Platform specifics: Windows

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What should I do before the windows created?
Be sure to use the CS_OWNDC flag.
If you are doing plain old WinMain coding, RegisterClassEx() takes the WNDCLASSEX structure.
WNDCLASSEX.style should have the CS_OWNDC
If you are using MFC (SDI or MDI project), override PreCreateWindow and add the CS_OWNDC to cs.
For CDialog based project, PreCreateWindow doesn't get called.
This flag is really needed for Win9x systems.
Since DCs (device contexts) consume resources, the OS does not assign a DC but might share it between multiple windows and GUI elements.
On WinNT and its derivatives, it is said that resources are not a problem and it assigns a unique DC per window.
For good practice, I recommend using CS_OWNDC.


Where is a good place to create the GL context?
When the WM_CREATE message is sent.
This is when the window is created (has a valid HWND and DC).
Normally, the window is visible at this point. Even if you create a invisible window, this is the place to create the GL context.
This is also a good place to make the context current, setup some GL states and setup some things for your program.
For MFC, you override the OnCreate function for your "View" class.

It's flickering! Why?
Windows send a WM_ERASEBKGND message when the background needs to be erased.
Tell Windows that you handled the message by returning a non-zero number (TRUE).
On MFC, override OnEraseBkgnd and just return TRUE.

Where do I render my scene?
If you are making an application like CAD, 3D model viewer or anything that doesn't require constant updating, do it when you receive the WM_PAINT message.

  • Clear the background with glClear
  • Render
  • Swap buffers