I dont know why you cant call it from WM_CLOSE all I know is that it wont work if your using a message pump using PeekMessage

Hmm, I was looking at my code and I noticed that at the beginning of gameMain() I empty 'desc' and re-enter its size. I tried commenting out those lines, and it seemed to work fine... is there any reason why I should keep them there?

P.s. A book I'm using had those lines, so I used them too... but the book is error/redundancy-infested, so I don't know whether or not to do the memset.