     ______   ___    ___
    /\  _  \ /\_ \  /\_ \
    \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___ 
     \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
      \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
       \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
        \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
                                       /\____/
                                       \_/__/


                 Unix-specific information.

         See readme.txt for a more general overview.

   Also see docs/build/linux.txt for Linux-specific information.

Unix notes

On Linux you have two different system drivers -- one for running using X, and one for running without X. This file describes the X version, which should be portable to any Unix variant. For information about the Linux-specific console routines, see docs/build/linux.txt.

Only the X version is installed by default.

Required software

Chances are that you already have all the necessary development tools, at least for compiling and installing the library. You will need CMake 2.6 or above. Most distributions should include it now, otherwise you will need to install it yourself.

Installing Allegro

Please follow the generic instructions in docs/build/cmake.txt.

Shared files

Installing Allegro will copy the library and header files plus other support files. These are:

allegro-config: Script that outputs the correct compiler and linker flags for your system in order to compile Allegro. This is copied into a `.../bin' path.
pkg-config files. These are alternatives to the allegro-config script.

On the other hand, there are files which you, as system administrator, are required to installed manually. These are:

language.dat: Contains translations for text strings used by Allegro. If this file is not available, Allegro runtime messages will only speak English. Recommended location is `/usr[/local]/share/allegro'.
allegro.info: Allegro documentation in Info format, viewable with GNU's info viewer. This is copied into the `info' path of your system.
allegro.cfg: Contains configuration settings for your system when the hardware autodetection fails. You can either copy this file and edit the contents manually or you can use Allegro's setup configuration program (in the `setup' directory) to create this file. Recommended location is `[/usr/local]/etc/allegro.cfg'.

You can find more information about some of these files and other suggestions in the chapter "Unix specifics" of the main Allegro manual.

Using Allegro

The options for linking with Allegro are quite complicated, since for static versions of the library, depending on how it was configured, it may need to pull in other libraries (X, SVGAlib), as well as just Allegro itself.

To avoid you having to work out the right linker commands for yourself, the installation creates a script, allegro-config, that will print out a suitable command line. You can use this inside a backtick command substitution, for example:

      gcc myfile.c -o myprogram `allegro-config --libs`

Or if you want to build a debug version of your program, assuming that you have installed the debug version of Allegro:

      gcc myfile.c -o myprogram `allegro-config --libs debug`

Unix newbies, take note that these are ` backticks, not normal ' quotes!

There are also switches for printing out the Allegro version number, overriding the install paths, and selecting between shared and static libraries, in case you installed both. Run allegro-config without any arguments for a full list of options.

You can also use pkg-config instead, for example:

      gcc myfile.c -o myprogram `pkg-config --libs allegro loadpng`

As shown, there are pkg-config files for the bundled addons as well.

Don't forget that you need to use the END_OF_MAIN() macro right after your main() function!

Setting an X11 icon

You can set the X11 icon for your application to use. To do this, you need to include the icon in .xpm format and then point the symbol allegro_icon to the .xpm data before calling set_gfx_mode(). Alternatively, you can use the xfixicon.sh shellscript to produce a C file that will do this for you automatically when you link it with your project. No other steps are required. The xfixicon.sh utility will also accept bitmaps that are not in .xpm format, interpreting magic pink as transparent. You will need to have the ImageMagick tools installed for this to work.

What if you're not root?

Allegro can be installed on a system where you don't have root privileges. Using the standard configure script option `--prefix' you can change the target directories for installation -- for example, you can write:

      cmake -DCMAKE_INSTALL_PREFIX=$HOME ..

Then binaries will be installed to the `bin' subdirectory of your home directory, libraries to `lib', etc. Now you need to set up your system so that it knows where to find a few things, if this has not been done already. You might want to add these commands to your .bash_profile or similar startup script. If you use a csh-style shell, you want to use `setenv', not `export'.

Your PATH must include the `bin' directory:

      export PATH=$PATH:$HOME/bin

If you are using Allegro as a shared library, you need to tell the dynamic loader where to find the Allegro libraries:

      export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/lib

GCC needs to know where to find header and library files:

      export C_INCLUDE_PATH=$C_INCLUDE_PATH:$HOME/include
      export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:$HOME/include
      export LIBRARY_PATH=$LIBRARY_PATH:$HOME/lib

Note: in fact `allegro-config' can handle the last step for you, if you use it for compilation as well as linking:

      gcc -c mygame.c `allegro-config --cflags`
      gcc -o mygame mygame.o `allegro-config --libs`

But, it's better to set the environment variables too. Most people don't tend to bother with `allegro-config' when compiling.

Alternatively, you can get the required environment changes from allegro-config, by typing at a shell prompt:

      allegro-config --env

You can catenate the output to your .bash_profile, which is pretty much like adding all of the above commands. Note that `allegro-config' itself is in the `bin' directory of the installation, so either make sure that directory is in your path before running `allegro-config' or specify the path exactly, for example:

      ~/bin/allegro-config --env >> ~/.bash_profile

Notes on drivers

System:: On initialisation, Allegro will try to connect to an X server. If it can't find one, it will give up and try to use some different system driver instead (such as the Linux console driver, if it is enabled). This means that to run it in X mode, you must either launch your programs from inside an X session, or have set the DISPLAY environment variable to indicate what server you would like to use.
Graphics:: There are two different X graphics drivers: GFX_XWINDOWS uses only standard X calls, while GFX_XDGA2 uses the XFree86 DGA 2.0 extension (shipped with XFree86 4.0.x) which allows it to write directly to the screen surface, and use hardware acceleration if available. It is normally much faster than the standard X mode, but requires root permissions and will not work remotely. Note that DGA2 is deprecated now.
If your program requests a different color depth to the current X display, Allegro will emulate the depth you asked for, so that your program will still work, albeit more slowly than if the color depths were identical. To find out whether this emulation is taking place, look at the gfx_driver->desc field (which is displayed in the middle of the screen by the tests/test program). If this says "matching", the color formats are identical, so no conversions are required. If it says "fast", some simple conversions are taking place, but nothing too painful. If it says "slow", you are in trouble :-) This is not valid for the DGA 2.0 driver, as it'll always change the video mode to the specified resolution and color depth.

Irix Notes

If the Irix compiler spits strange lines such as the following when compiling your Allegro program:

      include/allegro/alcompat.h:59: conflicting types for `ceilf'
      /usr/include/math.h:311: previous declaration of `ceilf'
      include/allegro/alcompat.h:60: conflicting types for `floorf'
      /usr/include/math.h:333: previous declaration of `floorf'
      include/allegro/alcompat.h:63: conflicting types for `tanf'
      /usr/include/math.h:176: previous declaration of `tanf'
      include/allegro/alcompat.h:64: conflicting types for `acosf'
      /usr/include/math.h:106: previous declaration of `acosf'
      include/allegro/alcompat.h:65: conflicting types for `asinf'
      /usr/include/math.h:116: previous declaration of `asinf'

then you should #define ALLEGRO_NO_FIX_ALIASES prior to the #include <allegro.h> line.