Original Post
Greetings, I fired up my Visual Studio this morning and tried to run my OpenGL code, only to find I'm getting an access violation on the call to wglCreateContext(). I've used this initialization code for a very long time, so I have no idea what could have happened to cause this. Any ideas? The full source up to the error is below. Scroll to the bottom to see where it occurs.
bool OGLWindow::CreateOGLWindow(std::string title)
{
unsigned int 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; // Grabs Rectangle Upper Left / Lower Right Values
WindowTitle = title;
WindowRect.left = (long)0; // Set Left Value To 0
WindowRect.right = (long)(Viewports[0])[2]; // Set Right Value To Requested Width
WindowRect.top = (long)0; // Set Top Value To 0
WindowRect.bottom = (long)Viewports[0][3]; // Set Bottom Value To Requested Height
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 = WindowClassName.c_str(); // Set The Class Name
// attempt to register the window class
if (!RegisterClass(&wc))
{
LOG("Failed To Register The Window Class", LOG_ERROR, LOG_HIGH);
// exit and return false
return false;
}
// 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 = Viewports[0][2]; // Selected Screen Width
dmScreenSettings.dmPelsHeight = Viewports[0][3]; // Selected Screen Height
dmScreenSettings.dmBitsPerPel = ResolutionBit; // Selected Bits Per Pixel
dmScreenSettings.dmFields = DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;
// Try to set selected mode and get results.
// NOTE: CDS_FULLSCREEN gets rid of start bar.
if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL)
{
// If the mode fails, offer two options. Quit or run in a window.
if (MessageBoxA(NULL, "The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?", "NeHe GL", MB_YESNO|MB_ICONEXCLAMATION) == IDYES)
{
// Select windowed mode
Fullscreen = false;
}
else
{
// Pop up a message box letting the user know the program is closing
MessageBoxA(NULL, "Program Will Now Close.", "ERROR", MB_OK | MB_ICONSTOP);
// exit and return false
return false;
}
}
}
// Are we still in Fullscreen mode?
if (Fullscreen)
{
// Window Extended Style
dwExStyle = WS_EX_APPWINDOW;
// Windows Style
dwStyle = WS_POPUP;
// Show mouse pointer
ShowCursor(true);
}
else
{
// Window Extended Style
dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
// Windows Style
dwStyle = WS_OVERLAPPEDWINDOW;
// Show mouse pointer
ShowCursor(true);
}
// Adjust Window To True Requested Size
AdjustWindowRectEx(&WindowRect, dwStyle, false, dwExStyle);
// Create our window
if (!(hWnd = CreateWindowEx(dwExStyle, // Extended Style For The Window
WindowClassName.c_str(), // Class Name
WindowTitle.c_str(), // 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
{
// Window not properly created
// Reset the display
DestroyOGLWindow();
LOG("Window Creation Error", LOG_ERROR, LOG_HIGH);
// Return false
return false;
}
// Describe a pixel format
// pfd tells windows how we want things to be
static PIXELFORMATDESCRIPTOR pfd =
{
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
static_cast<BYTE>(ResolutionBit), // 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
16, // 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
};
// Did we get a device context?
if (!(hDC = GetDC(hWnd)))
{
// Reset the display
DestroyOGLWindow();
LOG("Can't Create A GL Device Context", LOG_ERROR, LOG_HIGH);
// Return false
return false;
}
// Did windows find a matching pixel format?
if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd)))
{
// Reset the display
DestroyOGLWindow();
LOG("Can't Find A Suitable PixelFormat", LOG_ERROR, LOG_HIGH);
// Return false
return false;
}
// Are we able to set the pixel format?
if(!SetPixelFormat(hDC, PixelFormat, &pfd))
{
// Reset the display
DestroyOGLWindow();
LOG("Can't Set The PixelFormat", LOG_ERROR, LOG_HIGH);
// Return false
return false;
}
// Are we able to get a rendering context?
if (!(hRC = wglCreateContext(hDC))) // <--- Access violation on this call
{
// Reset the display
DestroyOGLWindow();
LOG("Can't Create A GL Rendering Context", LOG_ERROR, LOG_HIGH);
// Return false
return false;
}