Mesa is an open-source implementation of the OpenGL specification. OpenGL is a programming library for writing interactive 3D applications. See the OpenGL website for more information.
Mesa 5.x supports the OpenGL 1.4 specification.
Yes. Specifically, Mesa serves as the OpenGL core for the open-source XFree86/DRI OpenGL drivers. See the DRI website for more information.
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.
Hardware-accelerated OpenGL implementations are available for most popular operating systems today. Still, Mesa serves at least these purposes:
You don't! A copy of 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 stand-alone Mesa's libGL.so is different than the XFree86 libGL.so).
The DRI developers will incorporate the latest release of Mesa into the DRI drivers when the time is right.
To upgrade, either look for a new release of XFree86 or visit the DRI website to see if there's newer drivers.
Yes, SGI's OpenGL Sample Implemenation (SI) 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.
miniGL is a subset of OpenGL for PalmOS devices.
TinyGL is a subset of OpenGL.
SoftGL is an OpenGL subset for mobile devices.
Chromium 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.
There may be other open OpenGL implementations, but Mesa is the most popular and feature-complete.
configure; make Doesn't Workcd Mesa-x.y.z cp Makefile.X11 Makefile makeYou'll see a list of system configurations from which to choose. For example:
make linux-x86
On Linux-based systems you'll want to follow the Linux ABI standard. Basically you'll want the following:
After installing XFree86 and the DRI drivers, some of these files may be symlinks into the /usr/X11R6/ tree.
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.
The GLUT header and library should go in the same directories.
If your DRI-based driver isn't working, go to the DRI website for trouble-shooting information.
Make sure the ratio of the far to near clipping planes isn't too great. Look here for details.
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
glXChooseVisual in your code.
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.
Specifically, make sure glutInitDisplayMode is being called
with GLUT_DEPTH or glXChooseVisual is being
called with a non-zero value for GLX_DEPTH_SIZE.
This discussion applies to stencil buffers, accumulation buffers and alpha channels too.
Be sure you have an active/current OpenGL rendering context before calling glGetString.
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.
First, join the Mesa3d-dev mailing list. That's where Mesa development is discussed.
The OpenGL Specification is the bible for OpenGL implemention work. You should read it.
Most of the Mesa development work involves implementing new OpenGL extensions, writing hardware drivers (for the DRI), and code optimization.
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.
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.
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.
Joining the appropriate mailing lists and asking questions (and searching the archives) is a good way to get information.