forked from KolibriOS/kolibrios
406 lines
13 KiB
HTML
406 lines
13 KiB
HTML
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="content-type" content="text/html; charset=utf-8">
|
||
|
|
<title>Mesa FAQ</title>
|
||
|
|
<link rel="stylesheet" type="text/css" href="mesa.css">
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
|
||
|
|
<div class="header">
|
||
|
|
<h1>The Mesa 3D Graphics Library</h1>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<iframe src="contents.html"></iframe>
|
||
|
|
<div class="content">
|
||
|
|
|
||
|
|
<center>
|
||
|
|
<h1>Mesa Frequently Asked Questions</h1>
|
||
|
|
Last updated: 9 October 2012
|
||
|
|
</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>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
<h1 id="part1">1. High-level Questions and Answers</h1>
|
||
|
|
|
||
|
|
<h2>1.1 What is Mesa?</h2>
|
||
|
|
<p>
|
||
|
|
Mesa is an open-source implementation of the OpenGL specification.
|
||
|
|
OpenGL is a programming library for writing interactive 3D applications.
|
||
|
|
See the <a href="http://www.opengl.org/">OpenGL website</a> for more
|
||
|
|
information.
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
Mesa 9.x supports the OpenGL 3.1 specification.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>1.2 Does Mesa support/use graphics hardware?</h2>
|
||
|
|
<p>
|
||
|
|
Yes. Specifically, Mesa serves as the OpenGL core for the open-source DRI
|
||
|
|
drivers for X.org.
|
||
|
|
</p>
|
||
|
|
<ul>
|
||
|
|
<li>See the <a href="http://dri.freedesktop.org/">DRI website</a>
|
||
|
|
for more information.</li>
|
||
|
|
<li>See <a href="http://intellinuxgraphics.org">intellinuxgraphics.org</a>
|
||
|
|
for more information about Intel drivers.</li>
|
||
|
|
<li>See <a href="http://nouveau.freedesktop.org">nouveau.freedesktop.org</a>
|
||
|
|
for more information about Nouveau drivers.</li>
|
||
|
|
<li>See <a href="http://www.x.org/wiki/RadeonFeature">www.x.org/wiki/RadeonFeature</a>
|
||
|
|
for more information about Radeon drivers.</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<h2>1.3 What purpose does Mesa serve today?</h2>
|
||
|
|
<p>
|
||
|
|
Hardware-accelerated OpenGL implementations are available for most popular
|
||
|
|
operating systems today.
|
||
|
|
Still, Mesa serves at least these purposes:
|
||
|
|
</p>
|
||
|
|
<ul>
|
||
|
|
<li>Mesa is used as the core of the open-source X.org 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 What's the difference between "Stand-Alone" Mesa and the DRI drivers?</h2>
|
||
|
|
<p>
|
||
|
|
<em>Stand-alone Mesa</em> is the original incarnation of Mesa.
|
||
|
|
On systems running the X Window System it does all its rendering through
|
||
|
|
the Xlib API:
|
||
|
|
</p>
|
||
|
|
<ul>
|
||
|
|
<li>The GLX API is supported, but it's really just an emulation of the
|
||
|
|
real thing.
|
||
|
|
<li>The GLX wire protocol is not supported and there's no OpenGL extension
|
||
|
|
loaded by the X server.
|
||
|
|
<li>There is no hardware acceleration.
|
||
|
|
<li>The OpenGL library, libGL.so, contains everything (the programming API,
|
||
|
|
the GLX functions and all the rendering code).
|
||
|
|
</ul>
|
||
|
|
<p>
|
||
|
|
Alternately, Mesa acts as the core for a number of OpenGL hardware drivers
|
||
|
|
within the DRI (Direct Rendering Infrastructure):
|
||
|
|
<ul>
|
||
|
|
<li>The libGL.so library provides the GL and GLX API functions, a GLX
|
||
|
|
protocol encoder, and a device driver loader.
|
||
|
|
<li>The device driver modules (such as r200_dri.so) contain a built-in
|
||
|
|
copy of the core Mesa code.
|
||
|
|
<li>The X server loads the GLX module.
|
||
|
|
The GLX module decodes incoming GLX protocol and dispatches the commands
|
||
|
|
to a rendering module.
|
||
|
|
For the DRI, this module is basically a software Mesa renderer.
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
<h2>1.5 How do I upgrade my DRI installation to use a new Mesa release?</h2>
|
||
|
|
<p>
|
||
|
|
This wasn't easy in the past.
|
||
|
|
Now, the DRI drivers are included in the Mesa tree and can be compiled
|
||
|
|
separately from the X server.
|
||
|
|
Just follow the Mesa <a href="install.html">compilation instructions</a>.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>1.6 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://sourceforge.net/projects/ogl-es/">Vincent</a> is
|
||
|
|
an open-source implementation of OpenGL ES for mobile devices.
|
||
|
|
|
||
|
|
<p>
|
||
|
|
<a href="http://www.dsbox.com/minigl.html">miniGL</a>
|
||
|
|
is a subset of OpenGL for PalmOS devices.
|
||
|
|
|
||
|
|
<p>
|
||
|
|
<a href="http://bellard.org/TinyGL/">TinyGL</a>
|
||
|
|
is a subset of OpenGL.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>
|
||
|
|
<a href="http://sourceforge.net/projects/softgl/">SoftGL</a>
|
||
|
|
is an OpenGL subset for mobile devices.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>
|
||
|
|
<a href="http://chromium.sourceforge.net/">Chromium</a>
|
||
|
|
isn't a conventional OpenGL implementation (it's layered upon OpenGL),
|
||
|
|
but it does export the OpenGL API. It allows tiled rendering, sort-last
|
||
|
|
rendering, etc.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>
|
||
|
|
<a href="http://www.ticalc.org/archives/files/fileinfo/361/36173.html">ClosedGL</a>
|
||
|
|
is an OpenGL subset library for TI graphing calculators.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>
|
||
|
|
There may be other open OpenGL implementations, but Mesa is the most
|
||
|
|
popular and feature-complete.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h1 id="part2">2. Compilation and Installation Problems</h1>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>2.1 What's the easiest way to install Mesa?</h2>
|
||
|
|
<p>
|
||
|
|
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.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>2.2 I get undefined symbols such as bgnpolygon, v3f, etc...</h2>
|
||
|
|
<p>
|
||
|
|
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.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>2.3 Where is the GLUT library?</h2>
|
||
|
|
<p>
|
||
|
|
GLUT (OpenGL Utility Toolkit) is no longer in the separate MesaGLUT-x.y.z.tar.gz file.
|
||
|
|
If you don't already have GLUT installed, you should grab
|
||
|
|
<a href="http://freeglut.sourceforge.net/">freeglut</a>.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>2.4 Where is the GLw library?</h2>
|
||
|
|
<p>
|
||
|
|
GLw (OpenGL widget library) is now available from a separate <a href="http://cgit.freedesktop.org/mesa/glw/">git repository</a>. Unless you're using very old Xt/Motif applications with OpenGL, you shouldn't need it.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>2.5 What's the proper place for the libraries and headers?</h2>
|
||
|
|
<p>
|
||
|
|
On Linux-based systems you'll want to follow the
|
||
|
|
<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></ul>
|
||
|
|
<p>
|
||
|
|
When configuring Mesa, there are three autoconf options that affect the install
|
||
|
|
location that you should take care with: <code>--prefix</code>,
|
||
|
|
<code>--libdir</code>, and <code>--with-dri-driverdir</code>. To install Mesa
|
||
|
|
into the system location where it will be available for all programs to use, set
|
||
|
|
<code>--prefix=/usr</code>. Set <code>--libdir</code> to where your Linux
|
||
|
|
distribution installs system libraries, usually either <code>/usr/lib</code> or
|
||
|
|
<code>/usr/lib64</code>. Set <code>--with-dri-driverdir</code> to the directory
|
||
|
|
where your Linux distribution installs DRI drivers. To find your system's DRI
|
||
|
|
driver directory, try executing <code>find /usr -type d -name dri</code>. For
|
||
|
|
example, if the <code>find</code> command listed <code>/usr/lib64/dri</code>,
|
||
|
|
then set <code>--with-dri-driverdir=/usr/lib64/dri</code>.
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
After determining the correct values for the install location, configure Mesa
|
||
|
|
with <code>./configure --prefix=/usr --libdir=xxx --with-dri-driverdir=xxx</code>
|
||
|
|
and then install with <code>sudo make install</code>.
|
||
|
|
</p>
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h1 id="part3">3. Runtime / Rendering Problems</h1>
|
||
|
|
|
||
|
|
<h2>3.1 Rendering is slow / why isn't my graphics hardware being used?</h2>
|
||
|
|
<p>
|
||
|
|
If Mesa can't use its hardware accelerated drivers it falls back on one of its software renderers.
|
||
|
|
(eg. classic swrast, softpipe or llvmpipe)
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
You can run the <code>glxinfo</code> program to learn about your OpenGL
|
||
|
|
library.
|
||
|
|
Look for the <code>OpenGL vendor</code> and <code>OpenGL renderer</code> values.
|
||
|
|
That will identify who's OpenGL library with which driver you're using and what sort of
|
||
|
|
hardware it has detected.
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
If you're using a hardware accelerated driver you want <code>direct rendering: Yes</code>.
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
If your DRI-based driver isn't working, go to the
|
||
|
|
<a href="http://dri.freedesktop.org/">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.opengl.org/resources/faq/technical/depthbuffer.htm#0040">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>
|
||
|
|
|
||
|
|
<h2>3.6 How can I change the maximum framebuffer size in Mesa's
|
||
|
|
<tt>swrast</tt> backend?</h2>
|
||
|
|
<p>
|
||
|
|
These can be overridden by using the <tt>--with-max-width</tt> and
|
||
|
|
<tt>--with-max-height</tt> options. The two need not be equal.
|
||
|
|
</p><p>
|
||
|
|
Do note that Mesa uses these values to size some internal buffers,
|
||
|
|
so increasing these sizes will cause Mesa to require additional
|
||
|
|
memory. Furthermore, increasing these limits beyond <tt>4096</tt>
|
||
|
|
may introduce rasterization artifacts; see the leading comments in
|
||
|
|
<tt>src/mesa/swrast/s_tritemp.h</tt>.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<h1 id="part4">4. Developer Questions</h1>
|
||
|
|
|
||
|
|
<h2>4.1 How can I contribute?</h2>
|
||
|
|
<p>
|
||
|
|
First, join the <a href="lists.html">mesa-dev mailing list</a>.
|
||
|
|
That's where Mesa development is discussed.
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
The <a href="http://www.opengl.org/documentation">
|
||
|
|
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 classic hardware driver, the i965 driver is a good example.
|
||
|
|
For a Gallium3D hardware driver, the r300g, r600g and the i915g 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>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa?</h2>
|
||
|
|
<p>
|
||
|
|
The <a href="http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt">specification for the extension</a>
|
||
|
|
indicates that there are intellectual property (IP) and/or patent issues
|
||
|
|
to be dealt with.
|
||
|
|
</p>
|
||
|
|
<p>We've been unsucessful in getting a response from S3 (or whoever owns
|
||
|
|
the IP nowadays) to indicate whether or not an open source project can
|
||
|
|
implement the extension (specifically the compression/decompression
|
||
|
|
algorithms).
|
||
|
|
</p>
|
||
|
|
<p>
|
||
|
|
In the mean time, a 3rd party <a href="http://dri.freedesktop.org/wiki/S3TC">
|
||
|
|
plug-in library</a> is available.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|