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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 |
| OpenGL ES can be found at <a href="http://www.khronos.org/opengles/" |
| 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 |
| <a href="egl.html">Mesa EGL</a> for more information about EGL.</p> |
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| <h2>Build the Libraries</h2> |
| <ol> |
| <li>Run <code>configure</code> with <code>--enable-gles-overlay</code> and enable the Gallium driver for your hardware.</li> |
| <li>Build and install Mesa as usual.</li> |
| </ol> |
| |
| Alternatively, if XCB-DRI2 is installed on the system, one can use |
| <code>egl_dri2</code> EGL driver with OpenGL|ES-enabled DRI drivers |
| |
| <ol> |
| <li>Run <code>configure</code> with <code>--enable-gles1 --enable-gles2</code>.</li> |
| <li>Build and install Mesa as usual.</li> |
| </ol> |
| |
| <p>Both methods will install libGLESv1_CM, libGLESv2, libEGL, and one or more |
| 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 |
| your build. For example,</p> |
| |
| <pre> |
| $ cd progs/egl/eglut |
| $ make |
| $ cd ../opengles1 |
| $ make |
| $ ./torus_x11 |
| </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;"> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| </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> |
| Mesa: glFoo() --> _mesa_Foo() |
| OpenGL ES: glFoo() --> _es_Foo() --> _mesa_Foo() |
| </pre> |
| |
| <p>The indirection serves several purposes</p> |
| |
| <ul> |
| <li>When a function is in Mesa and the type matches, it checks the arguments and calls the Mesa function.</li> |
| <li>When a function is in Mesa but the type mismatches, it checks and converts the arguments before calling the Mesa function.</li> |
| <li>When a function is not available in Mesa, or accepts arguments that are not available in OpenGL, it provides its own implementation.</li> |
| </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> |
| </html> |
