X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;ds=inline;f=docs%2Fegl.html;h=fb15086679f5ba6310d063caa32fbe45e9060a68;hb=7c7a8a38e530a63717a2f374ae0574d8abf11e17;hp=30cbe0eaeddb03eb0dc707d079acc3770e2df73b;hpb=45dac0d82a5a69166e86dce77c2550f7512c541e;p=mesa.git diff --git a/docs/egl.html b/docs/egl.html index 30cbe0eaedd..fb15086679f 100644 --- a/docs/egl.html +++ b/docs/egl.html @@ -19,35 +19,31 @@ 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.
Run configure
with the desired state trackers and and enable
-the Gallium driver for your hardware. For example
Run configure
with the desired client APIs and enable
+the driver for your hardware. For example
- $ ./configure --with-state-trackers=egl,es,vega --enable-gallium-{swrast,intel} + $ ./configure --enable-gles2 --enable-openvg --enable-gallium-nouveau-
The main library will be enabled by default. The egl
state
-tracker is needed by a number of EGL drivers. EGL drivers will be covered
-later. The es state tracker provides OpenGL ES 1.x
-and 2.x and the vega state tracker provides OpenVG
-1.x.
The main library and OpenGL is enabled by default. The first option above +enables OpenGL ES 2.x. The second option enables +OpenVG.
+In the given example, it will build and install libEGL
,
-libGLESv1_CM
, libGLESv2
, libOpenVG
, and
-one or more EGL drivers.
libGL
, libGLESv1_CM
, libGLESv2
,
+libOpenVG
, and one or more EGL drivers.
${libdir}/egl
.
---with-egl-displays
+--with-egl-platforms
+
+List the platforms (window systems) to support. Its argument is a comma
+seprated string such as --with-egl-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.
List the window system(s) to support. It is by default x11
,
-which supports the X Window System. Its argument is a comma separated string
-like, for example, --with-egl-displays=x11,kms
. Because an EGL
-driver decides which window system to support, this example will enable two
-(sets of) EGL drivers. One supports the X window system and the other supports
-bare KMS (kernel modesetting).
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
+select the right platforms automatically.
--with-state-trackers
+--enable-gles1
and --enable-gles2
-The argument is a comma separated string. It is usually used to specify the
-rendering APIs, like OpenGL ES or OpenVG, to build. But it should be noted
-that a number of EGL drivers depend on the egl
state tracker.
-They will not be built without the egl
state tracker.
These options enable OpenGL ES support in OpenGL. The result is one big +internal library that supports multiple APIs.
--enable-gallium-swrast
+--enable-openvg
-This option is not specific to EGL. But if there is no driver for your -hardware, or you are experiencing problems with the hardware driver, you can -enable the swrast DRM driver. It is a dummy driver and EGL will fallback to -software rendering automatically.
+OpenVG must be explicitly enabled by this option.
--enable-gallium-egl
-The OpenGL state tracker is not built in the above example. It should be
-noted that the classic libGL
is not a state tracker and cannot be
-used with EGL (unless the EGL driver in use is egl_glx
). To build
-the OpenGL state tracker, one may append glx
to
---with-state-trackers
and manually build
-src/gallium/winsys/xlib/
.
Explicitly enable or disable egl_gallium
.
The demos for OpenGL ES and OpenVG can be found in progs/es1/
,
-progs/es2/
and progs/openvg/
. You can use them to
-test your build. For example,
- $ cd progs/es1/xegl - $ make - $ ./torus -+
There are demos for the client APIs supported by EGL. They can be found in +mesa/demos repository.
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 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.
+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_DISPLAY
+EGL_PLATFORM
-When EGL_DRIVER
is not set, the main library loads all
-EGL drivers that support a certain window system. EGL_DISPLAY
can
-be used to specify the window system and the valid values are, for example,
-x11
or kms
. When the variable is not set, the main
-library defaults the value to the first window system listed in
---with-egl-displays
at configuration time.
+
This variable specifies the native platform. The valid values are the same
+as those for --with-egl-platforms
. When the variable is not set,
+the main library uses the first platform listed in
+--with-egl-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.
There are two categories of EGL drivers: Gallium and classic.
+egl_dri2
-Gallium EGL drivers supports all rendering APIs specified in EGL 1.4. The
-support for optional EGL functions and EGL extensions is usually more complete
-than the classic ones. These drivers depend on the egl
state
-tracker to build. The available drivers are
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_<dpy>_i915
egl_<dpy>_i965
egl_<dpy>_radeon
egl_<dpy>_nouveau
egl_<dpy>_swrast
egl_<dpy>_vmwgfx
This driver can share DRI drivers with libGL
.
<dpy>
is given by --with-egl-displays
at
-configuration time. There will be one EGL driver for each combination of the
-displays listed and the hardware drivers enabled.
Classic EGL drivers, on the other hand, supports only OpenGL as its
-rendering API. They can be found under src/egl/drivers/
. There
-are 3 of them
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 @@ -205,32 +206,22 @@ 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.
egl_xdri
-
-This driver supports the X Window System as its window system. It functions
-as a DRI driver loader and can load DRI/DRI2/DRISW drivers. Unlike
-egl_glx
, it has no dependency on libGL
. It talks to
-the X server directly using DRI or DRI2 protocols. It also talks minimal GLX
-protocol for things like available visuals or fbconfigs. With direct access to
-the DRI drivers, it has the potential to support more EGL functions that are
-not possible with egl_glx
.
egl_dri
-
-This driver lacks maintenance and does not build. It is similiar
-to egl_xdri
in that it functions as a DRI driver loader. But
-unlike egl_xdri
, it supports Linux framebuffer devices as its
-window system and supports EGL_MESA_screen_surface extension. It loads only
-DRI1 drivers. As DRI1 drivers is phasing out, it might be better to rewrite
-the driver to support KMS and DRI2.
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.
To use the classic drivers, one must manually set EGL_DRIVER
at
-runtime.
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
+may either be disabled with --disable-gallium-egl
or packaged
+separately.
EGL_RENDER_BUFFER
In EGL, the color buffer a context should try to render to is decided by the
+binding surface. It should try to render to the front buffer if the binding
+surface has EGL_RENDER_BUFFER
set to
+EGL_SINGLE_BUFFER
; If the same context is later bound to a
+surface with EGL_RENDER_BUFFER
set to
+EGL_BACK_BUFFER
, the context should try to render to the back
+buffer. However, the context is allowed to make the final decision as to which
+color buffer it wants to or is able to render to.
For pbuffer surfaces, the render buffer is always
+EGL_BACK_BUFFER
. And for pixmap surfaces, the render buffer is
+always EGL_SINGLE_BUFFER
. Unlike window surfaces, EGL spec
+requires their EGL_RENDER_BUFFER
values to be honored. As a
+result, a driver should never set EGL_PIXMAP_BIT
or
+EGL_PBUFFER_BIT
bits of a config if the contexts created with the
+config won't be able to honor the EGL_RENDER_BUFFER
of pixmap or
+pbuffer surfaces.
It should also be noted that pixmap and pbuffer surfaces are assumed to be
+single-buffered, in that eglSwapBuffers
has no effect on them. It
+is desirable that a driver allocates a private color buffer for each pbuffer
+surface created. If the window system the driver supports has native pbuffers,
+or if the native pixmaps have more than one color buffers, the driver should
+carefully attach the native color buffers to the EGL surfaces, re-route them if
+required.
There is no defined behavior as to, for example, how
+glDrawBuffer
interacts with EGL_RENDER_BUFFER
. Right
+now, it is desired that the draw buffer in a client API be fixed for pixmap and
+pbuffer surfaces. Therefore, the driver is responsible to guarantee that the
+client API renders to the specified render buffer for pixmap and pbuffer
+surfaces.
EGLDisplay
MutexEGLDisplay
will be locked before calling any of the dispatch
+functions (well, except for GetProcAddress which does not take an
+EGLDisplay
). This guarantees that the same dispatch function will
+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.
+
EGL_DISPLAY
loads all
-drivers and might eat too much memory.glxinit.c
and sources from src/glx/x11/
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.