| 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|---|
| 2 | <html lang="en">
|
|---|
| 3 | <head>
|
|---|
| 4 | <meta http-equiv="content-type" content="text/html; charset=utf-8">
|
|---|
| 5 | <title>Mesa FAQ</title>
|
|---|
| 6 | <link rel="stylesheet" type="text/css" href="mesa.css">
|
|---|
| 7 | </head>
|
|---|
| 8 | <body>
|
|---|
| 9 |
|
|---|
| 10 | <div class="header">
|
|---|
| 11 | <h1>The Mesa 3D Graphics Library</h1>
|
|---|
| 12 | </div>
|
|---|
| 13 |
|
|---|
| 14 | <iframe src="contents.html"></iframe>
|
|---|
| 15 | <div class="content">
|
|---|
| 16 |
|
|---|
| 17 | <center>
|
|---|
| 18 | <h1>Mesa Frequently Asked Questions</h1>
|
|---|
| 19 | Last updated: 9 October 2012
|
|---|
| 20 | </center>
|
|---|
| 21 |
|
|---|
| 22 | <br>
|
|---|
| 23 | <br>
|
|---|
| 24 | <h2>Index</h2>
|
|---|
| 25 | <a href="#part1">1. High-level Questions and Answers</a>
|
|---|
| 26 | <br>
|
|---|
| 27 | <a href="#part2">2. Compilation and Installation Problems</a>
|
|---|
| 28 | <br>
|
|---|
| 29 | <a href="#part3">3. Runtime / Rendering Problems</a>
|
|---|
| 30 | <br>
|
|---|
| 31 | <a href="#part4">4. Developer Questions</a>
|
|---|
| 32 | <br>
|
|---|
| 33 | <br>
|
|---|
| 34 | <br>
|
|---|
| 35 |
|
|---|
| 36 |
|
|---|
| 37 |
|
|---|
| 38 | <h1 id="part1">1. High-level Questions and Answers</h1>
|
|---|
| 39 |
|
|---|
| 40 | <h2>1.1 What is Mesa?</h2>
|
|---|
| 41 | <p>
|
|---|
| 42 | Mesa is an open-source implementation of the OpenGL specification.
|
|---|
| 43 | OpenGL is a programming library for writing interactive 3D applications.
|
|---|
| 44 | See the <a href="https://www.opengl.org/">OpenGL website</a> for more
|
|---|
| 45 | information.
|
|---|
| 46 | </p>
|
|---|
| 47 | <p>
|
|---|
| 48 | Mesa 9.x supports the OpenGL 3.1 specification.
|
|---|
| 49 | </p>
|
|---|
| 50 |
|
|---|
| 51 |
|
|---|
| 52 | <h2>1.2 Does Mesa support/use graphics hardware?</h2>
|
|---|
| 53 | <p>
|
|---|
| 54 | Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
|
|---|
| 55 | drivers for X.org.
|
|---|
| 56 | </p>
|
|---|
| 57 | <ul>
|
|---|
| 58 | <li>See the <a href="https://dri.freedesktop.org/">DRI website</a>
|
|---|
| 59 | for more information.</li>
|
|---|
| 60 | <li>See <a href="https://01.org/linuxgraphics">01.org</a>
|
|---|
| 61 | for more information about Intel drivers.</li>
|
|---|
| 62 | <li>See <a href="https://nouveau.freedesktop.org">nouveau.freedesktop.org</a>
|
|---|
| 63 | for more information about Nouveau drivers.</li>
|
|---|
| 64 | <li>See <a href="https://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature</a>
|
|---|
| 65 | for more information about Radeon drivers.</li>
|
|---|
| 66 | </ul>
|
|---|
| 67 |
|
|---|
| 68 | <h2>1.3 What purpose does Mesa serve today?</h2>
|
|---|
| 69 | <p>
|
|---|
| 70 | Hardware-accelerated OpenGL implementations are available for most popular
|
|---|
| 71 | operating systems today.
|
|---|
| 72 | Still, Mesa serves at least these purposes:
|
|---|
| 73 | </p>
|
|---|
| 74 | <ul>
|
|---|
| 75 | <li>Mesa is used as the core of the open-source X.org DRI
|
|---|
| 76 | hardware drivers.
|
|---|
| 77 | </li>
|
|---|
| 78 | <li>Mesa is quite portable and allows OpenGL to be used on systems
|
|---|
| 79 | that have no other OpenGL solution.
|
|---|
| 80 | </li>
|
|---|
| 81 | <li>Software rendering with Mesa serves as a reference for validating the
|
|---|
| 82 | hardware drivers.
|
|---|
| 83 | </li>
|
|---|
| 84 | <li>A software implementation of OpenGL is useful for experimentation,
|
|---|
| 85 | such as testing new rendering techniques.
|
|---|
| 86 | </li>
|
|---|
| 87 | <li>Mesa can render images with deep color channels: 16-bit integer
|
|---|
| 88 | and 32-bit floating point color channels are supported.
|
|---|
| 89 | This capability is only now appearing in hardware.
|
|---|
| 90 | </li>
|
|---|
| 91 | <li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be
|
|---|
| 92 | changed for special needs (hardware limits are hard to overcome).
|
|---|
| 93 | </li>
|
|---|
| 94 | </ul>
|
|---|
| 95 |
|
|---|
| 96 |
|
|---|
| 97 | <h2>1.4 What's the difference between "Stand-Alone" Mesa and the DRI drivers?</h2>
|
|---|
| 98 | <p>
|
|---|
| 99 | <em>Stand-alone Mesa</em> is the original incarnation of Mesa.
|
|---|
| 100 | On systems running the X Window System it does all its rendering through
|
|---|
| 101 | the Xlib API:
|
|---|
| 102 | </p>
|
|---|
| 103 | <ul>
|
|---|
| 104 | <li>The GLX API is supported, but it's really just an emulation of the
|
|---|
| 105 | real thing.
|
|---|
| 106 | <li>The GLX wire protocol is not supported and there's no OpenGL extension
|
|---|
| 107 | loaded by the X server.
|
|---|
| 108 | <li>There is no hardware acceleration.
|
|---|
| 109 | <li>The OpenGL library, libGL.so, contains everything (the programming API,
|
|---|
| 110 | the GLX functions and all the rendering code).
|
|---|
| 111 | </ul>
|
|---|
| 112 | <p>
|
|---|
| 113 | Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
|
|---|
| 114 | within the DRI (Direct Rendering Infrastructure):
|
|---|
| 115 | <ul>
|
|---|
| 116 | <li>The libGL.so library provides the GL and GLX API functions, a GLX
|
|---|
| 117 | protocol encoder, and a device driver loader.
|
|---|
| 118 | <li>The device driver modules (such as r200_dri.so) contain a built-in
|
|---|
| 119 | copy of the core Mesa code.
|
|---|
| 120 | <li>The X server loads the GLX module.
|
|---|
| 121 | The GLX module decodes incoming GLX protocol and dispatches the commands
|
|---|
| 122 | to a rendering module.
|
|---|
| 123 | For the DRI, this module is basically a software Mesa renderer.
|
|---|
| 124 | </ul>
|
|---|
| 125 |
|
|---|
| 126 |
|
|---|
| 127 |
|
|---|
| 128 | <h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?</h2>
|
|---|
| 129 | <p>
|
|---|
| 130 | This wasn't easy in the past.
|
|---|
| 131 | Now, the DRI drivers are included in the Mesa tree and can be compiled
|
|---|
| 132 | separately from the X server.
|
|---|
| 133 | Just follow the Mesa <a href="install.html">compilation instructions</a>.
|
|---|
| 134 | </p>
|
|---|
| 135 |
|
|---|
| 136 |
|
|---|
| 137 | <h2>1.6 Are there other open-source implementations of OpenGL?</h2>
|
|---|
| 138 | <p>
|
|---|
| 139 | Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html">
|
|---|
| 140 | OpenGL Sample Implementation (SI)</a> is available.
|
|---|
| 141 | The SI was written during the time that OpenGL was originally designed.
|
|---|
| 142 | Unfortunately, development of the SI has stagnated.
|
|---|
| 143 | Mesa is much more up to date with modern features and extensions.
|
|---|
| 144 | </p>
|
|---|
| 145 |
|
|---|
| 146 | <p>
|
|---|
| 147 | <a href="https://sourceforge.net/projects/ogl-es/">Vincent</a> is
|
|---|
| 148 | an open-source implementation of OpenGL ES for mobile devices.
|
|---|
| 149 |
|
|---|
| 150 | <p>
|
|---|
| 151 | <a href="http://www.dsbox.com/minigl.html">miniGL</a>
|
|---|
| 152 | is a subset of OpenGL for PalmOS devices.
|
|---|
| 153 |
|
|---|
| 154 | <p>
|
|---|
| 155 | <a href="http://bellard.org/TinyGL/">TinyGL</a>
|
|---|
| 156 | is a subset of OpenGL.
|
|---|
| 157 | </p>
|
|---|
| 158 |
|
|---|
| 159 | <p>
|
|---|
| 160 | <a href="https://sourceforge.net/projects/softgl/">SoftGL</a>
|
|---|
| 161 | is an OpenGL subset for mobile devices.
|
|---|
| 162 | </p>
|
|---|
| 163 |
|
|---|
| 164 | <p>
|
|---|
| 165 | <a href="http://chromium.sourceforge.net/">Chromium</a>
|
|---|
| 166 | isn't a conventional OpenGL implementation (it's layered upon OpenGL),
|
|---|
| 167 | but it does export the OpenGL API. It allows tiled rendering, sort-last
|
|---|
| 168 | rendering, etc.
|
|---|
| 169 | </p>
|
|---|
| 170 |
|
|---|
| 171 | <p>
|
|---|
| 172 | <a href="http://www.ticalc.org/archives/files/fileinfo/361/36173.html">ClosedGL</a>
|
|---|
| 173 | is an OpenGL subset library for TI graphing calculators.
|
|---|
| 174 | </p>
|
|---|
| 175 |
|
|---|
| 176 | <p>
|
|---|
| 177 | There may be other open OpenGL implementations, but Mesa is the most
|
|---|
| 178 | popular and feature-complete.
|
|---|
| 179 | </p>
|
|---|
| 180 |
|
|---|
| 181 |
|
|---|
| 182 |
|
|---|
| 183 | <br>
|
|---|
| 184 | <br>
|
|---|
| 185 |
|
|---|
| 186 |
|
|---|
| 187 | <h1 id="part2">2. Compilation and Installation Problems</h1>
|
|---|
| 188 |
|
|---|
| 189 |
|
|---|
| 190 | <h2>2.1 What's the easiest way to install Mesa?</h2>
|
|---|
| 191 | <p>
|
|---|
| 192 | If you're using a Linux-based system, your distro CD most likely already
|
|---|
| 193 | has Mesa packages (like RPM or DEB) which you can easily install.
|
|---|
| 194 | </p>
|
|---|
| 195 |
|
|---|
| 196 |
|
|---|
| 197 | <h2>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...</h2>
|
|---|
| 198 | <p>
|
|---|
| 199 | You're application is written in IRIS GL, not OpenGL.
|
|---|
| 200 | IRIS GL was the predecessor to OpenGL and is a different thing (almost)
|
|---|
| 201 | entirely.
|
|---|
| 202 | Mesa's not the solution.
|
|---|
| 203 | </p>
|
|---|
| 204 |
|
|---|
| 205 |
|
|---|
| 206 | <h2>2.3 Where is the GLUT library?</h2>
|
|---|
| 207 | <p>
|
|---|
| 208 | GLUT (OpenGL Utility Toolkit) is no longer in the separate MesaGLUT-x.y.z.tar.gz file.
|
|---|
| 209 | If you don't already have GLUT installed, you should grab
|
|---|
| 210 | <a href="http://freeglut.sourceforge.net/">freeglut</a>.
|
|---|
| 211 | </p>
|
|---|
| 212 |
|
|---|
| 213 |
|
|---|
| 214 | <h2>2.4 Where is the GLw library?</h2>
|
|---|
| 215 | <p>
|
|---|
| 216 | GLw (OpenGL widget library) is now available from a separate <a href="https://cgit.freedesktop.org/mesa/glw/">git repository</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
|
|---|
| 217 | </p>
|
|---|
| 218 |
|
|---|
| 219 |
|
|---|
| 220 | <h2>2.5 What's the proper place for the libraries and headers?</h2>
|
|---|
| 221 | <p>
|
|---|
| 222 | On Linux-based systems you'll want to follow the
|
|---|
| 223 | <a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> standard.
|
|---|
| 224 | Basically you'll want the following:
|
|---|
| 225 | </p>
|
|---|
| 226 | <ul>
|
|---|
| 227 | <li>/usr/include/GL/gl.h - the main OpenGL header
|
|---|
| 228 | </li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header
|
|---|
| 229 | </li><li>/usr/include/GL/glx.h - the OpenGL GLX header
|
|---|
| 230 | </li><li>/usr/include/GL/glext.h - the OpenGL extensions header
|
|---|
| 231 | </li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header
|
|---|
| 232 | </li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header
|
|---|
| 233 | </li><li>/usr/lib/libGL.so - a symlink to libGL.so.1
|
|---|
| 234 | </li><li>/usr/lib/libGL.so.1 - a symlink to libGL.so.1.xyz
|
|---|
| 235 | </li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the
|
|---|
| 236 | Mesa version number.
|
|---|
| 237 | </li></ul>
|
|---|
| 238 | <p>
|
|---|
| 239 | When configuring Mesa, there are three autoconf options that affect the install
|
|---|
| 240 | location that you should take care with: <code>--prefix</code>,
|
|---|
| 241 | <code>--libdir</code>, and <code>--with-dri-driverdir</code>. To install Mesa
|
|---|
| 242 | into the system location where it will be available for all programs to use, set
|
|---|
| 243 | <code>--prefix=/usr</code>. Set <code>--libdir</code> to where your Linux
|
|---|
| 244 | distribution installs system libraries, usually either <code>/usr/lib</code> or
|
|---|
| 245 | <code>/usr/lib64</code>. Set <code>--with-dri-driverdir</code> to the directory
|
|---|
| 246 | where your Linux distribution installs DRI drivers. To find your system's DRI
|
|---|
| 247 | driver directory, try executing <code>find /usr -type d -name dri</code>. For
|
|---|
| 248 | example, if the <code>find</code> command listed <code>/usr/lib64/dri</code>,
|
|---|
| 249 | then set <code>--with-dri-driverdir=/usr/lib64/dri</code>.
|
|---|
| 250 | </p>
|
|---|
| 251 | <p>
|
|---|
| 252 | After determining the correct values for the install location, configure Mesa
|
|---|
| 253 | with <code>./configure --prefix=/usr --libdir=xxx --with-dri-driverdir=xxx</code>
|
|---|
| 254 | and then install with <code>sudo make install</code>.
|
|---|
| 255 | </p>
|
|---|
| 256 | <br>
|
|---|
| 257 | <br>
|
|---|
| 258 |
|
|---|
| 259 |
|
|---|
| 260 | <h1 id="part3">3. Runtime / Rendering Problems</h1>
|
|---|
| 261 |
|
|---|
| 262 | <h2>3.1 Rendering is slow / why isn't my graphics hardware being used?</h2>
|
|---|
| 263 | <p>
|
|---|
| 264 | If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
|
|---|
| 265 | (eg. classic swrast, softpipe or llvmpipe)
|
|---|
| 266 | </p>
|
|---|
| 267 | <p>
|
|---|
| 268 | You can run the <code>glxinfo</code> program to learn about your OpenGL
|
|---|
| 269 | library.
|
|---|
| 270 | Look for the <code>OpenGL vendor</code> and <code>OpenGL renderer</code> values.
|
|---|
| 271 | That will identify who's OpenGL library with which driver you're using and what sort of
|
|---|
| 272 | hardware it has detected.
|
|---|
| 273 | </p>
|
|---|
| 274 | <p>
|
|---|
| 275 | If you're using a hardware accelerated driver you want <code>direct rendering: Yes</code>.
|
|---|
| 276 | </p>
|
|---|
| 277 | <p>
|
|---|
| 278 | If your DRI-based driver isn't working, go to the
|
|---|
| 279 | <a href="https://dri.freedesktop.org/">DRI website</a> for trouble-shooting information.
|
|---|
| 280 | </p>
|
|---|
| 281 |
|
|---|
| 282 |
|
|---|
| 283 | <h2>3.2 I'm seeing errors in depth (Z) buffering. Why?</h2>
|
|---|
| 284 | <p>
|
|---|
| 285 | Make sure the ratio of the far to near clipping planes isn't too great.
|
|---|
| 286 | Look
|
|---|
| 287 | <a href="https://www.opengl.org/resources/faq/technical/depthbuffer.htm#0040">here</a>
|
|---|
| 288 | for details.
|
|---|
| 289 | </p>
|
|---|
| 290 | <p>
|
|---|
| 291 | Mesa uses a 16-bit depth buffer by default which is smaller and faster
|
|---|
| 292 | to clear than a 32-bit buffer but not as accurate.
|
|---|
| 293 | If you need a deeper you can modify the parameters to
|
|---|
| 294 | <code> glXChooseVisual</code> in your code.
|
|---|
| 295 | </p>
|
|---|
| 296 |
|
|---|
| 297 |
|
|---|
| 298 | <h2>3.3 Why Isn't depth buffering working at all?</h2>
|
|---|
| 299 | <p>
|
|---|
| 300 | Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG
|
|---|
| 301 | environment variable it will warn you about trying to enable depth testing
|
|---|
| 302 | when you don't have a depth buffer.
|
|---|
| 303 | </p>
|
|---|
| 304 | <p>Specifically, make sure <code>glutInitDisplayMode</code> is being called
|
|---|
| 305 | with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being
|
|---|
| 306 | called with a non-zero value for GLX_DEPTH_SIZE.
|
|---|
| 307 | </p>
|
|---|
| 308 | <p>This discussion applies to stencil buffers, accumulation buffers and
|
|---|
| 309 | alpha channels too.
|
|---|
| 310 | </p>
|
|---|
| 311 |
|
|---|
| 312 |
|
|---|
| 313 | <h2>3.4 Why does glGetString() always return NULL?</h2>
|
|---|
| 314 | <p>
|
|---|
| 315 | Be sure you have an active/current OpenGL rendering context before
|
|---|
| 316 | calling glGetString.
|
|---|
| 317 | </p>
|
|---|
| 318 |
|
|---|
| 319 |
|
|---|
| 320 | <h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels</h2>
|
|---|
| 321 | <p>
|
|---|
| 322 | If you're trying to draw a filled region by using GL_POINTS or GL_LINES
|
|---|
| 323 | and seeing holes or gaps it's because of a float-to-int rounding problem.
|
|---|
| 324 | But this is not a bug.
|
|---|
| 325 | See Appendix H of the OpenGL Programming Guide - "OpenGL Correctness Tips".
|
|---|
| 326 | Basically, applying a translation of (0.375, 0.375, 0.0) to your coordinates
|
|---|
| 327 | will fix the problem.
|
|---|
| 328 | </p>
|
|---|
| 329 |
|
|---|
| 330 | <br>
|
|---|
| 331 | <br>
|
|---|
| 332 |
|
|---|
| 333 |
|
|---|
| 334 | <h1 id="part4">4. Developer Questions</h1>
|
|---|
| 335 |
|
|---|
| 336 | <h2>4.1 How can I contribute?</h2>
|
|---|
| 337 | <p>
|
|---|
| 338 | First, join the <a href="lists.html">mesa-dev mailing list</a>.
|
|---|
| 339 | That's where Mesa development is discussed.
|
|---|
| 340 | </p>
|
|---|
| 341 | <p>
|
|---|
| 342 | The <a href="https://www.opengl.org/documentation">
|
|---|
| 343 | OpenGL Specification</a> is the bible for OpenGL implementation work.
|
|---|
| 344 | You should read it.
|
|---|
| 345 | </p>
|
|---|
| 346 | <p>Most of the Mesa development work involves implementing new OpenGL
|
|---|
| 347 | extensions, writing hardware drivers (for the DRI), and code optimization.
|
|---|
| 348 | </p>
|
|---|
| 349 |
|
|---|
| 350 | <h2>4.2 How do I write a new device driver?</h2>
|
|---|
| 351 | <p>
|
|---|
| 352 | Unfortunately, writing a device driver isn't easy.
|
|---|
| 353 | It requires detailed understanding of OpenGL, the Mesa code, and your
|
|---|
| 354 | target hardware/operating system.
|
|---|
| 355 | 3D graphics are not simple.
|
|---|
| 356 | </p>
|
|---|
| 357 | <p>
|
|---|
| 358 | The best way to get started is to use an existing driver as your starting
|
|---|
| 359 | point.
|
|---|
| 360 | For a classic hardware driver, the i965 driver is a good example.
|
|---|
| 361 | For a Gallium3D hardware driver, the r300g, r600g and the i915g are good examples.
|
|---|
| 362 | </p>
|
|---|
| 363 | <p>The DRI website has more information about writing hardware drivers.
|
|---|
| 364 | The process isn't well document because the Mesa driver interface changes
|
|---|
| 365 | over time, and we seldom have spare time for writing documentation.
|
|---|
| 366 | That being said, many people have managed to figure out the process.
|
|---|
| 367 | </p>
|
|---|
| 368 | <p>
|
|---|
| 369 | Joining the appropriate mailing lists and asking questions (and searching
|
|---|
| 370 | the archives) is a good way to get information.
|
|---|
| 371 | </p>
|
|---|
| 372 |
|
|---|
| 373 |
|
|---|
| 374 | <h2>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa?</h2>
|
|---|
| 375 | <p>
|
|---|
| 376 | The <a href="http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt">specification for the extension</a>
|
|---|
| 377 | indicates that there are intellectual property (IP) and/or patent issues
|
|---|
| 378 | to be dealt with.
|
|---|
| 379 | </p>
|
|---|
| 380 | <p>We've been unsuccessful in getting a response from S3 (or whoever owns
|
|---|
| 381 | the IP nowadays) to indicate whether or not an open source project can
|
|---|
| 382 | implement the extension (specifically the compression/decompression
|
|---|
| 383 | algorithms).
|
|---|
| 384 | </p>
|
|---|
| 385 | <p>
|
|---|
| 386 | In the mean time, a 3rd party <a href="https://dri.freedesktop.org/wiki/S3TC">
|
|---|
| 387 | plug-in library</a> is available.
|
|---|
| 388 | </p>
|
|---|
| 389 |
|
|---|
| 390 | </div>
|
|---|
| 391 | </body>
|
|---|
| 392 | </html>
|
|---|
