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View Full Version : wglMakeCurrent causes program to hang



05-20-2003, 08:16 AM
I am trying to create an opengl window on a win98 system and when wglMakeCurrent() gets called the application hangs. It seems that wglMakeCurrent() never returns from the call.

The application doesn't use MFC and is single-threaded. Any ideas?

code:



BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
GLuint PixelFormat; // Holds The Results After Searching For A Match
WNDCLASS wc; // Windows Class Structure

DWORD dwExStyle; // Window Extended Style
DWORD dwStyle; // Window Style

RECT WindowRect;
WindowRect.left=(long)0;
WindowRect.right=(long)width;
WindowRect.top=(long)0;
WindowRect.bottom=(long)height;

static PIXELFORMATDESCRIPTOR pfd= // pfd Tells Windows How We Want Things To Be
{
sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
1, // Version Number
PFD_DRAW_TO_WINDOW | // Format Must Support Window
PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
PFD_DOUBLEBUFFER, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
bits, // Select Our Color Depth
0, 0, 0, 0, 0, 0, // Color Bits Ignored
0, // No Alpha Buffer
0, // Shift Bit Ignored
0, // No Accumulation Buffer
0, 0, 0, 0, // Accumulation Bits Ignored
24, // 16Bit Z-Buffer (Depth Buffer)
0, // No Stencil Buffer
0, // No Auxiliary Buffer
PFD_MAIN_PLANE, // Main Drawing Layer
0, // Reserved
0, 0, 0 // Layer Masks Ignored
};


// Set The Global Fullscreen Flag
fullscreen=fullscreenflag;

hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window
wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Move, And Own DC For Window
wc.lpfnWndProc = (WNDPROC) WndProc; // WndProc Handles Messages
wc.cbClsExtra = 0; // No Extra Window Data
wc.cbWndExtra = 0; // No Extra Window Data
wc.hInstance = hInstance; // Set The Instance
wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon
wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer
wc.hbrBackground = NULL; // No Background Required For GL
wc.lpszMenuName = NULL; // We Don't Want A Menu
wc.lpszClassName = "OpenGL"; // Set The Class Name


// Attempt To Register The Window Class
if (!RegisterClass(&wc))
{
MessageBox(NULL,"Failed To Register The Window Class.",
"ERROR",MB_OK|MB_ICONEXCLAMATION);

return FALSE;
}

wprintf("registered...\n");

// Attempt Fullscreen Mode?
if (fullscreen)
{
DEVMODE dmScreenSettings; // Device Mode
memset(&dmScreenSettings,0,sizeof(dmScreenSettings )); // Makes Sure Memory's Cleared
dmScreenSettings.dmSize=sizeof(dmScreenSettings); // Size Of The Devmode Structure
dmScreenSettings.dmPelsWidth = width; // Selected Screen Width
dmScreenSettings.dmPelsHeight = height; // Selected Screen Height
dmScreenSettings.dmBitsPerPel = bits; // Selected Bits Per Pixel
dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWID TH|DM_PELSHEIGHT;

// Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLS CREEN)!=DISP_CHANGE_SUCCESSFUL)
{

// If The Mode Fails, Offer Two Options. Quit Or Run In A Window.
if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
{
fullscreen=FALSE; // Select Windowed Mode (Fullscreen=FALSE)
}
else
{
// Pop Up A Message Box Letting User Know The Program Is Closing.
MessageBox(NULL,"Program Will Now Close.",
"ERROR",MB_OK|MB_ICONSTOP);

return FALSE;
}
}
}


// Are We Still In Fullscreen Mode?
if (fullscreen)
{
dwExStyle=WS_EX_APPWINDOW; // Window Extended Style
dwStyle=WS_POPUP; // Windows Style
ShowCursor(FALSE); // Hide Mouse Pointer
}
else
{
dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window Extended Style
dwStyle=WS_OVERLAPPEDWINDOW; // Windows Style
}


wprintf("sizing...\n");

// Adjust Window To True Requested Size
AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);

hWnd=CreateWindowEx( dwExStyle, // Extended Style For The Window
"OpenGL", // Class Name
title, // Window Title
WS_CLIPSIBLINGS | // Required Window Style
WS_CLIPCHILDREN | // Required Window Style
dwStyle, // Selected Window Style
0, 0, // Window Position
WindowRect.right-WindowRect.left, // Calculate Adjusted Window Width
WindowRect.bottom-WindowRect.top, // Calculate Adjusted Window Height
NULL, // No Parent Window
NULL, // No Menu
hInstance, // Instance
NULL); // Don't Pass Anything To WM_CREATE

if (!hWnd)
{
KillGLWindow();

MessageBox(NULL,"Window Creation Error.","ERROR",
MB_OK|MB_ICONEXCLAMATION);

return FALSE;
}


// Did We Get A Device Context?
if (!(hDC=GetDC(hWnd)))
{
KillGLWindow();

MessageBox(NULL,"Can't Create A GL Device Context.",
"ERROR",MB_OK|MB_ICONEXCLAMATION);

return FALSE;
}


// Did Windows Find A Matching Pixel Format?
if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))
{
KillGLWindow();

MessageBox(NULL,"Can't Find A Suitable PixelFormat.",
"ERROR",MB_OK|MB_ICONEXCLAMATION);

return FALSE;
}

// Are We Able To Set The Pixel Format?
if(!SetPixelFormat(hDC,PixelFormat,&pfd))
{
wprintf("SetPixelFormat failed.\n");

KillGLWindow();

return FALSE;
}

// Are We Able To Get A Rendering Context?
if (!(hRC=wglCreateContext(hDC)))
{
wprintf("wglCreateContext failed.\n");

KillGLWindow();

return FALSE;
}

// Try To Activate The Rendering Context
if(!wglMakeCurrent(hDC,hRC))
{
wprintf("wglMakeCurrent failed.\n");

KillGLWindow();

return FALSE;
}


wprintf("context registered...\n");

ShowWindow(hWnd,SW_SHOW); // Show The Window
SetForegroundWindow(hWnd); // Slightly Higher Priority
SetFocus(hWnd); // Sets Keyboard Focus To The Window

ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen

return TRUE;
}