OpenGL overwrites Windows' buttons - c++

Question

I have following code:
void DrawGLScene(unsigned char *drawing_bytes, HDC hdc, int xWidth, int yWidth) {
if ((!xWidth) || (!yWidth)) return;
BOOL returnVal = wglMakeCurrent(hdc, hrc);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, xWidth, yWidth, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, drawing_bytes);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glViewport(0,0,xWidth,yWidth); // Reset The Current Viewport
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
// Calculate The Aspect Ratio Of The Window
gluPerspective(25.0f,1.0f,0.1f,100.0f);
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
glEnable(GL_TEXTURE_2D); // Enable Texture Mapping
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glDisable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
glLoadIdentity(); // Reset The View
glTranslatef(0.0f,0.0f,-5.0f);
glBindTexture(GL_TEXTURE_2D, texture);
glColor4f(1.0, 1.0, 1.0, 1.0);
glBegin(GL_QUADS);
// Front Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.5f);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 0.5f);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.5f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.5f);
glEnd();
glSwapBuffers(hdc);
}
This code overwrites my buttons created earlier via
hInstallButton = CreateWindow(TEXT("button"), "",
WS_VISIBLE | WS_CHILD | BS_AUTOCHECKBOX,
137, 70, 13, 13,
hWnd, (HMENU) 1, GetModuleHandle(NULL), NULL);
The issue is the glSwapBuffers(), which hides the buttons for good.
This is generated by the PIXELFORMATDESCRIPTOR
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
0, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
24, // 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
};
How can I force a single buffer, or something to write the buttons to both buffers? I am at a good loss here, and don't know how to do it properly (except maybe recreate the buttons with each WM_PAINT call)?
Edit:
Tried with subwindow (see code), but it creates a second window, instead of embedding into the first window.
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HWND hWnd;
hInst = hInstance; // Instanzenhandle in der globalen Variablen speichern
DWORD dwExStyle; // Window Extended Style
DWORD dwStyle; // Window Style
hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
if (!hWnd) {
return FALSE;
}
dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE | CS_OWNDC; // Window Extended Style
dwStyle=WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN; // Windows Style
WNDCLASS wndClass;
wndClass.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
wndClass.lpfnWndProc = WndProc;
wndClass.cbClsExtra = 0;
wndClass.cbWndExtra = 0;
wndClass.hInstance = hInstance;
wndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndClass.hbrBackground = CreateSolidBrush(BLACK_BRUSH);
wndClass.lpszMenuName = NULL;
wndClass.lpszClassName = "Test Window";
RegisterClass(&wndClass);
hWndOpenGL = CreateWindowEx( dwExStyle, // Extended Style For The Window
"Test Window", // Class Name
"Testy test", // Window Title
dwStyle, // Required Window Style
0, 0, // Window Position
800,
600,
hWnd, // Parent Window
NULL, // No Menu
hInstance, // Instance
NULL);
//CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
//CW_USEDEFAULT, 0, CW_USEDEFAULT-500, 0, hWnd, NULL, hInstance, NULL);
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
0, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
24, // 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
};
hdcOpenGL=GetDC(hWndOpenGL);
GLuint PixelFormat; // Holds The Results After Searching For A Match
PixelFormat=ChoosePixelFormat(hdcOpenGL,&pfd);
SetPixelFormat(hdcOpenGL,PixelFormat,&pfd);
hrc=wglCreateContext(hdcOpenGL);
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
ShowWindow(hWndOpenGL, nCmdShow);
UpdateWindow(hWndOpenGL);
return TRUE;
}

Answer 1

I'm guessing that you created the buttons as childs of the OpenGL window. If you did this, well, then you actually did something, that's explicitly mentioned in the WGL and Win32 API documentation to break things .
The fix is simple: The OpenGL window should be a sibling to the buttons and have its very own DC: Create a own subwindow for OpenGL operations with the CS_OWNDC window class flag set and the WS_CLIPSIBLINGS | WS_CLIPCHILDREN window styles being set. Both the OpenGL subwindow and the buttons are created with the desired container window as parent.
That way the buttons will not get clobbered by OpenGL operations, even with a double buffered pixelformat.