forked from KolibriOS/kolibrios
71 lines
2.3 KiB
HTML
71 lines
2.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html lang="en">
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<head>
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<meta http-equiv="content-type" content="text/html; charset=utf-8">
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<title>OpenGL ES</title>
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<link rel="stylesheet" type="text/css" href="mesa.css">
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</head>
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<body>
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<div class="header">
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<h1>The Mesa 3D Graphics Library</h1>
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</div>
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<iframe src="contents.html"></iframe>
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<div class="content">
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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 information about
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OpenGL ES can be found at <a href="http://www.khronos.org/opengles/">
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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-gles1 --enable-gles2</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>mesa/demos</code> repository.</p>
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<h2>Developers</h2>
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<h3>Dispatch Table</h3>
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<p>OpenGL ES has an additional indirection when dispatching functions</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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</div>
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</body>
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</html>
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