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1<html> 2 3<head><title>Mesa FAQ</title></head> 4 5<BODY text="#000000" bgcolor="#55bbff" link="#111188"> 6 7 8<center> 9<h1>Mesa Frequently Asked Questions</h1> 10Last updated: 7 March 2003 11</center> 12 13<br> 14<br> 15<h2>Index</h2> 16<a href="#part1">1. High-level Questions and Answers</a> 17<br> 18<a href="#part2">2. Compilation and Installation Problems</a> 19<br> 20<a href="#part3">3. Runtime / Rendering Problems</a> 21<br> 22<a href="#part4">4. Developer Questions</a> 23<br> 24<br> 25<br> 26 27 28 29<a name="part1"> 30</a><h1><a name="part1">1. High-level Questions and Answers</a></h1> 31 32<h2><a name="part1">1.1 What is Mesa?</a></h2> 33<p> 34<a name="part1">Mesa is an open-source implementation of the OpenGL specification. 35OpenGL is a high-level programming library for interactive 3D graphics. 36See the </a><a href="http://www.opengl.org/">OpenGL website</a> for more 37information. 38</p> 39<p> 40Mesa 5.0.x supports the OpenGL 1.4 specification. 41</p> 42 43 44<h2>1.2 Does Mesa support/use graphics hardware?</h2> 45<p> 46Yes. Specifically, Mesa serves as the OpenGL core for the XFree86/DRI 47OpenGL drivers. See the <a href="http://dri.sf.net/">DRI website</a> for 48more information. 49</p> 50<p> 51There have been other hardware drivers for Mesa over the years (such as 52the 3Dfx Glide/Voodoo driver, an old S3 driver, etc) but the DRI drivers 53are the modern ones. 54</p> 55 56<h2>1.3 What purpose does (software) Mesa serve today?</h2> 57<p> 58Commercial, hardware-accelerated OpenGL implementations are available for 59many operating systems today. 60Still, Mesa serves at least these purposes: 61</p> 62<ul> 63<li>Mesa is used as the core of the XFree86/DRI hardware drivers. 64</li><li>Mesa is quite portable and allows OpenGL to be used on systems that have 65 no other OpenGL solution. 66</li><li>Software rendering with Mesa serves as a reference for validating the 67 hardware drivers. 68</li><li>A software implementation of OpenGL is useful for experimentation, such 69 as testing new rendering techniques. 70</li><li>Mesa can render images with deep color channels: 16-bit integer and 32-bit 71 floating point color channels are supported. 72 This capability is only now appearing in hardware. 73</li><li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be 74 changed for special needs (hardware limits are hard to overcome). 75</li></ul> 76 77<h2>1.4 How do I upgrade my DRI installation to use a new Mesa release?</h2> 78<p> 79You don't! The Mesa source code lives inside the XFree86/DRI source tree 80and gets compiled into the individual DRI driver modules. 81If you try to install Mesa over an XFree86/DRI installation, you'll lose 82hardware rendering (because Mesa's libGL.so is different than the XFree86 83libGL.so). 84</p> 85<p> 86The DRI developers will incorporate the latest release of Mesa into the 87DRI drivers when the time is right. 88</p> 89 90<h2>1.5 Are there other open-source implementations of OpenGL?</h2> 91<p> 92Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html"> 93OpenGL Sample Implemenation (SI)</a> is available. 94The SI was written during the time that OpenGL was originally designed. 95Unfortunately, development of the SI has stagnated. 96Mesa is much more up to date with modern features and extensions. 97</p> 98<p> 99<a href="http://www.dsbox.com/minigl.html">miniGL</a> is a subset of OpenGL 100for PalmOS devices. 101 102<a href="http://fabrice.bellard.free.fr/TinyGL/">TinyGL</a> is another 103subset of OpenGL. 104</p> 105<p> 106There may be others but Mesa is the most popular and feature-complete. 107</p> 108 109<br> 110<br> 111 112 113<a name="part2"> 114</a><h1><a name="part2">2. Compilation and Installation Problems</a></h1> 115 116 117<h2><a name="part2">2.1 What's the easiest way to install Mesa?</a></h2> 118<p> 119<a name="part2">If you're using a Linux-based system, your distro CD most likely already 120has Mesa packages (like RPM or DEB) which you can easily install. 121</a></p> 122 123 124<h2><a name="part2">2.2 Running <code>configure; make</code> Doesn't Work</a></h2> 125<p> 126<a name="part2">Unfortunately, the GNU autoconf/automake/libtool system doesn't seem to work 127too well on non GNU/Linux systems, even after installing gmake, gcc, etc. 128For that reason, Mesa's <b>old-style</b> makefile system is still included. 129The old-style system uses good old traditional Makefiles. Try the following: 130</a></p><pre><a name="part2"> cd Mesa-x.y.z 131 cp Makefile.X11 Makefile 132 make 133</a></pre> 134<a name="part2">You'll see a list of system configurations from which to choose. 135For example: 136</a><pre><a name="part2"> make linux-x86 137</a></pre> 138<p> 139<a name="part2">If you're experienced with GNU autoconf/automake/libtool and think you can help 140with maintence, contact the Mesa developers. 141FYI, the Mesa developers generally don't use the autoconf/automake system. 142We're especially annoyed with the fact that a +5000-line script (libtool) 143is needed to make shared libraries (ugh). 144</a></p> 145 146<h2><a name="part2">2.3 Mesa still doesn't compile</a></h2> 147<p> 148<a name="part2">If the old-style Makefile system doesn't work either, make sure you have 149the most recent version of Mesa. 150Otherwise, file a bug report or post to the Mesa3d-users mailing list. 151Give as much info as possible when describing your problem. 152</a></p> 153 154 155<h2><a name="part2">2.4 I get undefined symbols such as bgnpolygon, v3f, etc...</a></h2> 156<p> 157<a name="part2">You're application is written in IRIS GL, not OpenGL. 158IRIS GL was the predecessor to OpenGL and is a different thing (almost) 159entirely. 160Mesa's not the solution. 161</a></p> 162 163 164<h2><a name="part2">2.5 Where is the GLUT library?</a></h2> 165<p> 166<a name="part2">GLUT (OpenGL Utility Toolkit) is in the separate MesaDemos-x.y.z.tar.gz file. 167If you don't already have GLUT installed, you should grab the MesaDemos 168package and unpack it before compiling Mesa. 169</a></p> 170 171 172 173<h2><a name="part2">2.6 What's the proper place for the libraries and headers?</a></h2> 174<p> 175<a name="part2">On Linux-based systems you'll want to follow the 176</a><a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> 177standard. 178Basically you'll want the following: 179</p> 180<ul> 181<li>/usr/include/GL/gl.h - the main OpenGL header 182</li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header 183</li><li>/usr/include/GL/glx.h - the OpenGL GLX header 184</li><li>/usr/include/GL/glext.h - the OpenGL extensions header 185</li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header 186</li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header 187</li><li>/usr/lib/libGL.so - a symlink to libGL.so.1 188</li><li>/usr/lib/libGL.so.1 - a symlink to libGL.so.1.xyz 189</li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the 190Mesa version number. 191</li><li>/usr/lib/libGLU.so - a symlink to libGLU.so.1 192</li><li>/usr/lib/libGLU.so.1 - a symlink to libGLU.so.1.3.xyz 193</li><li>/usr/lib/libGLU.so.xyz - the OpenGL Utility library. xyz denotes the Mesa 194version number. 195</li></ul> 196<p> 197After installing XFree86 and the DRI drivers, some of these files 198may be symlinks into the /usr/X11R6/ tree. 199</p> 200<p> 201The old-style Makefile system doesn't install the Mesa libraries; it's 202up to you to copy them (and the headers) to the right place. 203</p> 204<p> 205The GLUT header and library should go in the same directories. 206</p> 207<br> 208<br> 209 210 211<a name="part3"> 212</a><h1><a name="part3">3. Runtime / Rendering Problems</a></h1> 213 214<h2><a name="part3">3.1 Rendering is slow / why isn't my graphics hardware being used?</a></h2> 215<p> 216<a name="part3">Stand-alone Mesa (downloaded as MesaLib-x.y.z.tar.gz) doesn't have any 217support for hardware acceleration (with the exception of the 3DFX Voodoo 218driver). 219</a></p> 220<p> 221<a name="part3">What you really want is a DRI or NVIDIA (or another vendor's OpenGL) driver 222for your particular hardware. 223</a></p> 224<p> 225<a name="part3">You can run the <code>glxinfo</code> program to learn about your OpenGL 226library. 227Look for the GL_VENDOR and GL_RENDERER values. 228That will identify who's OpenGL library you're using and what sort of 229hardware it has detected. 230</a></p> 231<p> 232<a name="part3">If your DRI-based driver isn't working, go to the 233</a><a href="http://dri.sf.net/">DRI website</a> for trouble-shooting information. 234</p> 235 236 237<h2>3.2 I'm seeing errors in depth (Z) buffering. Why?</h2> 238<p> 239Make sure the ratio of the far to near clipping planes isn't too great. 240Look 241<a href="http://www.sgi.com/software/opengl/advanced97/notes/node18.html"> 242here</a> for details. 243</p> 244<p> 245Mesa uses a 16-bit depth buffer by default which is smaller and faster 246to clear than a 32-bit buffer but not as accurate. 247If you need a deeper you can modify the parameters to 248<code> glXChooseVisual</code> in your code. 249</p> 250 251 252<h2>3.3 Why Isn't depth buffering working at all?</h2> 253<p> 254Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG 255environment variable it will warn you about trying to enable depth testing 256when you don't have a depth buffer. 257</p> 258<p>Specifically, make sure <code>glutInitDisplayMode</code> is being called 259with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being 260called with a non-zero value for GLX_DEPTH_SIZE. 261</p> 262<p>This discussion applies to stencil buffers, accumulation buffers and 263alpha channels too. 264</p> 265 266 267<h2>3.4 Why does glGetString() always return NULL?</h2> 268<p> 269Be sure you have an active/current OpenGL rendering context before 270calling glGetString. 271</p> 272 273 274<h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels</h2> 275<p> 276If you're trying to draw a filled region by using GL_POINTS or GL_LINES 277and seeing holes or gaps it's because of a float-to-int rounding problem. 278But this is not a bug. 279See Appendix H of the OpenGL Programming Guide - "OpenGL Correctness Tips". 280Basically, applying a translation of (0.375, 0.375, 0.0) to your coordinates 281will fix the problem. 282</p> 283 284<br> 285<br> 286 287 288<a name="part4"> 289</a><h1><a name="part4">4. Developer Questions</a></h1> 290 291<h2><a name="part4">4.1 How can I contribute?</a></h2> 292<p> 293<a name="part4">First, join the Mesa3d-dev mailing list. That's where Mesa development 294is discussed. 295</a></p> 296<p> 297<a name="part4">The </a><a href="http://www.opengl.org/developers/documentation/specs.html"> 298OpenGL Specification</a> is the bible for OpenGL implemention work. 299You should read it. 300</p> 301<p>Most of the Mesa development work involves implementing new OpenGL 302extensions, writing hardware drivers (for the DRI), and code optimization. 303</p> 304 305<h2>4.2 How do I write a new device driver?</h2> 306<p> 307Unfortunately, writing a device driver isn't easy. 308It requires detailed understanding of OpenGL, the Mesa code, and your 309target hardware/operating system. 3103D graphics are not simple. 311</p> 312<p> 313The best way to get started is to use an existing driver as your starting 314point. 315For a software driver, the X11 and OSMesa drivers are good examples. 316For a hardware driver, the Radeon and R200 DRI drivers are good examples. 317</p> 318<p>The DRI website has more information about writing hardware drivers. 319The process isn't well document because the Mesa driver interface changes 320over time, and we seldome have spare time for writing documentation. 321That being said, many people have managed to figure out the process. 322</p> 323<p> 324Joining the appropriate mailing lists and asking questions (and searching 325the archives) is a good way to get information. 326</p> 327 328 329</body> 330</html> 331