mesa/docs/opengles.rst

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OpenGL ES
=========
Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0. More information about
OpenGL ES can be found at https://www.khronos.org/opengles/.
OpenGL ES depends on a working EGL implementation. Please refer to
:doc:`Mesa EGL <egl>` for more information about EGL.
Build the Libraries
-------------------
#. Run ``meson configure`` with ``-D gles1=true -D gles2=true`` and
enable the Gallium driver for your hardware.
#. Build and install Mesa as usual.
Alternatively, if XCB-DRI2 is installed on the system, one can use
``egl_dri2`` EGL driver with OpenGL|ES-enabled DRI drivers
#. Run ``meson configure`` with ``-D gles1=true -D gles2=true``.
#. Build and install Mesa as usual.
Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or
more EGL drivers for your hardware.
Run the Demos
-------------
There are some demos in ``mesa/demos`` repository.
Developers
----------
Dispatch Table
~~~~~~~~~~~~~~
OpenGL ES has an additional indirection when dispatching functions
::
Mesa: glFoo() --> _mesa_Foo()
OpenGL ES: glFoo() --> _es_Foo() --> _mesa_Foo()
The indirection serves several purposes
- When a function is in Mesa and the type matches, it checks the
arguments and calls the Mesa function.
- When a function is in Mesa but the type mismatches, it checks and
converts the arguments before calling the Mesa function.
- When a function is not available in Mesa, or accepts arguments that
are not available in OpenGL, it provides its own implementation.
Other than the last case, OpenGL ES uses ``APIspec.xml`` to generate
functions to check and/or converts the arguments.