Mesa EGL

The current version of EGL in Mesa implements EGL 1.4. More information about EGL can be found at - -http://www.khronos.org/egl/.

+ +https://www.khronos.org/egl/.

The Mesa's implementation of EGL uses a driver architecture. The main library (libEGL) is window system neutral. It provides the EGL @@ -36,7 +44,7 @@ the driver for your hardware. For example

The main library and OpenGL is enabled by default. The first two options above enables OpenGL ES 1.x and 2.x. The last two -options enables the listed classic and and Gallium drivers respectively.

+options enables the listed classic and Gallium drivers respectively.

@@ -52,65 +60,62 @@ or more EGL drivers.

There are several options that control the build of EGL at configuration time

--enable-egl +
+
--enable-egl
+

By default, EGL is enabled. When disabled, the main library and the drivers will not be built.
-
--with-egl-driver-dir +
--with-egl-driver-dir
+

The directory EGL drivers should be installed to. If not specified, EGL drivers will be installed to ${libdir}/egl.
-
--enable-gallium-egl + -
Enable the optional egl_gallium driver.
- -
--with-egl-platforms +
--with-platforms
+

List the platforms (window systems) to support. Its argument is a comma -seprated string such as --with-egl-platforms=x11,drm. It decides +separated string such as --with-platforms=x11,drm. It decides the platforms a driver may support. The first listed platform is also used by -the main library to decide the native platform: the platform the EGL native -types such as EGLNativeDisplayType or -EGLNativeWindowType defined for.
+the main library to decide the native platform.

The available platforms are x11, drm, -fbdev, and gdi. The gdi platform can -only be built with SCons. Unless for special needs, the build system should +wayland, surfaceless, android, +and haiku. +The android platform can either be built as a system +component, part of AOSP, using Android.mk files, or +cross-compiled using appropriate configure options. +The haiku platform can only be built with SCons. +Unless for special needs, the build system should select the right platforms automatically.
-
--enable-gles1 and --enable-gles2 +
--enable-gles1
+
--enable-gles2
+

These options enable OpenGL ES support in OpenGL. The result is one big internal library that supports multiple APIs.
-
--enable-shared-glapi +
--enable-shared-glapi
+

By default, libGL has its own copy of libglapi. This options makes libGL use the shared libglapi. This is required if applications mix OpenGL and OpenGL ES.
-
--enable-openvg - -
OpenVG must be explicitly enabled by this option.
- -

Use EGL

@@ -124,70 +129,37 @@ mesa/demos repository.

There are several environment variables that control the behavior of EGL at runtime

EGL_DRIVERS_PATH - -
By default, the main library will look for drivers in the directory where -the drivers are installed to. This variable specifies a list of -colon-separated directories where the main library will look for drivers, in -addition to the default directory. This variable is ignored for setuid/setgid -binaries.
- -
This variable is usually set to test an uninstalled build. For example, one -may set
- -
```
-  $ export LD_LIBRARY_PATH=$mesa/lib
-  $ export EGL_DRIVERS_PATH=$mesa/lib/egl
-
```
- -
to test a build without installation
- -
EGL_DRIVER - -
This variable specifies a full path to or the name of an EGL driver. It -forces the specified EGL driver to be loaded. It comes in handy when one wants -to test a specific driver. This variable is ignored for setuid/setgid -binaries.
- -
EGL_PLATFORM +
+
EGL_PLATFORM
+

This variable specifies the native platform. The valid values are the same -as those for --with-egl-platforms. When the variable is not set, +as those for --with-platforms. When the variable is not set, the main library uses the first platform listed in ---with-egl-platforms as the native platform.
+--with-platforms as the native platform.

Extensions like EGL_MESA_drm_display define new functions to create displays for non-native platforms. These extensions are usually used by applications that support non-native platforms. Setting this variable is probably required only for some of the demos found in mesa/demo repository.
-
EGL_LOG_LEVEL +
EGL_LOG_LEVEL
+

This changes the log level of the main library and the drivers. The valid values are: debug, info, warning, and fatal.
-
EGL_SOFTWARE - -
For drivers that support both hardware and software rendering, setting this -variable to true forces the use of software rendering.
- -

+ +

EGL Drivers

egl_dri2 +
+
egl_dri2
+

This driver supports both x11 and drm platforms. It functions as a DRI driver loader. For x11 support, it talks to @@ -195,52 +167,17 @@ the X server directly using (XCB-)DRI2 protocol.

This driver can share DRI drivers with libGL.
-
egl_gallium - -
This driver is based on Gallium3D. It supports all rendering APIs and -hardwares supported by Gallium3D. It is the only driver that supports OpenVG. -The supported platforms are X11, DRM, FBDEV, and GDI.
- -
This driver comes with its own hardware drivers -(pipe_<hw>) and client API modules -(st_<api>).
- -
egl_glx - -
This driver provides a wrapper to GLX. It uses exclusively GLX to implement -the EGL API. It supports both direct and indirect rendering when the GLX does. -It is accelerated when the GLX is. As such, it cannot provide functions that -is not available in GLX or GLX extensions.
-

Packaging

The ABI between the main library and its drivers are not stable. Nor is -there a plan to stabilize it at the moment. Of the EGL drivers, -egl_gallium has its own hardware drivers and client API modules. -They are considered internal to egl_gallium and there is also no -stable ABI between them. These should be kept in mind when packaging for -distribution.

- -

Generally, egl_dri2 is preferred over egl_gallium -when the system already has DRI drivers. As egl_gallium is loaded -before egl_dri2 when both are available, egl_gallium -is disabled by default.

+there a plan to stabilize it at the moment.

Developers

The sources of the main library and the classic drivers can be found at -src/egl/. The sources of the egl state tracker can -be found at src/gallium/state_trackers/egl/.

- -

The suggested way to learn to write a EGL driver is to see how other drivers -are written. egl_glx should be a good reference. It works in any -environment that has GLX support, and it is simpler than most drivers.

The sources of the main library and drivers can be found at +src/egl/.

Lifetime of Display Resources

@@ -249,8 +186,8 @@ longer than the display that creates them.

In EGL, when a display is terminated through eglTerminate, all display resources should be destroyed. Similarly, when a thread is released -throught eglReleaseThread, all current display resources should be -released. Another way to destory or release resources is through functions +through eglReleaseThread, all current display resources should be +released. Another way to destroy or release resources is through functions such as eglDestroySurface or eglMakeCurrent.