Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 1 | <html> |
| 2 | |
| 3 | <head><title>Mesa FAQ</title></head> |
| 4 | |
Brian Paul | 36da045 | 2005-01-20 03:55:10 +0000 | [diff] [blame] | 5 | <link rel="stylesheet" type="text/css" href="mesa.css"></head> |
| 6 | |
| 7 | <BODY> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 8 | |
| 9 | |
| 10 | <center> |
| 11 | <h1>Mesa Frequently Asked Questions</h1> |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 12 | Last updated: 17 November 2004 |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 13 | </center> |
| 14 | |
| 15 | <br> |
| 16 | <br> |
| 17 | <h2>Index</h2> |
| 18 | <a href="#part1">1. High-level Questions and Answers</a> |
| 19 | <br> |
| 20 | <a href="#part2">2. Compilation and Installation Problems</a> |
| 21 | <br> |
| 22 | <a href="#part3">3. Runtime / Rendering Problems</a> |
| 23 | <br> |
| 24 | <a href="#part4">4. Developer Questions</a> |
| 25 | <br> |
| 26 | <br> |
| 27 | <br> |
| 28 | |
| 29 | |
| 30 | |
| 31 | <a name="part1"> |
| 32 | </a><h1><a name="part1">1. High-level Questions and Answers</a></h1> |
| 33 | |
| 34 | <h2><a name="part1">1.1 What is Mesa?</a></h2> |
| 35 | <p> |
| 36 | <a name="part1">Mesa is an open-source implementation of the OpenGL specification. |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 37 | OpenGL is a programming library for writing interactive 3D applications. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 38 | See the </a><a href="http://www.opengl.org/">OpenGL website</a> for more |
| 39 | information. |
| 40 | </p> |
| 41 | <p> |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 42 | Mesa 5.x supports the OpenGL 1.4 specification. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 43 | </p> |
| 44 | |
| 45 | |
| 46 | <h2>1.2 Does Mesa support/use graphics hardware?</h2> |
| 47 | <p> |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 48 | Yes. Specifically, Mesa serves as the OpenGL core for the open-source |
| 49 | XFree86/DRI OpenGL drivers. See the <a href="http://dri.sf.net/">DRI |
| 50 | website</a> for more information. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 51 | </p> |
| 52 | <p> |
| 53 | There have been other hardware drivers for Mesa over the years (such as |
| 54 | the 3Dfx Glide/Voodoo driver, an old S3 driver, etc) but the DRI drivers |
| 55 | are the modern ones. |
| 56 | </p> |
| 57 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 58 | <h2>1.3 What purpose does Mesa serve today?</h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 59 | <p> |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 60 | Hardware-accelerated OpenGL implementations are available for most popular |
| 61 | operating systems today. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 62 | Still, Mesa serves at least these purposes: |
| 63 | </p> |
| 64 | <ul> |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 65 | <li>Mesa is used as the core of the open-source XFree86/DRI hardware drivers. |
| 66 | </li> |
| 67 | <li>Mesa is quite portable and allows OpenGL to be used on systems |
| 68 | that have no other OpenGL solution. |
| 69 | </li> |
| 70 | <li>Software rendering with Mesa serves as a reference for validating the |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 71 | hardware drivers. |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 72 | </li> |
| 73 | <li>A software implementation of OpenGL is useful for experimentation, |
| 74 | such as testing new rendering techniques. |
| 75 | </li> |
| 76 | <li>Mesa can render images with deep color channels: 16-bit integer |
| 77 | and 32-bit floating point color channels are supported. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 78 | This capability is only now appearing in hardware. |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 79 | </li> |
| 80 | <li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 81 | changed for special needs (hardware limits are hard to overcome). |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 82 | </li> |
| 83 | </ul> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 84 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 85 | |
| 86 | <h2>1.4 What's the difference between"Stand-Alone" Mesa and the DRI drivers?</h2> |
| 87 | <p> |
| 88 | <em>Stand-alone Mesa</em> is the original incarnation of Mesa. |
| 89 | On systems running the X Window System, it does all its rendering through |
| 90 | the Xlib API. |
| 91 | <ul> |
| 92 | <li>The GLX API is supported, but it's really just an emulation of the |
| 93 | real thing. |
| 94 | <li>The GLX wire protocol is not supported and there's no OpenGL extension |
| 95 | loaded by the X server. |
| 96 | <li>There is no hardware acceleration. |
| 97 | <li>The OpenGL library, libGL.so, contains everything (the programming API, |
| 98 | the GLX functions and all the rendering code). |
| 99 | </ul> |
| 100 | </p> |
| 101 | <p> |
| 102 | Alternately, Mesa acts as the core for a number of OpenGL hardware drivers |
| 103 | within the DRI (Direct Rendering Infrastructure): |
| 104 | <ul> |
| 105 | <li>The libGL.so library provides the GL and GLX API functions, a GLX |
| 106 | protocol encoder, and a device driver loader. |
| 107 | <li>The device driver modules (such as r200_dri.so) contain a built-in |
| 108 | copy of the core Mesa code. |
| 109 | <li>The X server loads the GLX module. |
| 110 | The GLX module decodes incoming GLX protocol and dispatches the commands |
| 111 | to a rendering module. |
| 112 | For the DRI, this module is basically a software Mesa renderer. |
| 113 | </ul> |
| 114 | |
| 115 | |
| 116 | |
| 117 | <h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?</h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 118 | <p> |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 119 | You don't! A copy of the Mesa source code lives inside the XFree86/DRI source |
| 120 | tree and gets compiled into the individual DRI driver modules. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 121 | If you try to install Mesa over an XFree86/DRI installation, you'll lose |
Brian Paul | a376e33 | 2003-03-30 16:54:36 +0000 | [diff] [blame] | 122 | hardware rendering (because stand-alone Mesa's libGL.so is different than |
| 123 | the XFree86 libGL.so). |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 124 | </p> |
| 125 | <p> |
| 126 | The DRI developers will incorporate the latest release of Mesa into the |
| 127 | DRI drivers when the time is right. |
| 128 | </p> |
Brian Paul | 824a4fc | 2003-08-06 19:05:26 +0000 | [diff] [blame] | 129 | <p> |
| 130 | To upgrade, either look for a new release of <a href="http://www.xfree86.org" |
| 131 | target="_parent">XFree86</a> or visit the |
| 132 | <a href="http://dri.sf.net" target="_parent">DRI website</a> to see |
| 133 | if there's newer drivers. |
| 134 | </p> |
| 135 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 136 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 137 | <h2>1.6 Are there other open-source implementations of OpenGL?</h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 138 | <p> |
Brian Paul | 7df4f95 | 2003-11-25 21:13:26 +0000 | [diff] [blame] | 139 | Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html" |
| 140 | target="_parent"> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 141 | OpenGL Sample Implemenation (SI)</a> is available. |
| 142 | The SI was written during the time that OpenGL was originally designed. |
| 143 | Unfortunately, development of the SI has stagnated. |
| 144 | Mesa is much more up to date with modern features and extensions. |
| 145 | </p> |
Brian Paul | 186d4d8 | 2004-04-27 12:55:08 +0000 | [diff] [blame] | 146 | |
| 147 | <p> |
| 148 | <a href="http://ogl-es.sourceforge.net" target="_parent">Vincent</a> is |
| 149 | an open-source implementation of OpenGL ES for mobile devices. |
| 150 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 151 | <p> |
Brian Paul | 7df4f95 | 2003-11-25 21:13:26 +0000 | [diff] [blame] | 152 | <a href="http://www.dsbox.com/minigl.html" target="_parent">miniGL</a> |
| 153 | is a subset of OpenGL for PalmOS devices. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 154 | |
Brian Paul | 7df4f95 | 2003-11-25 21:13:26 +0000 | [diff] [blame] | 155 | <p> |
| 156 | <a href="http://fabrice.bellard.free.fr/TinyGL/" |
| 157 | target="_parent">TinyGL</a> is a subset of OpenGL. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 158 | </p> |
Brian Paul | 7df4f95 | 2003-11-25 21:13:26 +0000 | [diff] [blame] | 159 | |
| 160 | <p> |
| 161 | <a href="http://softgl.studierstube.org/" target="_parent">SoftGL</a> |
| 162 | is an OpenGL subset for mobile devices. |
| 163 | </p> |
| 164 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 165 | <p> |
Brian Paul | acbc1e0 | 2003-11-26 18:10:31 +0000 | [diff] [blame] | 166 | <a href="http://chromium.sourceforge.net/" target="_parent">Chromium</a> |
| 167 | isn't a conventional OpenGL implementation (it's layered upon OpenGL), |
| 168 | but it does export the OpenGL API. It allows tiled rendering, sort-last |
| 169 | rendering, etc. |
| 170 | </p> |
| 171 | |
Brian Paul | acbc1e0 | 2003-11-26 18:10:31 +0000 | [diff] [blame] | 172 | <p> |
| 173 | There may be other open OpenGL implementations, but Mesa is the most |
| 174 | popular and feature-complete. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 175 | </p> |
| 176 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 177 | |
| 178 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 179 | <br> |
| 180 | <br> |
| 181 | |
| 182 | |
| 183 | <a name="part2"> |
| 184 | </a><h1><a name="part2">2. Compilation and Installation Problems</a></h1> |
| 185 | |
| 186 | |
| 187 | <h2><a name="part2">2.1 What's the easiest way to install Mesa?</a></h2> |
| 188 | <p> |
| 189 | <a name="part2">If you're using a Linux-based system, your distro CD most likely already |
| 190 | has Mesa packages (like RPM or DEB) which you can easily install. |
| 191 | </a></p> |
| 192 | |
| 193 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 194 | <h2><a name="part2">2.2 Running <code>configure; make</code> doesn't Work</a></h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 195 | <p> |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 196 | Mesa no longer supports GNU autoconf/automake. Why? |
| 197 | <ul> |
| 198 | <li>It seemed to seldom work on anything but Linux |
| 199 | <li>The config files were hard to maintain and hard to understand |
| 200 | <li>libtool caused a lot of grief |
| 201 | </ul> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 202 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 203 | <p> |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 204 | Now, Mesa again uses a conventional Makefile system (as it did originally). |
| 205 | Basically, each Makefile in the tree includes one of the configuration |
| 206 | files from the config/ directory. |
| 207 | The config files specify all the variables for a variety of popular systems. |
| 208 | </p> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 209 | |
| 210 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 211 | <h2><a name="part2">2.3 I get undefined symbols such as bgnpolygon, v3f, etc...</a></h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 212 | <p> |
| 213 | <a name="part2">You're application is written in IRIS GL, not OpenGL. |
| 214 | IRIS GL was the predecessor to OpenGL and is a different thing (almost) |
| 215 | entirely. |
| 216 | Mesa's not the solution. |
| 217 | </a></p> |
| 218 | |
| 219 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 220 | <h2><a name="part2">2.4 Where is the GLUT library?</a></h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 221 | <p> |
| 222 | <a name="part2">GLUT (OpenGL Utility Toolkit) is in the separate MesaDemos-x.y.z.tar.gz file. |
| 223 | If you don't already have GLUT installed, you should grab the MesaDemos |
| 224 | package and unpack it before compiling Mesa. |
| 225 | </a></p> |
| 226 | |
| 227 | |
| 228 | |
Brian Paul | 65b7905 | 2004-11-22 17:49:15 +0000 | [diff] [blame] | 229 | <h2><a name="part2">2.5 What's the proper place for the libraries and headers?</a></h2> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 230 | <p> |
| 231 | <a name="part2">On Linux-based systems you'll want to follow the |
Brian Paul | fc528e2 | 2003-12-31 20:59:51 +0000 | [diff] [blame] | 232 | </a><a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html" |
| 233 | target="_parent">Linux ABI</a> standard. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 234 | Basically you'll want the following: |
| 235 | </p> |
| 236 | <ul> |
| 237 | <li>/usr/include/GL/gl.h - the main OpenGL header |
| 238 | </li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header |
| 239 | </li><li>/usr/include/GL/glx.h - the OpenGL GLX header |
| 240 | </li><li>/usr/include/GL/glext.h - the OpenGL extensions header |
| 241 | </li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header |
| 242 | </li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header |
| 243 | </li><li>/usr/lib/libGL.so - a symlink to libGL.so.1 |
| 244 | </li><li>/usr/lib/libGL.so.1 - a symlink to libGL.so.1.xyz |
| 245 | </li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the |
| 246 | Mesa version number. |
| 247 | </li><li>/usr/lib/libGLU.so - a symlink to libGLU.so.1 |
| 248 | </li><li>/usr/lib/libGLU.so.1 - a symlink to libGLU.so.1.3.xyz |
| 249 | </li><li>/usr/lib/libGLU.so.xyz - the OpenGL Utility library. xyz denotes the Mesa |
| 250 | version number. |
| 251 | </li></ul> |
| 252 | <p> |
| 253 | After installing XFree86 and the DRI drivers, some of these files |
| 254 | may be symlinks into the /usr/X11R6/ tree. |
| 255 | </p> |
| 256 | <p> |
| 257 | The old-style Makefile system doesn't install the Mesa libraries; it's |
| 258 | up to you to copy them (and the headers) to the right place. |
| 259 | </p> |
| 260 | <p> |
| 261 | The GLUT header and library should go in the same directories. |
| 262 | </p> |
| 263 | <br> |
| 264 | <br> |
| 265 | |
| 266 | |
| 267 | <a name="part3"> |
| 268 | </a><h1><a name="part3">3. Runtime / Rendering Problems</a></h1> |
| 269 | |
| 270 | <h2><a name="part3">3.1 Rendering is slow / why isn't my graphics hardware being used?</a></h2> |
| 271 | <p> |
| 272 | <a name="part3">Stand-alone Mesa (downloaded as MesaLib-x.y.z.tar.gz) doesn't have any |
| 273 | support for hardware acceleration (with the exception of the 3DFX Voodoo |
| 274 | driver). |
| 275 | </a></p> |
| 276 | <p> |
| 277 | <a name="part3">What you really want is a DRI or NVIDIA (or another vendor's OpenGL) driver |
| 278 | for your particular hardware. |
| 279 | </a></p> |
| 280 | <p> |
| 281 | <a name="part3">You can run the <code>glxinfo</code> program to learn about your OpenGL |
| 282 | library. |
| 283 | Look for the GL_VENDOR and GL_RENDERER values. |
| 284 | That will identify who's OpenGL library you're using and what sort of |
| 285 | hardware it has detected. |
| 286 | </a></p> |
| 287 | <p> |
| 288 | <a name="part3">If your DRI-based driver isn't working, go to the |
Brian Paul | fc528e2 | 2003-12-31 20:59:51 +0000 | [diff] [blame] | 289 | </a><a href="http://dri.sf.net/" target="_parent">DRI website</a> for trouble-shooting information. |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 290 | </p> |
| 291 | |
| 292 | |
| 293 | <h2>3.2 I'm seeing errors in depth (Z) buffering. Why?</h2> |
| 294 | <p> |
| 295 | Make sure the ratio of the far to near clipping planes isn't too great. |
| 296 | Look |
Brian Paul | fc528e2 | 2003-12-31 20:59:51 +0000 | [diff] [blame] | 297 | <a href="http://www.sgi.com/software/opengl/advanced97/notes/node18.html" |
| 298 | target="_parent"> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 299 | here</a> for details. |
| 300 | </p> |
| 301 | <p> |
| 302 | Mesa uses a 16-bit depth buffer by default which is smaller and faster |
| 303 | to clear than a 32-bit buffer but not as accurate. |
| 304 | If you need a deeper you can modify the parameters to |
| 305 | <code> glXChooseVisual</code> in your code. |
| 306 | </p> |
| 307 | |
| 308 | |
| 309 | <h2>3.3 Why Isn't depth buffering working at all?</h2> |
| 310 | <p> |
| 311 | Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG |
| 312 | environment variable it will warn you about trying to enable depth testing |
| 313 | when you don't have a depth buffer. |
| 314 | </p> |
| 315 | <p>Specifically, make sure <code>glutInitDisplayMode</code> is being called |
| 316 | with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being |
| 317 | called with a non-zero value for GLX_DEPTH_SIZE. |
| 318 | </p> |
| 319 | <p>This discussion applies to stencil buffers, accumulation buffers and |
| 320 | alpha channels too. |
| 321 | </p> |
| 322 | |
| 323 | |
| 324 | <h2>3.4 Why does glGetString() always return NULL?</h2> |
| 325 | <p> |
| 326 | Be sure you have an active/current OpenGL rendering context before |
| 327 | calling glGetString. |
| 328 | </p> |
| 329 | |
| 330 | |
| 331 | <h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels</h2> |
| 332 | <p> |
| 333 | If you're trying to draw a filled region by using GL_POINTS or GL_LINES |
| 334 | and seeing holes or gaps it's because of a float-to-int rounding problem. |
| 335 | But this is not a bug. |
| 336 | See Appendix H of the OpenGL Programming Guide - "OpenGL Correctness Tips". |
| 337 | Basically, applying a translation of (0.375, 0.375, 0.0) to your coordinates |
| 338 | will fix the problem. |
| 339 | </p> |
| 340 | |
| 341 | <br> |
| 342 | <br> |
| 343 | |
| 344 | |
| 345 | <a name="part4"> |
| 346 | </a><h1><a name="part4">4. Developer Questions</a></h1> |
| 347 | |
| 348 | <h2><a name="part4">4.1 How can I contribute?</a></h2> |
| 349 | <p> |
| 350 | <a name="part4">First, join the Mesa3d-dev mailing list. That's where Mesa development |
| 351 | is discussed. |
| 352 | </a></p> |
| 353 | <p> |
Brian Paul | fc528e2 | 2003-12-31 20:59:51 +0000 | [diff] [blame] | 354 | <a name="part4">The </a><a href="http://www.opengl.org/developers/documentation/specs.html" target="_parent"> |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 355 | OpenGL Specification</a> is the bible for OpenGL implemention work. |
| 356 | You should read it. |
| 357 | </p> |
| 358 | <p>Most of the Mesa development work involves implementing new OpenGL |
| 359 | extensions, writing hardware drivers (for the DRI), and code optimization. |
| 360 | </p> |
| 361 | |
| 362 | <h2>4.2 How do I write a new device driver?</h2> |
| 363 | <p> |
| 364 | Unfortunately, writing a device driver isn't easy. |
| 365 | It requires detailed understanding of OpenGL, the Mesa code, and your |
| 366 | target hardware/operating system. |
| 367 | 3D graphics are not simple. |
| 368 | </p> |
| 369 | <p> |
| 370 | The best way to get started is to use an existing driver as your starting |
| 371 | point. |
| 372 | For a software driver, the X11 and OSMesa drivers are good examples. |
| 373 | For a hardware driver, the Radeon and R200 DRI drivers are good examples. |
| 374 | </p> |
| 375 | <p>The DRI website has more information about writing hardware drivers. |
| 376 | The process isn't well document because the Mesa driver interface changes |
| 377 | over time, and we seldome have spare time for writing documentation. |
| 378 | That being said, many people have managed to figure out the process. |
| 379 | </p> |
| 380 | <p> |
| 381 | Joining the appropriate mailing lists and asking questions (and searching |
| 382 | the archives) is a good way to get information. |
| 383 | </p> |
| 384 | |
| 385 | |
Brian Paul | fc528e2 | 2003-12-31 20:59:51 +0000 | [diff] [blame] | 386 | <h2>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa and/or the DRI drivers?</h2> |
| 387 | <p> |
| 388 | The <a href="http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt" target="_parent">specification for the extension</a> |
| 389 | indicates that there are intellectual property (IP) and/or patent issues |
| 390 | to be dealt with. |
| 391 | </p> |
| 392 | <p>We've been unsucessful in getting a response from S3 (or whoever owns |
| 393 | the IP nowadays) to indicate whether or not an open source project can |
| 394 | implement the extension (specifically the compression/decompression |
| 395 | algorithms). |
| 396 | </p> |
| 397 | <p> |
| 398 | Until we can get official permission to do so, this extension will not |
| 399 | be implemented in Mesa. |
| 400 | </p> |
| 401 | |
| 402 | |
Brian Paul | 0b27ace | 2003-03-08 17:38:57 +0000 | [diff] [blame] | 403 | </body> |
| 404 | </html> |