Reload all GL state when toggling fullscreen on OS X

[Philip Taylor]

On OS X, switching from fullscreen to windowed mode apparently triggers errors like ogl_program_get_uniform_location(shader, "TextureMatrix1") returning negative values, and the textures disappear and everything goes black and grey and sometimes it crashes.

I guess the GL context state gets lost when toggling fullscreen, in which case we need to destroy and reload all our GL objects (textures, shaders, vertex buffers, framebuffers, etc) when switching.

[historic_bruno]

A similar problem occurs on Windows using SDL 1.2 instead of our custom implementation, see #935. Apparently it has been ​fixed in SDL 1.3, so that may be an alternative solution.

[Philip Taylor]

As far as I'm aware, SDL 1.3 is nowhere near release (and even further from being sufficiently widely available on Linux that we can rely on it as a dependency), so it may not be a viable solution.

[ben]

In 11752:

Disables broken window resizing and fullscreen toggling on OS X. Fixes #1381. Refs #741

[historic_bruno]

SDL 2.0 fixes resizing and fullscreen toggling on OS X (so far confirmed on 10.8.3, I'll try testing older versions). Even so, it might be nice to have a way to reload all GL state, but it's much less of a priority now.

[philip]

In 14016:

Refactor text renderer

Replace unifont with CFont and CFontManager, since the h_mgr interface was
needlessly inconvenient.

Load the font textures through CTextureManager, to support dynamic
reloading (e.g. when resetting GL state - see #741).

Add CFontMetrics as a convenient wrapper for code that just wants to
measure text.

Fixes #1117.

[historic_bruno]

This will be resolved by the use of SDL2 on OS X, which will be the default for A17.