Mesa 4.0.4 (stable version) Copyright (C) 1995-2002 Brian Paul www.mesa3d.org Disclaimer ========== Mesa is a 3-D graphics library with an API which is very similar to that of OpenGL*. To the extent that Mesa utilizes the OpenGL command syntax or state machine, it is being used with authorization from Silicon Graphics, Inc. However, the author makes no claim that Mesa is in any way a compatible replacement for OpenGL or associated with Silicon Graphics, Inc. Those who want a licensed implementation of OpenGL should contact a licensed vendor. While Mesa is not a licensed OpenGL implementation, it is currently being tested with the OpenGL conformance tests. For the current conformance status see the CONFORM file included in the Mesa distribution. * OpenGL(R) is a registered trademark of Silicon Graphics, Inc. Original Author =============== Brian Paul See www.mesa3d.org for current email address. Many people have contributed to Mesa. A partial list is below. Copyright Information ===================== See the docs/COPYRIGHT file. Introduction ============ While Mesa uses the OpenGL API and mimics its semantics, it is important to understand that Mesa is not a real implementation of OpenGL since it is not licensed. That said, Mesa is still a viable alternative to OpenGL. Most OpenGL applications should run with Mesa without code changes. The first six years of Mesa development were done during my spare time from August 1993 to August 1999. Now, much of the Mesa development work is done during my working hours with Precision Insight, Inc. The core library was originally written on an Amiga using the DCC compiler. Later, development was moved to an SGI workstation. Current development is done on PC/Linux systems. Mesa works on most Unix workstations with ANSI C and X11. There are also drivers for Amiga, Microsoft Windows, Macintosh, MS DOS, NeXT, BeOS and other systems. Unix/X11 is still the best-supported platform. Since the OpenGL API is used, OpenGL documentation can serve as the documentation for Mesa's core functions. Visit http://www.opengl.org/ for extensive OpenGL information. The primary design goal of this library has been correctness. Performance has been a secondary (but still very important!) priority. At this point, most common rendering operations have been optimized a great deal. However, if you find an obscure code path that isn't as fast as you think it could be (like glDrawPixels with lookup tables and a crazy blend mode) send a note to the author; it might not be hard to improve the path. Better yet, try optimizing that path yourself and send a patch. Getting the software ==================== Mesa can be downloaded from http://sourceforge.net/project/filelist.php?group_id=3 or from http://www.mesa3d.org/ Since version 2.3, Mesa is distributed in two pieces: main library code and demos. If you're upgrading from a previous version of Mesa or you're not interested in the demos you can just download the core Mesa archive file. Mesa is available in at least three archive formats: 1. GNU zip/tar Download MesaLib-4.0.4.tar.gz and optionally MesaDemos-4.0.4.tar.gz Unpack with: gzcat MesaLib-4.0.4.tar.gz | tar xf - gzcat MesaDemos-4.0.4.tar.gz | tar xf - or gunzip MesaLib-4.0.4.tar.gz ; tar xf MesaLib-4.0.4.tar gunzip MesaDemos-4.0.4.tar.gz ; tar xf MesaLib-4.0.4.tar or tar zxf MesaLib-4.0.4.tar.gz tar zxf MesaDemos-4.0.4.tar.gz If you don't have gzcat try zcat instead. 2. Unix compressed/tar Download MesaLib-4.0.4.tar.Z and optionally MesaDemos-4.0.4.tar.Z Unpack with: zcat MesaLib-4.0.4.tar.Z | tar xf - zcat MesaDemos-4.0.4.tar.Z | tar xf - 3. ZIP format Download MesaLib-4.0.4.zip and optionally MesaDemos-4.0.4.zip Unpack with: unzip MesaLib-4.0.4.zip unzip MesaDemos-4.0.4.zip Note, there may be other package formats on the Mesa ftp/web site. After unpacking you'll have these files (and more): docs/README - this file docs/README.* - detailed information for specific OS/hardware systems docs/COPYRIGHT - copyright /license info docs/VERSIONS - version history docs/RELNOTES - release notes for the new version docs/CONFORM - results of conformance testing Makefile.X11 - "old" top-level Makefile for X11-based systems Make-config - "old" system configurations used by the Makefiles bin/mklib.* - shell scripts for making shared libraries for some systems include/ - client include files lib/ - client libraries, created during installation src/ - source code for core library src-glu/ - source code for utility library util/ - handly utility functions widgets-mesa/ - Mesa widgets for Xt/Motif widgets-sgi/ - SGI OpenGL widgets for Xt/Motif and if you downloaded and unpacked the demos: src-glut/ - source code for GLUT toolkit demos/ - GLUT demos xdemos/ - X11 and SVGA demo programs samples/ - sample OpenGL programs from SGI book/ - example programs from the OpenGL Programming Guide, converted to GLUT by Mark Kilgard, from GLUT distribution. images/ - image files 3Dfx/ - 3Dfx demos and tests mtdemos/ - multi-threading demos GLUT ==== Mesa 2.5 and later includes Mark Kilgard's GLUT library (GL Utility Toolkit). GLUT is built automatically on systems which support it. The GLUT tests, demos, examples, etc are not included, just the main library. To obtain the latest complete release of GLUT please visit http://www.opengl.org/developers/documentation/glut/index.html Compiling and Installation ========================== See the INSTALL file for instructions. Using the Library ================= Performance tips for software rendering: 1. Turn off smooth shading when you don't need it (glShadeModel) 2. Turn off depth buffering when you don't need it. 3. Turn off dithering when not needed. 4. Use double buffering as it's often faster than single buffering 5. Compile in the X Shared Memory extension option if it's supported on your system by adding -DSHM to CFLAGS and -lXext to XLIBS for your system in the Make-config file. 6. Recompile Mesa with more optimization if possible. 7. Try to maximize the amount of drawing done between glBegin/glEnd pairs. 8. Use the MESA_BACK_BUFFER variable to find best performance in double buffered mode. (X users only) 9. Optimized polygon rasterizers are employed when: rendering into back buffer which is an XImage RGB mode, not grayscale, not monochrome depth buffering is GL_LESS, or disabled flat or smooth shading dithered or non-dithered no other rasterization operations enabled (blending, stencil, etc) 10. Optimized line drawing is employed when: rendering into back buffer which is an XImage RGB mode, not grayscale, not monochrome depth buffering is GL_LESS or disabled flat shading dithered or non-dithered no other rasterization operations enabled (blending, stencil, etc) 11. Textured polygons are fastest when: using a 3-component (RGB), 2-D texture minification and magnification filters are GL_NEAREST texture coordinate wrap modes for S and T are GL_REPEAT GL_DECAL environment mode glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST ) depth buffering is GL_LESS or disabled 12. Lighting is fastest when: Two-sided lighting is disabled GL_LIGHT_MODEL_LOCAL_VIEWER is false GL_COLOR_MATERIAL is disabled No spot lights are used (all GL_SPOT_CUTOFFs are 180.0) No local lights are used (all position W's are 0.0) All material and light coefficients are >= zero 13. XFree86 users: if you want to use 24-bit color try starting your X server in 32-bit per pixel mode for better performance. That is, start your X server with startx -- -bpp 32 instead of startx -- -bpp 24 14. Try disabling dithering with the MESA_NO_DITHER environment variable. If this env var is defined Mesa will disable dithering and the command glEnable(GL_DITHER) will be ignored. Debugging: Normally Mesa records but does not notify the user of errors. It is up to the application to call glGetError to check for errors. Mesa supports an environment variable, MESA_DEBUG, to help with debugging. If MESA_DEBUG is defined, a message will be printed to stdout whenever an error occurs. More extensive error checking is done when Mesa is compiled with the DEBUG symbol defined. You'll have to edit the Make-config file and add -DDEBUG to the CFLAGS line for your system configuration. You may also want to replace any optimization flags with the -g flag so you can use your debugger. After you've edited Make-config type 'make clean' before recompiling. In your debugger you can set a breakpoint in gl_error() to trap Mesa errors. There is a display list printing/debugging facility. See the end of src/dlist.c for details. Fortran bindings: Fortan bindings are no longer included with Mesa. William F. Mitchell (william.mitchell@nist.gov) has developed a new set of Mesa/OpenGL and GLUT bindings for Fortran. See http://math.nist.gov/f90gl for more information. Off-screen rendering: Mesa 1.2.4 introduced off-screen rendering, a facility for generating 3-D imagery without having to open a window on your display. Mesa's simple off-screen rendering interface is completely operating system and window system independent so programs which use off-screen rendering should be very portable. This new feature effectively enables you to use Mesa as an off-line, batch-oriented renderer. The "OSMesa" API provides 3 functions for making off-screen renderings: OSMesaCreateContext(), OSMesaMakeCurrent(), and OSMesaDestroyContext(). See the Mesa/include/GL/osmesa.h header for more information. See the demos/osdemo.c file for an example program. There is no facility for writing images to files. If you want to generate large images (larger than 1280x1024) you'll have to edit the src/config.h file to change MAX_WIDTH and MAX_HEIGHT then recompile Mesa. Image size should only be limited by available memory. Deep color channels: For some applications 8-bit color channels don't have sufficient accuracy (film and IBR, for example). If you're in this situation you'll be happy to know that Mesa supports 16-bit and 32-bit color channels through the OSMesa interface. When using 16-bit channels, channels are GLushorts and pixels occupy 8 bytes. When using 32-bit channels, channels are GLfloats and pixels occupy 16 bytes. To build Mesa/OSMesa with 16-bit color channels: cd Mesa-4.x/src make -f Makefile.X11 clean make -f Makefile.OSMesa16 linux-osmesa16 For 32-bit channels: cd Mesa-4.x/src make -f Makefile.X11 clean make -f Makefile.OSMesa16 linux-osmesa32 If you're not using Linux, you can easily edit Make-config and add an appropriate configuration. The Mesa/tests/osdemo16.c file (available via CVS) demonstrates how to use this feature. BE WARNED: 16 and 32-bit channel support has not been exhaustively tested and there may be some bugs. However, a number of people have been using this feature successfully so it can't be too broken. Profiling (may no longer work in Mesa 3.1 or later, sorry): Mesa 1.2.6 introduced a simple profiling facility. It counts and measures the time spent in a number of important rendering operations and prints the information in a report before your program exits. By default, profiling is disabled. To enable it, add -DPROFILE to the appropriate CFLAGS entry in the Make-config file, then recompile Mesa. In general, you should only enable profiling during program development to gain insight into Mesa's performance. Mesa runs a bit slower when profiling is enabled because it requires frequent polling of the system clock. The profiling report will be printed when glXDestroyContext is called _if_ the MESA_PROFILE environment variable is set. You must be sure glXDestroyContext is called before exiting to get the profile report. The report will be printed to stdout and includes: glBegin/glEnd - number of glBegin/glEnd pairs called, total time, and rate in pairs/second. vertexes transformed - number of vertices transformed, lit, clip- tested, fogged, and mapped to window coordinates, total time, and rate in vertexes/second. points rasterized - number of points drawn, time, and rate. lines rasterized - number of lines drawn, time, and rate. polygons rasterized - number of polygons drawn, time and rate. overhead - time between glBegin/glEnd not accounted for by vertexes, points, lines, and polygons. This is time spent executing glVertex, glNormal, glColor, etc, clipping, primitive assembly, and user code between glBegin/glEnd. glClear - number of glClears executed, total time and clears/second. SwapBuffers - number of swaps executed, total time and swaps/second. Note that the real point, line, and polygon rates should be computed by adding in the vertex transformation and overhead time factors. Extensions: Mesa supports quite a few OpenGL extensions. The set of available extensions depends on the device driver you're using. Run the glinfo program to learn which extensions are available on your computer. There are a few Mesa-specific extensions: GL_MESA_window_pos This extension adds the glWindowPos*MESA() functions. These functions are convenient alternatives to glRasterPos*() because they set the current raster position to a specific window coordinate, bypassing the usual modelview, projection and viewport transformations. This is especially useful for setting the position for glDrawPixels() or glBitmap() to a specific window coordinate. See the docs/MESA_window_pos.spec file for details. GL_MESA_resize_buffers This extension adds the glResizeBuffersMESA() function. When this function is called, Mesa checks if the color buffer (window) has been resized. If it has, Mesa reallocates the ancillary (depth, stencil, accum) buffers. Normally, Mesa checks for window size changes whenever glViewport() is called. In some applications it may not be appropriate to call glViewport() when the window is resized. Such applications should call glResizeBuffersMESA() instead so the ancillary buffers are correctly updated. See the docs/MESA_resize_buffers.spec file for more details. This extension is new in version 2.2. Runtime Configuration File: See the CONFIG file for information on how to setup a Mesa runtime config file. Version 2.x features: Version 2.x of Mesa implements the OpenGL 1.1 API with the following new features. Texture mapping: glAreTexturesResident glBindTexture glCopyTexImage1D glCopyTexImage2D glCopyTexSubImage1D glCopyTexSubImage2D glDeleteTextures glGenTextures glIsTexture glPrioritizeTextures glTexSubImage1D glTexSubImage2D Vertex Arrays: glArrayElement glColorPointer glDrawElements glEdgeFlagPointer glIndexPointer glInterleavedArrays glNormalPointer glTexCoordPointer glVertexPointer Client state management: glDisableClientState glEnableClientState glPopClientAttrib glPushClientAttrib Misc: glGetPointer glIndexub glIndexubv glPolygonOffset Version 3.x features: Version 3.x of Mesa implements the OpenGL 1.2 API with the following new features: BGR, BGRA and packed pixel formats New texture border clamp mode glDrawRangeElements() standard 3-D texturing advanced MIPMAP control separate specular color interpolation Version 4.x features: Version 4.x of Mesa implements the OpenGL 1.3 API with the following extensions incorporated as standard features: GL_ARB_multisample GL_ARB_multitexture GL_ARB_texture_border_clamp GL_ARB_texture_compression GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_texture_env_combine GL_ARB_texture_env_dot3 GL_ARB_transpose_matrix The functions defined by these extensions are now available without the "ARB" suffix. For example, glLoadTransposeMatrixf() is now a standard API function. Summary of environment variables: MESA_DEBUG - if defined, error messages are printed to stderr MESA_NO_DITHER - disable dithering, overriding glEnable(GL_DITHER) MESA_RGB_VISUAL - specifies the X visual and depth for RGB mode (X only) MESA_CI_VISUAL - specifies the X visual and depth for CI mode (X only) MESA_BACK_BUFFER - specifies how to implement the back color buffer (X only) MESA_PRIVATE_CMAP - force aux/tk libraries to use private colormaps (X only) MESA_GAMMA - gamma correction coefficients (X only) MESA_PROFILE - enable reporting of performance measurements MESA_XSYNC - enable synchronous X behavior (for X debugging only) Mailing Lists ============= Visit the Mesa web site at http://www.mesa3d.org to join the mailing lists. There is a user's list, developer's list and announcement list. Reporting Bugs ============== If you think you've found a bug in Mesa: 1. Check if there's a new version of Mesa to download. 2. Check if the bug has already been reported in the Mesa bug database at http://www.mesa3d.org 3. If you've found a new bug, submit it to the bug database. Provide as much information as possible! Check back on the bug report from time to time to monitor its status. 4. Please provide small test programs when possible. Making Contributions ==================== Many people have contributed to Mesa. I really appreciate the help! See the Mesa web site for a list of past and current contributors. If you want to help with Mesa, first join the Mesa developer's mailing list. Then post a message explaining what you might like to help with. The Mesa web page has a list of a few work items which you may consider. Anyone is welcome to contribute code to the Mesa project, provided you agree to the copyright terms of the relevant code. See the COPYRIGHT file. If you're contribution code to the Mesa library itself: 1. Try to write clean code (uniform indentation, comments, meaningful identifiers, etc). It must be readable and maintainable! 2. Test your code. On several occations I've incorporated code from users which later turned out to have bugs. Now, I'm pretty hesitant to use code which doesn't look good. Why is it the library called Mesa? ================================== Why not? More obvious names were considered but had to be rejected: FreeGL (too similar to the trademarked name OpenGL), Free3D (too similar to DEC's Open3D). Also, I'm tired of acronyms. -------------------------------------------------------------------------- $Id: README,v 3.32.2.5 2002/09/03 17:50:20 brianp Exp $