Does Displaying in FullScreen diable 'rendering' of other windows in GLUT - c++

Currently developing an APP using C++.
I am displaying multiple sub-windows in a single main window.
When one of the subwindows is put in Full Screen Mode , does the rendering of the other windows stop?

does the rendering of the other windows stop?
That depends on the implementation. If the program is implemented correctly, then the rendering should stop only if the window is fully covered.
Some people like to update the window in a timer callback (which is a bad practice), and then it would continue to render even when covered.
glutDisplayFunc is called only when there is a need to refresh the window.

Related

WIndows Flickering when changing focus in OpenGL

I'm working on a project that requires me to switch between two windows, one using OpenCV and one using OpenGL, both fullscreen.
A GLFW key event opens the OpenCV window fine, but closing the OpenCV window, and attempting to return focus to the OpenGL window results in the window flickering and repeatedly attempting to give focus. This is my code to return focus to the OpenGL window, inside a while loop.
Edit: Ive found out that it only happens when the OpenGL window is fullscreen, which is a requirement of this program. Writing to console shows that the code is being called multiple times
if(!glfwGetWindowAttrib(window, GLFW_FOCUSED))
{
glfwFocusWindow(window);
while(!glfwGetWindowAttrib(window, GLFW_FOCUSED))
{
}
}
I managed to fix my problem by setting the GLFW flag GLFW_AUTO_ICONIFY to false on my openGL window.
The way you posted is not the proper way to set focus.
Use glfwSetWindowCloseCallback to set a close callback.
In that callback is where you set focus to another window.

How are opengl menus that go outside of the window implemented?

I was looking at how sometimes when you right click, the menu goes outside of the window.
Is this implemented with a separate window? If so, how can I get this functionality. I am trying to use GLFW, but I understand if it isn't possible.
Currently I am on windows, but I like keeping my options open, which is why GLFW would be preferable.
I noticed that GLUT has such a feature. If you are confused to what I am looking at then look at that.
Thanks for any help!!
Overlapping menus (in MS Windows) have to be implemented as a new top-level window, you would have a new OpenGL rendering context and draw the menu in that space - yes, it's a fair bit of work all for the edge-case of a menu overspilling the parent window,
However this isn't often a problem in OpenGL programming because if you're working on a full-screen game then the menu will always be displayed within the main window, and even if it isn't a full-screen a game your users really won't notice them as games tend to use different UI concepts like radial-menus which wouldn't overspill the parent window.
Or if you're working on a non-game title, chances are it isn't full-screen and is going to be an OpenGL rendering area within a larger application that is rendered using a native UI toolkit (e.g. 3ds Max, AutoCAD, etc), in which case no problem: just use native menus.
You can, of course, use native menus in an OpenGL application anyway, provided you do the necessary plumbing for native window messages.

Draw OpenGL on the windows desktop without a window

I've seen things like this and I was wondering if this was possible, say I run my application
and it will show the render on whatever is below it.
So basically, rendering on the screen without a window.
Possible or a lie?
Note: Want to do this on windows and in c++.
It is possible to use your application to draw on other application's windows. Once you have found the window you want, you have it's HWND, you can then use it just like it was your own window for the purposes of drawing. But since that window doesn't know you have done this, it will probably mess up whatever you have drawn on it when it tries to redraw itself.
There are some very complicated ways of getting around this, some of them involve using windows "hooks" to intercept drawing messages to that window so you know when it has redrawn so that you can do your redrawing as well.
Another option is to use clipping regions on a window. This can allow you to give your window an unusual shape, and have everything behind it still look correct.
There are also ways to take over drawing of the desktop background window, and you can actually run an application that draws animations and stuff on the desktop background (while the desktop is still usable). At least, this was possible up through XP, not sure if it has changed in Vista/Win7.
Unfortunately, all of these options are too very complex to go in depth without more information on what you are trying to do.
You can use GetDesktopWindow(), to get the HWND of the desktop. But as a previous answer says (SoapBox), be careful, you may mess up the desktop because the OS expects that it owns it.
I wrote an open source project a few years ago to achieve this on the desktop background. It's called Uberdash. If you follow the window hierarchy, the desktop is just a window in a sort of "background" container. Then there is a main container and a front container. The front container is how windows become full screen or "always on top." You may be able to use Aero composition to render a window with alpha in the front container, but you will need to pass events on to the lower windows. It won't be pretty.
Also, there's a technology in some video cards called overlays/underlays. You used to be able to render directly to an overlay. Your GPU would apply it directly, with no interference to main memory. So even if you took a screen capture, your overlay/underlay would not show up in the screen cap. Unfortunately MS banned that technology in Vista...

Handling minimisation in Fullscreen Win32 OpenGL

I'm trying to create a fullscreen application using Win32 and OpenGL. I change the resolution using EnumDisplaySettings and ChangeDisplaySettings and the OpenGL functions work fine. On its WndProc I handle WM_ACTIVATEAPP and detect when the user switched focus to another window, then I minimize the application's window. When the window is maximized again, the window doesn't display properly at all. What could I include to make the application work even after minimizing?
From the question I cannot still say what you are missing and what you already have. Refer to the http://nehe.gamedev.net/. There is a section Opengl base code to setup a window in full screen and switch back to window mode. See if you can get something from there.

Windows not drawing above OpenGL windows

I have an application with an OpenGL window as a child window of the main window.
When I display a dialog box above the OpenGL window, it doesn't get drawn. It's like it's not getting WM_PAINT messages. If I can guess the title bar position of the dialog box, I can drag it and it's still responsive.
I realise this might be a vague question, but I was wondering if anyone else has seen this sort of behaviour before and knew of a solution?
I wondered if the Pixel Format Descriptor would make a difference - I had PFD_DRAW_TO_WINDOW, but changing to PDF_DRAW_TO_BITMAP didn't make any difference. I'm not sure what else I should be looking at?
Bugger. Should have given all the details. I was running Windows in a virtual machine on Mac OS X using Parallels. I upgrade from Parallels 3 to 4 and now everything is working fine. I suspect a Parallels video driver issue.
Thanks to all those who answered with suggestions.
Is your opengl window constantly rendering. It is possible that the 3D hardware is simply rendering into an overlay that is overdrawing your dialog box. If you position the dialog box so it overlaps your main window, can you see some of it?
Try to pause rendering into the main display to see if it effects the results.
You will also need to make sure that your window style ensures the results are clipped...
cs.style |= WS_CLIPSIBLINGS | WS_CLIPCHILDREN ;
You should check though all the items mentioned in this MSDN article, as it covers a lot of the basics for getting opengl rendering in a window correctly.
http://msdn.microsoft.com/en-us/library/ms970745.aspx
You may need to switch overlay off. It can be done via forcing back buffer presenting method to copy instead of swap.
Use wglChoosePixelFormatARB and one of parameters should be
WGL_SWAP_METHOD_ARB with value WGL_SWAP_COPY_ARB
This may seems stupid but are you sure your OpenGL window is not flagged "topmost" ?
Does the dialog box disappear also behind borders of your window or just behind the OpenGL rendering rectangle ?