
    Blenders SCons build scripts
    ============================

    Introduction
    ------------

    Since the beginning of 2004 Blender has had the SCons system as a
    build option. SCons is a Python-based, accurate build system. The
    scripts that were implemented in the first iteration worked, but
    the system grew quickly into such a state that maintaining it became
    a nightmare, and adding new features was just horrible, leading to
    many hacks without much sense in the overall structure.

    The rewrite has been waiting for a long time. Jonathan Jacobs provided
    a first overhaul of the scripts, which I used in the first phase of
    the rewrite. To make the system as maintainable as possible I made
    some radical changes, but thanks go to Jonathan for providing me
    with the patch to get started.

    This document describes the usage of the new SCons scripts. The
    inner workings are described in scons-dev.txt.

    Building Blender
    ----------------

    To build Blender with the SCons scripts you need a full Python
    install, version 2.4 or later (http://www.python.org). We already provide
    a scons-local installation, which can be found in the scons/ subdirectory.
    This document uses the scons-local installation for its examples.

    Check from the page
    http://www.blender.org/development/building-blender/getting-dependencies/
    that you have all dependencies needed for building Blender. Note that for
    windows many of these dependencies already come in the lib/windows module
    from CVS.

    In the base directory of the sources (from now on called $BLENDERHOME)
    you'll see a file named SConstruct. This is the entry point for the
    SCons build system. In a terminal, change to this directory. To just
    build, start the SCons entry script on Windows (will be used for the remainder
    of this document):

        % python scons\scons.py

    On a Unix-compatible system it would be

        % python ./scons/scons.py

    This will start the build process with default values. Depending
    on your platform you may see color in your output (non-Windows
    machines). In the the beginning an overview of targets and arguments
    from the command-line is given, then all libraries and binaries to
    build are configured.

    The build uses BF_BUILDDIR to build into and BF_INSTALLDIR to
    finally copy all needed files to get a proper setup. The BF_DOCDIR is
    used to generate Blender Python documentation files to. These
    variables have default values for every platform in
    $BLENDERHOME/config/(platform)-config.py. After the build successfully
    completes, you can find everything you need in BF_INSTALLDIR.

    If you want to create the installer package of Blender on Windows you'll
    need to install nullsoft scriptable install system from http://nsis.sf.net.
    As an extra dependency, you need the MoreInfo plugin too. The creation of
    the installer is tied into the build process and can be triggered with:

        % python scons\scons.py nsis


    Configuring the build
    ---------------------

    The default values for your platform can be found in the directory
    $BLENDERHOME/config. Your platform specific defaults are in
    (platform)-config.py, where platform is one of:

        - linux, for machines running Linux
        - win32-vc, for Windows machines, compiling with a Microsoft compiler
        - win32-mingw, for Windows machines, compiling with the MingW compiler
        - darwin, for OS X machines
        (TBD: add cygwin, solaris and freebsd support)

    These files you will normally not change. If you need to override
    a default value, make a file called  $BLENDERHOME/user-config.py, and copy
    settings from the config/(platform)-config.py that you want to change. Don't
    copy the entire file (unless explicitely stated in the configuration file),
    because you may not get updated options you don't change yourself, which may
    result in build errors.

    You can use BF_CONFIG argument to override the default user-config.py
    check. This is just like the user-config.py, but just with another name:

        % python scons\scons.py BF_CONFIG=myownsettings

    If you want to quickly test a new setting, you can give the option
    also on the command-line:

        % python scons\scons.py BF_BUILDDIR=../mybuilddir WITH_BF_OPENEXR=0

    This command sets the build directory to BF_BUILDDIR and disables
    OpenEXR support.

    If you need to know what can be set through the command-line, run
    scons with -h:

        % python scons\scons.py -h

    This command will print a long list with settable options and what
    every option means. Many of the default values will be empty, and
    from a fresh checkout without a user-config.py the actual values
    are the defaults as per $BLENDERHOME/config/(platform)-config.py
    (unless you have overridden any of them in your
    $BLENDERHOME/user-config.py).

    NOTE: The best way to avoid confusion is the
    copy $BLENDERHOME/config/(platform)-config.py to
    $BLENDERHOME/user-config.py. You should NEVER have to modify
    $BLENDERHOME/config/(platform)-config.py

    Configuring the output
    ----------------------

    This rewrite features a cleaner output during the build process. If
    you need to see the full command-line for compiles, then you can
    change that behaviour. Also the use of colors can be changed:

        % python scons\scons.py BF_FANCY=0

    This will disable the use of colors.

        % python scons\scons.py BF_QUIET=0

    This will give the old, noisy output. Every command-line per
    compile is printed out in its full glory. This is very useful when
    debugging problems with compiling, because you can see what the
    included paths are, what defines are given on the command-line,
    what compiler switches are used, etc.

    Compiling Only Some Libraries
    -----------------------------
    
    Our implementation now has support for specifying a list of libraries that are
    exclusively compiled, ignoring all other libraries.  This is invoked 
    with the BF_QUICK arguments; for example:
    
        % python scons\scons.py BF_QUICK=src,bf_blenkernel
    
    Note that this not the same as passing a list of folders as in the 
    makefile's "quicky" command.  In Scons, all of Blender's code modules
    are in their own static library; this corresponds to one-lib-per-folder 
    in some cases (especially in blender/source/blender).
    
    To obtain a list of the libraries, simple fire up scons and CTRL-C out once 
    it finishes configuring (and printing to the console) the library list.
    
    Compiling Libraries With Debug Profiling
    ----------------------------------------
    
    Scons has support for specifying a list of libraries that are compiled
    with debug profiling enabled.  This is implemented in two commands:
    BF_QUICKDEBUG which is a command-line argument and BF_DEBUG_LIBS, which goes
    in your user-config.py
    
    BF_QUICKDEBUG is similar to BF_QUICK:
    
        % python scons\scons.py BF_QUICKDEBUG=src,bf_blenkernel,some-other-lib
    
    To use BF_DEBUG_LIBS, put something like the following in you user-config.py:
    
        BF_DEBUG_LIBS = ['bf_blenlib', 'src', 'some_lib']
        
    For instructions on how to find the names of the libraries (folders) you 
    wish to use, see the above section.  Note that the command BF_DEBUG 
    (see below) will override these settings and compile ALL of Blender with
    debug symbols.  Also note that BF_QUICKDEBUG and BF_DEBUG_LIBS are combined;
    for example, setting BF_QUICKDEBUG won't overwrite the contents of BF_DEBUG_LIBS.

    Supported toolset
    -----------------

    WINDOWS

        * msvc, this is a full install of Microsoft Visual C++. You'll
        likely have the .NET Framework SDK, Platform SDK and DX9 SDK
        installed * mstoolkit, this is the free MS VC++ 2003 Toolkit. You
        need to verify you have also the SDKs installed as mentioned
        for msvc.  * mingw, this is a minimal MingW install. TBD: write
        proper instructions on getting needed packages.

    On Windows with all of the three toolset installed you need to
    specify what toolset to use

        % python scons\scons.py BF_TOOLSET=msvc
        % python scons\scons.py BF_TOOLSET=mingw

    LINUX and OS X

    Currently only the default toolsets are supported for these platforms,
    so nothing special needs to be told to SCons when building. The
    defaults should work fine in most cases.

    Examples
    --------

    Build Blender with the defaults:

        % python scons\scons.py

    Build Blender, but disable OpenEXR support:

        % python scons\scons.py WITH_BF_OPENEXR=0

    Build Blender, enable debug symbols:

        % python scons\scons.py BF_DEBUG=1

    Build Blender, install to different directory:

        % python scons\scons.py BF_INSTALLDIR=../myown/installdir

    Build Blender in ../myown/builddir and install to ../myown/installdir:

        % python scons\scons.py BF_BUILDDIR=../myown/builddir BF_INSTALLDIR=../myown/installdir

    Clean BF_BUILDDIR:

        % python scons\scons.py clean

    /Nathan Letwory (jesterKing)
