gl4es feature detection does not work reliably with EGL.
If a context already exists, gl4es can instead reliably detect
the underlying GLES features from the context itself.
This requires gl4es to be configured with:
-DNOEGL=ON -DNO_LOADER=ON -DNO_INIT_CONSTRUCTOR=ON
This also requires gl4es to have this fix: https://github.com/ptitSeb/gl4es/pull/271
Try lower MSAA level if the requested value isn't available
Closes#4471 and #4631
See merge request OpenMW/openmw!297
(cherry picked from commit b3db387512340a5e9a77427c2d7d9d88c2340056)
da0aef7a Retrieve SDL OpenGL attributes after context creation
a51e63b3 Try lower MSAA levels if OpenGL context doesn't have what we requested
c4e92a0a Update CHANGELOG.md
/home/elsid/dev/openmw/components/sdlutil/sdlgraphicswindow.cpp:23:8: warning: Call to virtual function during construction [clang-analyzer-optin.cplusplus.VirtualCall]
if(valid())
^
/home/elsid/dev/openmw/components/sdlutil/sdlgraphicswindow.cpp:23:8: note: This constructor of an object of type 'GraphicsWindowSDL2' has not returned when the virtual method was called
/home/elsid/dev/openmw/components/sdlutil/sdlgraphicswindow.cpp:23:8: note: Call to virtual function during construction
Since commit e8662bea31, we're using OSG functionality that contains an unfixed crash bug in version 3.2. The bug is fixed in version 3.4 (OSG commit 6351e5020371b0b72b300088a5c6772f58379b84)
