Go to file
Sam Lantinga 4b585e75d9 Fixed bug 4833 - Use EGL for X11?
Martin Fiedler

To be precise, this is about *desktop OpenGL* on X11. For OpenGL ES, EGL is already used (as it's the only way to get an OpenGL ES context), as Sylvain noted above.

To shine some light on why this is needed:
In 99% of all cases, using GLX on X11 is fine, even though it's effectively deprecated in favor of EGL [1]. However, there's at least one use case that *requires* the OpenGL context being created with EGL instead of GLX, and that's DRM_PRIME interoperability: The function glEGLImageTargetTexture2DOES simply doesn't work with GLX. (Currently, Mesa actually crashes when trying that.)
Some example code:
https://gist.github.com/kajott/d1b29c613be30893c855621edd1f212e
Runs on Intel and open-source AMD drivers just fine (others unconfirmed), but with #define USE_EGL 0 (i.e. forcing it to GLX), it crashes. The same happens when using SDL for window and context creation.

The good news is that most of the pieces for EGL support on X11 are already in place: SDL_egl.c is pretty complete (and used for desktop OpenGL on Wayland, for example), and SDL_x11opengl.c has the aforementioned OpenGL-ES-on-EGL support. However, when it comes to desktop OpenGL, it's hardcoded to fall back to GLX.

I'm not advocating to make EGL the default for desktop OpenGL on X11; don't fix what ain't broken. But something like an SDL_HINT_VIDEO_X11_FORCE_EGL would be very appreciated to make use cases like the above work with SDL.


[1] source: Eric Anholt, major Linux graphics stack developer, 7 years ago already - see last paragraph of https://www.phoronix.com/scan.php?page=news_item&px=MTE3MTI
2020-02-03 08:06:52 -08:00
VisualC Added new HIDAPI driver files to the Visual Studio project 2019-12-19 15:12:36 -08:00
VisualC-WinRT added SDL_strtokr() as a replacement for POSIX strtok_r (bug #4046.) 2019-11-20 20:40:50 +03:00
Xcode Fixed the hidapi Info.plist for submission to the Apple App Store 2020-02-03 00:51:35 -08:00
Xcode-iOS Added SDL_hidapi_steam.c to the iOS and tvOS dylib build targets 2020-01-29 20:09:14 -08:00
acinclude Added missing PKG_CONFIG macros 2019-03-16 17:39:15 -07:00
android-project Miscellaneous pending fixes 2020-01-29 20:09:08 -08:00
android-project-ant Added the old ant Android build project structure 2017-10-28 12:11:25 -07:00
build-scripts Updated SDL development builds to version 2.0.11 2019-09-22 10:37:16 -07:00
cmake hidapi: Add SDL_hidapi.c, allows support for multiple hidapi backends. 2019-07-31 12:20:55 -04:00
debian Updated copyright date for 2020 2020-01-16 20:49:25 -08:00
docs CMake: tabs to spaces in new parts of README-cmake.md 2019-09-23 18:30:22 -04:00
include Fixed bug 4833 - Use EGL for X11? 2020-02-03 08:06:52 -08:00
src Fixed bug 4833 - Use EGL for X11? 2020-02-03 08:06:52 -08:00
test On Mac OSX there are spurious hat events at program start, so skip these 2020-01-17 11:06:02 -08:00
visualtest test: unify all the command line usage logging. 2019-05-28 17:39:13 -04:00
wayland-protocols wayland: ask xdg-decoration protocol extension to use server-side decorations if possible. 2018-11-04 21:08:40 +01:00
.hgignore remove test/aclocal.m4 2019-08-03 12:49:50 +03:00
Android.mk There are lots of unused macros in the Steam controller code 2020-01-29 20:09:12 -08:00
BUGS.txt BUGS.txt: Changed mailing list link to discourse.libsdl.org. 2017-04-01 00:05:25 -04:00
CMakeLists.txt Fixed bug 4928 - CMakeLists.txt: put cmake package helpers in proper libdir 2020-01-06 07:06:58 -08:00
COPYING.txt Updated copyright date for 2020 2020-01-16 20:49:25 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt More HTTPS doc tweaks. 2017-02-16 16:59:07 -05:00
Makefile.in Add public APIs for creating a Metal view attached to an SDL window. Add SDL_metal.h. 2019-08-05 12:35:32 -03:00
Makefile.minimal Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
Makefile.os2 added SDL_strtokr() as a replacement for POSIX strtok_r (bug #4046.) 2019-11-20 20:40:50 +03:00
Makefile.pandora Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
Makefile.psp added SDL_strtokr() as a replacement for POSIX strtok_r (bug #4046.) 2019-11-20 20:40:50 +03:00
Makefile.wiz Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
README-SDL.txt More HTTPS changes in the documentation. 2017-02-16 16:52:03 -05:00
README.txt readme: correct webpage URL to use HTTPS. 2017-02-16 13:30:34 -05:00
SDL2.spec.in Fixed bug 4615 - RPM Build fails due to unpackaged files 2019-06-11 19:58:10 -07:00
SDL2Config.cmake Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Added a helper function SDL_LockTextureToSurface() 2019-09-30 20:58:44 +02:00
autogen.sh Don't use pushd/popd in autogen.sh; Ubuntu's /bin/sh doesn't support it. 2016-12-26 22:58:58 -05:00
cmake_uninstall.cmake.in Fixed bug 3867 - Can't find install_manifest.txt when running 'uninstall' target 2017-10-12 08:44:45 -07:00
configure Fixed bug 4357 - iosbuild.sh broken with SDL 2.0.9 2019-12-31 10:40:30 -08:00
configure.ac Fixed bug 4357 - iosbuild.sh broken with SDL 2.0.9 2019-12-31 10:40:30 -08:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 4544 - SDL2.m4 SDL2.framework patch made it impossible to fail detection 2019-03-16 18:45:10 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00

README.txt

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.


                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
https://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)