I'm wondering if it's possible to toggle back and forth between fullscreen mode and windowed mode in an OpenGL window(I'm writing for Windows using C++ and win32), without destroying the OpenGL context, and thus having to reload assets(Textures, VBOs, etc) in the process?
This is undesirable because it introduces a delay in switching between fullscreen and windowed mode, potentially a long one, as well as making it easier to screw things up by forgetting to reinitialize something.
As a followup to that, are there certain visual effects that are broken by managing to do this?
I've done a fair bit of searching and reading for the past few days, and despite a lot of flaming of SDL and other frameworks for having the same problem(I'm not using them anyway, but...), the best I've managed to find is a possible lead on opening a 1x1 window in the background to retain the context while a secondary window is destroyed or created at whim. And that's seeming unreliable from the comments I found regarding it, and seems very kludgey regardless.
Is there a proper way to do this, or is the proper way the often-given-as-an-example method of destroying your window, and recreating it, including destroying your OpenGL context and recreating it?
Basically it's just resizing the window and specifying flags that the border is invisible.
SetWindowLongPtr(hWnd, GWL_STYLE,
WS_SYSMENU | WS_POPUP | WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_VISIBLE);
MoveWindow(hWnd, 0, 0, width, height, TRUE);
to set it back:
RECT rect;
rect.left = 0;
rect.top = 0;
rect.right = width;
rect.bottom = height;
SetWindowLongPtr(hWnd, GWL_STYLE, WS_OVERLAPPEDWINDOW | WS_VISIBLE);
AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, FALSE);
MoveWindow(hWnd, 0, 0, rect.right-rect.left, rect.bottom-rect.top, TRUE);
or for a not-resizable window:
SetWindowLongPtr(hWnd, GWL_STYLE, WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE);
AdjustWindowRect(&rect, WS_CAPTION | WS_POPUPWINDOW, FALSE);
MoveWindow(hWnd, 0, 0, rect.right-rect.left, rect.bottom-rect.top, TRUE);
and then just resize your OpenGL viewport settings.
If you want to set the display mode too, use this:
// change display mode if destination mode is fullscreen
if (fullscreen) {
DEVMODE dm;
dm.dmSize = sizeof(DEVMODE);
dm.dmPelsWidth = width;
dm.dmPelsHeight = height;
dm.dmBitsPerPel = bitsPerPixel;
dm.dmFields = DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL;
success = ChangeDisplaySettings(&dm, 0) == DISP_CHANGE_SUCCESSFUL;
}
// reset display mode if destination mode is windowed
if (!fullscreen)
success = ChangeDisplaySettings(0, 0) == DISP_CHANGE_SUCCESSFUL;