gl_headers.h is basically header_fixes.h done consequently. It contains
all OpenGL defines (and some typedefs) we need. We don't include GL
headers provided by the system anymore.
Some care has to be taken by certain windowing APIs including all of
gl.h anyway. Then the definitions could clash. Fortunately, redefining
preprocessor symbols to the same content is allowed and ignored. Also,
redefining typedefs to the same thing is allowed in C11. Apparently the
latter is not allowed in C99, so there is an imperfect attempt to avoid
the typedefs if required API symbols are apparently present already.
The nost risky part about this are the standard typedefs and GLAPIENTRY.
The latter is different only on win32 (and at least consistently so).
The typedefs are mostly based on stdint.h typedefs, which khrplatform.h
clumsily emulates on platforms which don't have it. The biggest
difference is that we define GLsizeiptr directly to ptrdiff_t, instead
of checking for the _WIN64 symbol and defining it to long or long long.
This also typedefs GLsync to __GLsync, just like the khronos headers.
Although symbols prefixed with __ are implementation reserved, khronos
also violates this rule, and having the same definition as khronos will
avoid problems on duplicate definitions.
We can simplify the build scripts too. The ios-gl check seems a bit
wrong now (what we really want to test for is EAGLContext), but I can't
test and thus can't improve it.
cuda_dynamic.h redefined two GL symbols; just include the new headers
directly instead.
So that the EGL code can use it too.
Also print the actual FB config ID, instead of nonsense. (I _think_ once
in the past a certain GLX implementation just used numeric config IDs
casted to EGLConfig - or at least that would explain this nonsense.)
Until now, we've used system-specific API (GLX, EGL, etc.) to retrieve
the depth of the default framebuffer. (We equal this to display depth
and use the determined depth for dithering.)
We can actually retrieve this value through standard GL API, and it
works everywhere (except GLES 2 of course). This simplifies everything a
great deal.
egl_helpers.c is empty now. But I expect that some EGL boilerplate will
be moved to it, so don't remove it yet.
Until now, we've let the windowing backend decide. But since they
usually require premultiplied alpha, and premultiplied alpha is easier
to handle, hardcode it.
Until now, we have tried to create a GL 3.0 context. The main reason for
this is that many Mesa-based drivers did not support anything better.
But some drivers (Mesa AMD) will not report a higher OpenGL version,
because their compatibility mode is restricted. While later GL features
are reported as extensions just fine, there doesn't seem to be a way to
determine or enable higher GLSL versions.
Add some more shitty hacks to try to deal with this messed up situation,
and try to probe each interesting GL version separately (starting with
3.3, then 3.2 etc.). Other backends might suffer from similar problems,
but these will have to deal with it on their own.
Probably fixes#2938, or maybe not.
Do this to make the license situation less confusing.
This change should be of no consequence, since LGPL is compatible with
GPL anyway, and making it LGPL-only does not restrict the use with GPL
code.
Additionally, the wording implies that this is allowed, and that we can
just remove the GPL part.
long is 64 bits on x86_64 on Linux, which means the check for the corner
case of computing the depth mask is wrong.
Also, X11 compositors seem to expect premultiplied alpha.
wm4