Mesa EGL

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 @@ -19,96 +27,88 @@ API entry points and helper functions for use by the drivers. Drivers are dynamically loaded by the main library and most of the EGL API calls are directly dispatched to the drivers.

The driver in use decides the window system to support. For drivers that -support hardware rendering, there are usually multiple drivers supporting the -same window system. Each one of of them supports a certain range of graphics -cards.

The driver in use decides the window system to support.

Build EGL

-
Run configure with the desired state trackers and enable -the Gallium driver for your hardware. For example
+
Configure your build with the desired client APIs and enable +the driver for your hardware. For example:
```
-  $ ./configure --enable-gles-overlay --with-state-trackers=egl,vega --enable-gallium-intel
+$ meson configure \
+        -D egl=true \
+        -D gles1=true \
+        -D gles2=true \
+        -D dri-drivers=... \
+        -D gallium-drivers=...
 
```
-
The main library and OpenGL is enabled by default. The first option enables -OpenGL ES 1.x and 2.x. The egl state -tracker is needed by a number of EGL drivers. EGL drivers will be covered -later. The vega state tracker provides OpenVG -1.x.
+
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 Gallium drivers respectively.
+
Build and install Mesa as usual.

In the given example, it will build and install libEGL, -libGL, libGLESv1_CM, libGLESv2, -libOpenVG, and one or more EGL drivers.

+libGL, libGLESv1_CM, libGLESv2, and one +or more EGL drivers.

Configure Options

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

--enable-egl +
+
-D egl=true
+

By default, EGL is enabled. When disabled, the main library and the drivers will not be built.
-
--with-egl-driver-dir + -
The directory EGL drivers should be installed to. If not specified, EGL -drivers will be installed to ${libdir}/egl.
- -
--with-egl-platforms +
-D 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 -D 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.
- -

wayland

surfaceless

android

haiku

android

Android.mk

--with-state-trackers + -
The argument is a comma separated string. It is usually used to specify the -rendering APIs, such as OpenVG, to build. But it is also used to specify -egl state tracker that egl_gallium depends on.
+
-D gles1=true and -D gles2=true
+
-
--enable-gles-overlay - -
OpenGL and OpenGL ES are not controlled by ---with-state-trackers. OpenGL is always built. To build OpenGL -ES, this option must be explicitly given.
+
These options enable OpenGL ES support in OpenGL. The result is one big +internal library that supports multiple APIs.
-
--enable-gles1 and --enable-gles2 +
-D shared-glapi=true
+
-
Unlike --enable-gles-overlay, which builds one library for each -rendering API, these options enable OpenGL ES support in OpenGL. The result is -one big library that supports multiple APIs.
+
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.
-

Use EGL

@@ -122,100 +122,56 @@ 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.
- -
EGL_DRIVER - -
This variable specifies a full path to an EGL driver and 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_gallium dynamically loads hardware drivers and client API -modules found in EGL_DRIVERS_PATH. Thus, specifying this variable -alone is not sufficient for egl_gallium for uninstalled build.
- -
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 -D platforms=.... When the variable is not set, the main library uses the first platform listed in ---with-egl-platforms as the native platform
+-D 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_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, KMS, FBDEV, and GDI.
+
+
egl_dri2
+
-
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.
-

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

egl_dri2 +
This driver can share DRI drivers with libGL.
-
This driver supports the X Window System as its window system. It functions -as a DRI2 driver loader. Unlike egl_glx, it has no dependency on -libGL. It talks to the X server directly using DRI2 protocol.
+ + -
egl_dri +
Packaging
-
This driver lacks maintenance and does not build. It is similiar -to egl_dri2 in that it functions as a DRI(1) driver loader. But -unlike egl_dri2, it supports Linux framebuffer devices as its -window system and supports EGL_MESA_screen_surface extension. As DRI1 drivers -are phasing out, it might eventually be replaced by egl_dri2.
- -

The ABI between the main library and its drivers are not stable. Nor is +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

@@ -224,8 +180,8 @@ 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.

When a resource that is current to some thread is destroyed, the resource @@ -291,18 +247,6 @@ not be called with the sample display at the same time. If a driver has access to an EGLDisplay without going through the EGL APIs, the driver should as well lock the display before using it. -

TODOs

- -

Pass the conformance tests
Reference counting in main library?
Mixed use of OpenGL, OpenGL ES 1.1, and OpenGL ES 2.0 is supported. But -which one of libGL.so, libGLESv1_CM.so, and -libGLESv2.so should an application link to? Bad things may happen -when, say, an application is linked to libGLESv2.so and -libcairo, which is linked to libGL.so instead.

- +