Attempt to fix threading issues that cause OBS to force-crash when
compiled with latest Xcode. There are two places where the new SDK
introduces a force-crash because operations are not happening on the
main thread: when we modify the context view to switch swap chains, and
when we resize a swap chain.
Instead of using just one context for all rendering, we create an
additional context for each swap chain, set each view once on
initialization, and switch contexts only in present to blit the final
framebuffer. This is an extra copy, but it's pretty hairy to optimize
away, and it's not worth potential regressions just to speed up Mac.
For resizing, we schedule the update code to run on the main thread from
the render thread. Ideally, we wouldn't have to round trip the logic
from main thread to graphics thread and back, but I don't think we want
to hack up the interface for this, especially since OpenGL will give way
to Metal soon enough.
glGetError() returns GL_INVALID_OPERATION during OBS shutdown when GL is
used on Windows. This change gives up after eight errors.
This could be avoided by stopping the graphics thread before window
destruction, but the shutdown code looks like it could be tricky to
reorder.
Code submissions have continually suffered from formatting
inconsistencies that constantly have to be addressed. Using
clang-format simplifies this by making code formatting more consistent,
and allows automation of the code formatting so that maintainers can
focus more on the code itself instead of code formatting.
The previous model stored a new FBO per texture width/height/format on
a array in the device struct. This allocated memory was only released
on gs_device_destroy (obs exit).
The new approach stores a FBO on gs_texture and the its info is
destroyed once the texture is deleted.
NOTE: In texture_setimage, I had to move variables to the top of the
scope because microsoft's C compiler will give the legacy C90 error of:
'illegal use of this type as an expression'.
To sum it up, microsoft's C compiler is still utter garbage.