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| author | Brian Paul <brian.paul@tungstengraphics.com> | 2003-03-08 17:38:57 +0000 |
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| committer | Brian Paul <brian.paul@tungstengraphics.com> | 2003-03-08 17:38:57 +0000 |
| commit | 0b27aceae2464db3dd149cf4fd667e353a655c5e (patch) | |
| tree | a8df88dd0893e04a6fe4f125ddd361a1bde9d7ae /docs/faq.html | |
| parent | dc32636cfd38916ad7b2150e10765026dbb64ce5 (diff) | |
Documentation/website overhaul. The website content and doc/ directory
are now merged and are one and the same.
Diffstat (limited to 'docs/faq.html')
| -rw-r--r-- | docs/faq.html | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/docs/faq.html b/docs/faq.html new file mode 100644 index 0000000000..448def5274 --- /dev/null +++ b/docs/faq.html @@ -0,0 +1,330 @@ +<html> + +<head><title>Mesa FAQ</title></head> + +<BODY text="#000000" bgcolor="#55bbff" link="#111188"> + + +<center> +<h1>Mesa Frequently Asked Questions</h1> +Last updated: 7 March 2003 +</center> + +<br> +<br> +<h2>Index</h2> +<a href="#part1">1. High-level Questions and Answers</a> +<br> +<a href="#part2">2. Compilation and Installation Problems</a> +<br> +<a href="#part3">3. Runtime / Rendering Problems</a> +<br> +<a href="#part4">4. Developer Questions</a> +<br> +<br> +<br> + + + +<a name="part1"> +</a><h1><a name="part1">1. High-level Questions and Answers</a></h1> + +<h2><a name="part1">1.1 What is Mesa?</a></h2> +<p> +<a name="part1">Mesa is an open-source implementation of the OpenGL specification. +OpenGL is a high-level programming library for interactive 3D graphics. +See the </a><a href="http://www.opengl.org/">OpenGL website</a> for more +information. +</p> +<p> +Mesa 5.0.x supports the OpenGL 1.4 specification. +</p> + + +<h2>1.2 Does Mesa support/use graphics hardware?</h2> +<p> +Yes. Specifically, Mesa serves as the OpenGL core for the XFree86/DRI +OpenGL drivers. See the <a href="http://dri.sf.net/">DRI website</a> for +more information. +</p> +<p> +There have been other hardware drivers for Mesa over the years (such as +the 3Dfx Glide/Voodoo driver, an old S3 driver, etc) but the DRI drivers +are the modern ones. +</p> + +<h2>1.3 What purpose does (software) Mesa serve today?</h2> +<p> +Commercial, hardware-accelerated OpenGL implementations are available for +many operating systems today. +Still, Mesa serves at least these purposes: +</p> +<ul> +<li>Mesa is used as the core of the XFree86/DRI hardware drivers. +</li><li>Mesa is quite portable and allows OpenGL to be used on systems that have + no other OpenGL solution. +</li><li>Software rendering with Mesa serves as a reference for validating the + hardware drivers. +</li><li>A software implementation of OpenGL is useful for experimentation, such + as testing new rendering techniques. +</li><li>Mesa can render images with deep color channels: 16-bit integer and 32-bit + floating point color channels are supported. + This capability is only now appearing in hardware. +</li><li>Mesa's internal limits (max lights, clip planes, texture size, etc) can be + changed for special needs (hardware limits are hard to overcome). +</li></ul> + +<h2>1.4 How do I upgrade my DRI installation to use a new Mesa release?</h2> +<p> +You don't! The Mesa source code lives inside the XFree86/DRI source tree +and gets compiled into the individual DRI driver modules. +If you try to install Mesa over an XFree86/DRI installation, you'll lose +hardware rendering (because Mesa's libGL.so is different than the XFree86 +libGL.so). +</p> +<p> +The DRI developers will incorporate the latest release of Mesa into the +DRI drivers when the time is right. +</p> + +<h2>1.5 Are there other open-source implementations of OpenGL?</h2> +<p> +Yes, SGI's <a href="http://oss.sgi.com/projects/ogl-sample/index.html"> +OpenGL Sample Implemenation (SI)</a> is available. +The SI was written during the time that OpenGL was originally designed. +Unfortunately, development of the SI has stagnated. +Mesa is much more up to date with modern features and extensions. +</p> +<p> +<a href="http://www.dsbox.com/minigl.html">miniGL</a> is a subset of OpenGL +for PalmOS devices. + +<a href="http://fabrice.bellard.free.fr/TinyGL/">TinyGL</a> is another +subset of OpenGL. +</p> +<p> +There may be others but Mesa is the most popular and feature-complete. +</p> + +<br> +<br> + + +<a name="part2"> +</a><h1><a name="part2">2. Compilation and Installation Problems</a></h1> + + +<h2><a name="part2">2.1 What's the easiest way to install Mesa?</a></h2> +<p> +<a name="part2">If you're using a Linux-based system, your distro CD most likely already +has Mesa packages (like RPM or DEB) which you can easily install. +</a></p> + + +<h2><a name="part2">2.2 Running <code>configure; make</code> Doesn't Work</a></h2> +<p> +<a name="part2">Unfortunately, the GNU autoconf/automake/libtool system doesn't seem to work +too well on non GNU/Linux systems, even after installing gmake, gcc, etc. +For that reason, Mesa's <b>old-style</b> makefile system is still included. +The old-style system uses good old traditional Makefiles. Try the following: +</a></p><pre><a name="part2"> cd Mesa-x.y.z + cp Makefile.X11 Makefile + make +</a></pre> +<a name="part2">You'll see a list of system configurations from which to choose. +For example: +</a><pre><a name="part2"> make linux-x86 +</a></pre> +<p> +<a name="part2">If you're experienced with GNU autoconf/automake/libtool and think you can help +with maintence, contact the Mesa developers. +FYI, the Mesa developers generally don't use the autoconf/automake system. +We're especially annoyed with the fact that a +5000-line script (libtool) +is needed to make shared libraries (ugh). +</a></p> + +<h2><a name="part2">2.3 Mesa still doesn't compile</a></h2> +<p> +<a name="part2">If the old-style Makefile system doesn't work either, make sure you have +the most recent version of Mesa. +Otherwise, file a bug report or post to the Mesa3d-users mailing list. +Give as much info as possible when describing your problem. +</a></p> + + +<h2><a name="part2">2.4 I get undefined symbols such as bgnpolygon, v3f, etc...</a></h2> +<p> +<a name="part2">You're application is written in IRIS GL, not OpenGL. +IRIS GL was the predecessor to OpenGL and is a different thing (almost) +entirely. +Mesa's not the solution. +</a></p> + + +<h2><a name="part2">2.5 Where is the GLUT library?</a></h2> +<p> +<a name="part2">GLUT (OpenGL Utility Toolkit) is in the separate MesaDemos-x.y.z.tar.gz file. +If you don't already have GLUT installed, you should grab the MesaDemos +package and unpack it before compiling Mesa. +</a></p> + + + +<h2><a name="part2">2.6 What's the proper place for the libraries and headers?</a></h2> +<p> +<a name="part2">On Linux-based systems you'll want to follow the +</a><a href="http://oss.sgi.com/projects/ogl-sample/ABI/index.html">Linux ABI</a> +standard. +Basically you'll want the following: +</p> +<ul> +<li>/usr/include/GL/gl.h - the main OpenGL header +</li><li>/usr/include/GL/glu.h - the OpenGL GLU (utility) header +</li><li>/usr/include/GL/glx.h - the OpenGL GLX header +</li><li>/usr/include/GL/glext.h - the OpenGL extensions header +</li><li>/usr/include/GL/glxext.h - the OpenGL GLX extensions header +</li><li>/usr/include/GL/osmesa.h - the Mesa off-screen rendering header +</li><li>/usr/lib/libGL.so - a symlink to libGL.so.1 +</li><li>/usr/lib/libGL.so.1 - a symlink to libGL.so.1.xyz +</li><li>/usr/lib/libGL.so.xyz - the actual OpenGL/Mesa library. xyz denotes the +Mesa version number. +</li><li>/usr/lib/libGLU.so - a symlink to libGLU.so.1 +</li><li>/usr/lib/libGLU.so.1 - a symlink to libGLU.so.1.3.xyz +</li><li>/usr/lib/libGLU.so.xyz - the OpenGL Utility library. xyz denotes the Mesa +version number. +</li></ul> +<p> +After installing XFree86 and the DRI drivers, some of these files +may be symlinks into the /usr/X11R6/ tree. +</p> +<p> +The old-style Makefile system doesn't install the Mesa libraries; it's +up to you to copy them (and the headers) to the right place. +</p> +<p> +The GLUT header and library should go in the same directories. +</p> +<br> +<br> + + +<a name="part3"> +</a><h1><a name="part3">3. Runtime / Rendering Problems</a></h1> + +<h2><a name="part3">3.1 Rendering is slow / why isn't my graphics hardware being used?</a></h2> +<p> +<a name="part3">Stand-alone Mesa (downloaded as MesaLib-x.y.z.tar.gz) doesn't have any +support for hardware acceleration (with the exception of the 3DFX Voodoo +driver). +</a></p> +<p> +<a name="part3">What you really want is a DRI or NVIDIA (or another vendor's OpenGL) driver +for your particular hardware. +</a></p> +<p> +<a name="part3">You can run the <code>glxinfo</code> program to learn about your OpenGL +library. +Look for the GL_VENDOR and GL_RENDERER values. +That will identify who's OpenGL library you're using and what sort of +hardware it has detected. +</a></p> +<p> +<a name="part3">If your DRI-based driver isn't working, go to the +</a><a href="http://dri.sf.net/">DRI website</a> for trouble-shooting information. +</p> + + +<h2>3.2 I'm seeing errors in depth (Z) buffering. Why?</h2> +<p> +Make sure the ratio of the far to near clipping planes isn't too great. +Look +<a href="http://www.sgi.com/software/opengl/advanced97/notes/node18.html"> +here</a> for details. +</p> +<p> +Mesa uses a 16-bit depth buffer by default which is smaller and faster +to clear than a 32-bit buffer but not as accurate. +If you need a deeper you can modify the parameters to +<code> glXChooseVisual</code> in your code. +</p> + + +<h2>3.3 Why Isn't depth buffering working at all?</h2> +<p> +Be sure you're requesting a depth buffered-visual. If you set the MESA_DEBUG +environment variable it will warn you about trying to enable depth testing +when you don't have a depth buffer. +</p> +<p>Specifically, make sure <code>glutInitDisplayMode</code> is being called +with <code>GLUT_DEPTH</code> or <code>glXChooseVisual</code> is being +called with a non-zero value for GLX_DEPTH_SIZE. +</p> +<p>This discussion applies to stencil buffers, accumulation buffers and +alpha channels too. +</p> + + +<h2>3.4 Why does glGetString() always return NULL?</h2> +<p> +Be sure you have an active/current OpenGL rendering context before +calling glGetString. +</p> + + +<h2>3.5 GL_POINTS and GL_LINES don't touch the right pixels</h2> +<p> +If you're trying to draw a filled region by using GL_POINTS or GL_LINES +and seeing holes or gaps it's because of a float-to-int rounding problem. +But this is not a bug. +See Appendix H of the OpenGL Programming Guide - "OpenGL Correctness Tips". +Basically, applying a translation of (0.375, 0.375, 0.0) to your coordinates +will fix the problem. +</p> + +<br> +<br> + + +<a name="part4"> +</a><h1><a name="part4">4. Developer Questions</a></h1> + +<h2><a name="part4">4.1 How can I contribute?</a></h2> +<p> +<a name="part4">First, join the Mesa3d-dev mailing list. That's where Mesa development +is discussed. +</a></p> +<p> +<a name="part4">The </a><a href="http://www.opengl.org/developers/documentation/specs.html"> +OpenGL Specification</a> is the bible for OpenGL implemention work. +You should read it. +</p> +<p>Most of the Mesa development work involves implementing new OpenGL +extensions, writing hardware drivers (for the DRI), and code optimization. +</p> + +<h2>4.2 How do I write a new device driver?</h2> +<p> +Unfortunately, writing a device driver isn't easy. +It requires detailed understanding of OpenGL, the Mesa code, and your +target hardware/operating system. +3D graphics are not simple. +</p> +<p> +The best way to get started is to use an existing driver as your starting +point. +For a software driver, the X11 and OSMesa drivers are good examples. +For a hardware driver, the Radeon and R200 DRI drivers are good examples. +</p> +<p>The DRI website has more information about writing hardware drivers. +The process isn't well document because the Mesa driver interface changes +over time, and we seldome have spare time for writing documentation. +That being said, many people have managed to figure out the process. +</p> +<p> +Joining the appropriate mailing lists and asking questions (and searching +the archives) is a good way to get information. +</p> + + +</body> +</html> |