This extension allows the user to specify whether a full flush is performed when making a context not current.
The only way to set this currently is at context creation, so this patch provides that functionality.
Defualt behaviour is set at FLUSH, as per the spec.
This patch does not contain the changes to WGL, appleGL or other platforms as I do not have access to GL 4.5 hardware on those platforms.
Full details on the use of KHR_context_flush_control can be found here:
https://www.opengl.org/registry/specs/KHR/context_flush_control.txt
- Don't create a temporary context first; this was probably due to Windows
needing one to get the address of wglCreateContextAttribsARB(), but that's
a unique quirk of WGL, and doesn't apply to glX. The glX spec explicitly says
you have to get a function pointer that works with any context from
glXGetProcAddress(), including when no context exists.
- Properly check for the GLX_ARB_create_context instead of just looking for a
non-NULL glXCreateContextAttribsARB()...some implementations, like Mesa,
never return NULL for function lookups (Mesa returns pointers into a jump
table that is filled out when the GL is initialized; since you can look up
functions before you have a valid context, it can't definitely say a function
isn't valid at that point).
Jonas Kulla
The configure script didn't differentiate between Linux and Android, unconditionally compiling in the unix implementation of SDL_sysfilesystem.c.
I'm probably one of the very few people building SDL for android using classic configure + standalone toolchain, so this has gone undetected all along.
