$Id$

    Blender CMake build system
    ============================

    Contents
    ---------------

    1. Introduction
    2. Obtaining CMake
    3. Obtaining Dependencies
    4. Deciding on a Build Environment
    5. Configuring the build for the first time
    6. Configuring the build after CVS updates
    7. Specify alternate Python library versions and locations


    1. Introduction
    ---------------

    This document describes general usage of the new CMake scripts. The
    inner workings will be described in blender-cmake-dev.txt (TODO).

    2. Obtaining CMake
    ------------------

    CMake for can either be downloaded using your favorite package manager 
    or is also available from the CMake website at http://www.cmake.org 
    The website also contains some documentation on CMake usage but I found
    the man page alone pretty helpful. 

    3. Obtaining Dependencies
    -------------------------

    Check from the page
    http://www.blender.org/cms/Getting_Dependencies.135.0.html 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.

    4. Deciding on a Build Environment
    ----------------------------------

    To build Blender with the CMake scripts you first need to decide which
    build environment you feel comfortable with. This decision will also be
    influenced by the platform you are developing on. The current implementation
    have been successfully used to generate build files for the following 
    environments:

    1. Microsoft Visual Studio 2005. There is a free version available
       at http://msdn.microsoft.com/vstudio/express/visualc/.

    2. Xcode on Mac OSX

    3. Unix Makefiles (On Linux and Mac OSX): CMake actually creates make 
       files which generates nicely color coded output and a percentage 
       progress indicator.


    5. Configuring the build for the first time
    -------------------------------------------

    CMake allows one to generate the build project files and binary objects
    outside the source tree which can be pretty handy in working and experimenting
    with different Blender configurations (Audio/NoAudio, GameEngine/NoGameEngine etc.)
    while maintaining a clean source tree. It also makes it possible to generate files
    for different build systems on the same source tree. This also has benefits for 
    general CVS management for the developer as patches and submit logs are much cleaner.

    Create a directory outside the blender source tree where you would like to build
    Blender (from now on called $BLENDERBUILD). On the commandline you can then run
    the cmake command to generate your initial build files. First just run 'cmake' which
    will inform you what the available generators are. Thn you can run 
    'cmake -G generator $BLENDERSOURCE' to generate the build files. Here is an example 
    of all this for Xcode:

        % mkdir $BLENDERBUILD
        % cd $BLENDERBUILD
        % cmake

		...
		...
		--version [file]            = Show program name/version banner and exit.

		Generators

		The following generators are available on this platform:
		  KDevelop3                   = Generates KDevelop 3 project files.
		  Unix Makefiles              = Generates standard UNIX makefiles.
		  Xcode                       = Generate XCode project files.



        % cmake -G Xcode $BLENDERSOURCE
		...
		...
		-- Configuring blender
		-- Configuring blenderplayer
		-- Configuring done
		-- Generating done
		-- Build files have been written to: $BLENDERBUILD 

    This will generate the build files with default values. Specific features can
    be enabled or disabled by running the ccmake "GUI" from $BLENDERBUILD as follows:

        % ccmake $BLENDERSOURCE

    A number of options appear which can be changed depending on your needs and
    available dependencies (e.g. setting WITH_OPENEXR to OFF will disable support
    for OpenEXR). It will also allow you to override default and detected paths 
    (e.g. Python directories) and compile and link flags. When you are satisfied
    used ccmake to re-configure the build files and exit.

    It is also possible to use the commandline of 'cmake' to override certain
    of these settings. 

    6. Configuring the build after CVS updates
    ------------------------------------------

    The $BLENDERBUILD directory maintains a file called CMakeCache.txt which 
    remembers the initial run's settings for subsequent generation runs. After
    every CVS update it may be a good idea to rerun the generation before building
    Blender again. Just rerun the original 'cmake' run to do this, the settings
    will be remembered. For the example above the following will do after every
    'cvs up':

        % cmake -G Xcode $BLENDERSOURCE

    7. Specify alternate Python library versions and locations
    ----------------------------------------------------------
    
    The commandline can be used to override detected/default settings, e.g:
 
    On Unix: 
      cmake -D PYTHON_LIB=/usr/local/lib/python3.1/config/libpython3.1.so -D PYTHON_INC=/usr/local/include/python3.1 -G "Unix Makefiles" ../blender
    On Macs: 
      cmake -D PYTHON_INC=/System/Library/Frameworks/Python.framework/Versions/3.1/include/python3.1 -G Xcode ../blender

    Mote that this should only be needed once per build directory generation because it will keep the overrides in CMakeCache.txt for subsequent runs.



    To be continued...

    TODO's
    ------

    1. Get CMake to create proper distribution directories for the various platforms
       like scons does.
    2. Investigate the viability of using CPack to package installs automatically.
    3. Refine this document and write detailed developer's document.
    4. Make sure all options (ffmpeg, openexr, quicktime) has proper CMake support
       on the various platforms.    

    /Jacques Beaurain (jbinto)