On 11/14/19 18:23, Henri Verbeet wrote:
But the application is trying to present a swapchain into the window it specified, the resource is onscreen (if we imagine that it is going to draw something in some other case with a visible window, as here the window is 1x1 and invisible). Does it make sense if we create another invisible window instead and present something to the drawable obtained from it?
Somewhat, in the sense that it gives us the option of using e.g. (gdi32) BitBlt() to still get the contents into the target window, if we really needed to.
That isn't entirely the point though. Part of the issue is that the behaviour for creating a new context should be consistent with the behaviour for reusing an existing one. Another part is that for better or worse, the model we currently have is that provided OpenGL works at all, context_acquire() isn't supposed to fail. It may make sense to rethink that, but we have a lot more context_acquire() calls besides the one in swapchain_gl_present().
The background is that the target window can go away at any given point, and D3D is supposed to keep working when that happens. Modern versions of OpenGL/GLX can make a context current without a drawable, but originally the drawable was required. Provided FBOs are available current wined3d always renders offscreen and only needs an onscreen context for Present(), but in the past that was not the case either. (I.e., think Opengl 1.x or 2.x and "backbuffer" ORM.)
Thanks for the explanation, I see now.
So I will make wined3d_context_gl_init() create backup context as well if it fails to set pixel format (and maybe as well if wglCreateContext() fails?).