This mode should *not* be used by any new engines/code. If someone is going
to use it and says it works with the OpenGL output, please make them wear a
red uniform and beam them onto a remote planet.
Formerly, we required that the OpenGL mode was fixed at compile time. Now we
allow the code to work with whatever it is given at runtime.
It is still possible to force a context type on compile time.
This used to be used by Sword25. Since it is not supported by GLES and no
engine code uses it we drop support. Hopefully, this helps people to realize
they should not use that format in their engine.
Formerly we relied on static linkage. However, in the presense of modern
OpenGL (ES) implementations it is not easily identifable which library to link
against. For example, on Linux amd64 with nVidia drivers and SDL2 setup to
create a GLES 1.1 context one would need to link against libGL.so. However,
traditionally GLES 1.1 required to link against libGLESv1_CM.so. To prevent a
huge mess we simply resolve the OpenGL functions on run-time now and stop
linking against a static library (in most cases).
GLES support needs to be enabled manually on configure time for now.
Tizen changes have NOT been tested.
This gets rid of the feeling of the mouse sticking to black borders by using
the full output resolution as area for tracking game mouse movement. The same
behavior is present in plain SDL output with SDL2.
Subclasses of OpenGLGraphicsManager are now supposed to supply a refreshScreen
function which handles actual screen updating (for example, buffer swapping).
There might be various error flags and we need to clear all of them to get
precise error results. Thus, we need to call glGetError in a loop to achieve
that.
This is mostly aimed at old graphics chips. For example, wjp's old laptop
only supports 1024x1024 textures but has a 1280x800 screen. Switching to
fullscreen would create a bigger overlay than supported. Now it will get
limited to an smaller resolution and then scaled too.
Alternatively we could think of tiling surfaces into textures. But then
handling scaling would be more complicated since it might result in
artifacts on texture tile borders.
