81 lines
2.8 KiB
HTML
81 lines
2.8 KiB
HTML
<html>
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<title>OpenGL ES</title>
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<head><link rel="stylesheet" type="text/css" href="mesa.css"></head>
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<body>
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<h1>OpenGL ES</h1>
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<p>Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0. More informations about
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OpenGL ES can be found at <a href="http://www.khronos.org/opengles/"
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target="_parent"> http://www.khronos.org/opengles/</a>.</p>
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<p>OpenGL ES depends on a working EGL implementation. Please refer to
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<a href="egl.html">Mesa EGL</a> for more information about EGL.</p>
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<h2>Build the Libraries</h2>
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<ol>
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<li>Run <code>configure</code> with <code>--enable-gles-overlay</code> and enable the Gallium driver for your hardware.</li>
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<li>Build and install Mesa as usual.</li>
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</ol>
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Alternatively, if XCB-DRI2 is installed on the system, one can use
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<code>egl_dri2</code> EGL driver with OpenGL|ES-enabled DRI drivers
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<ol>
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<li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code>.</li>
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<li>Build and install Mesa as usual.</li>
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</ol>
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<p>Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or more
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EGL drivers for your hardware.</p>
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<h2>Run the Demos</h2>
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<p>There are some demos in <code>progs/egl/</code>. You can use them to test
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your build. For example,</p>
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<pre>
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$ cd progs/egl/eglut
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$ make
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$ cd ../opengles1
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$ make
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$ ./torus_x11
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</pre>
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<h2>Developers</h2>
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<h3>Internal Libraries</h3>
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<table border="1" style="text-align: center;">
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<tr><td>Library Name</td><td>Used By</td><td>Enabled</td><td>OpenGL</td><td>OpenGL ES 1.x</td><td>OpenGL ES 2.x</td></tr>
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<tr><td><code>libmesa.a</td><td>Classic DRI drivers</td><td>y</td><td>y</td><td>--enable-gles1</td><td>--enable-gles2</td></tr>
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<tr><td><code>libmesagallium.a</td><td>Gallium EGL and DRI drivers</td><td>y</td><td>y</td><td>--enable-gles1</td><td>--enable-gles2</td></tr>
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<tr><td><code>libes1gallium.a</td><td>Gallium EGL drivers</td><td>--enable-gles-overlay</td><td>n</td><td>y</td><td>n</td></tr>
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<tr><td><code>libes2gallium.a</td><td>Gallium EGL drivers</td><td>--enable-gles-overlay</td><td>n</td><td>n</td><td>y</td></tr>
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</table>
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<h3>Dispatch Table</h3>
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<p>OpenGL ES has an additional indirection when dispatching fucntions</p>
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<pre>
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Mesa: glFoo() --> _mesa_Foo()
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OpenGL ES: glFoo() --> _es_Foo() --> _mesa_Foo()
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</pre>
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<p>The indirection serves several purposes</p>
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<ul>
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<li>When a function is in Mesa and the type matches, it checks the arguments and calls the Mesa function.</li>
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<li>When a function is in Mesa but the type mismatches, it checks and converts the arguments before calling the Mesa function.</li>
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<li>When a function is not available in Mesa, or accepts arguments that are not available in OpenGL, it provides its own implementation.</li>
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</ul>
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<p>Other than the last case, OpenGL ES uses <code>APIspec.xml</code> to generate functions to check and/or converts the arguments.</p>
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</body>
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</html>
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