blender-archive/source/blender/python/api2_2x/doc/API_intro.py

# This is not a real module, it's simply an introductory text.

"""
The Blender Python API Reference
================================

 An asterisk (*) means the module has been updated.

 Top Module:
 -----------

  - L{Blender}

 Submodules:
 -----------
  - L{Armature} (work in progress)
     - L{NLA}
  - L{BGL}
  - L{Camera}
  - L{Curve}
  - L{Draw}
  - L{Effect}
  - L{Image}
  - L{Ipo}
  - L{Key} (*)
  - L{Lamp}
  - L{Lattice}
  - L{Library}
  - L{Material} (*)
  - L{Mathutils} (*)
  - L{Mesh} (*)
  - L{Metaball}
  - L{NMesh} (*)
  - L{Noise}
  - L{Object} (*)
  - L{Registry}
  - L{Scene}
     - L{Radio}
     - L{Render}
  - L{Sound}
  - L{Text}
  - L{Text3d}
     - L{Font}
  - L{Texture} (*)
  - L{TimeLine}
  - L{Types}
  - L{Window}
     - L{Theme}
  - L{World}
  - L{sys<Sys>}

 Additional information:
 -----------------------

  - L{Special features<API_related>}:
    - scripts: registering in menus, documenting, configuring (new);
    - command line examples (new);
    - script links (*), space handler script links (new).

Introduction:
=============

 This reference documents the Blender Python API, a growing collection of
 Python modules (libraries) that give access to part of the program's internal
 data and functions.
 
 Through scripting Blender can be extended in real-time via
 U{Python <www.python.org>}, an impressive high level, multi-paradigm, open
 source language.  Newcomers are recommended to start with the tutorial that
 comes with it.

 This opens many interesting possibilities, ranging from automating repetitive
 tasks to adding new functionality to the program: procedural models,
 importers and exporters, even complex applications and so on.  Blender itself
 comes with some scripts, but many others can be found in the Scripts & Plugins
 sections and forum posts at the Blender-related sites listed below.

Scripting and Blender:
======================

These are the basic ways to execute scripts in Blender:

 1. They can be loaded or typed as text files in the Text Editor window, then
 executed with ALT+P.
 2. Via command line: C{blender -P <scriptname>} will start Blender and execute
 the given script.  <scriptname> can be a filename in the user's file system or
 the name of a text saved in a .blend Blender file:
 'blender myfile.blend -P textname'.
 3. Via command line in I{background mode}: use the '-b' flag (the order is
 important): C{blender -b <blendfile> -P <scriptname>}.  <blendfile> can be any
 .blend file, including the default .B.blend that is in Blender's home directory
 L{Blender.Get}('homedir'). In this mode no window will be opened and the
 program will leave as soon as the script finishes execution.
 4. Properly registered scripts can be selected directly from the program's
 menus.
 5. Scriptlinks: these are also loaded or typed in the Text Editor window and
 can be linked to objects, materials or scenes using the Scriptlink buttons
 tab.  Script links get executed automatically when their events (ONLOAD,
 REDRAW, FRAMECHANGED) are triggered.  Normal scripts can create (L{Text}) and
 link other scripts to objects and events, see L{Object.Object.addScriptLink},
 for example.
 6. A script can call another script (that will run in its own context, with
 its own global dictionary) with the L{Blender.Run} module function.


Interaction with users:
-----------------------

 Scripts can:
  - simply run and exit;
  - pop messages, menus and small number and text input boxes;
  - draw graphical user interfaces (GUIs) with OpenGL calls and native
    program buttons, which stay there accepting user input like any other
    Blender window until the user closes them;
  - attach themselves to a space's event or drawing code (aka space handlers,
    L{check here<API_related>});
  - make changes to the 3D View (set visible layer(s), view point, etc);
  - grab the main input event queue and process (or pass to Blender) selected
    keyboard, mouse, redraw events -- not considered good practice, but still
    available for private use;
  - tell Blender to execute other scripts (see L{Blender.Run}());
  - use external Python libraries, if available.

 You can read the documentation for the L{Window}, L{Draw} and L{BGL} modules
 for more information and also check the Python site for external modules that
 might be useful to you.  Note though that any imported module will become a
 requirement of your script, since Blender itself does not bundle external
 modules.

Command line mode:
------------------

 Python was embedded in Blender, so to access BPython modules you need to
 run scripts from the program itself: you can't import the Blender module
 into an external Python interpreter.

 On the other hand, for many tasks it's possible to control Blender via
 some automated process using scripts.  Interested readers should learn about
 features like "OnLoad" script links, the "-b <blendfile>" (background mode)
 and "-P <script>" (run script) command line options and API calls like
 L{Blender.Save}, L{Blender.Load}, L{Blender.Quit} and the L{Library} and
 L{Render} modules. 

 Note that command line scripts are run before Blender initializes its windows
 (and in '-b' mode no window will be initialized), so many functions that get
 or set window related attributes (like most in L{Window}) don't work here.  If
 you need those, use an ONLOAD script link (see L{Scene.Scene.addScriptLink})
 instead -- it's also possible to use a command line script to write or set an
 ONLOAD script link.  Check the L{Blender.mode} module var to know if Blender
 is being executed in "background" or "interactive" mode.

 L{Click here for command line and background mode examples<API_related>}.


Demo mode:
----------

 Blender has a demo mode, where once started it can work without user
 intervention, "showing itself off".  Demos can render stills and animations,
 play rendered or real-time animations, calculate radiosity simulations and
 do many other nifty things.  If you want to turn a .blend file into a demo,
 write a script to run the show and link it as a scene "OnLoad" scriptlink.
 The demo will then be played automatically whenever this .blend file is
 opened, B{unless Blender was started with the "-y" parameter}.

The Game Engine API:
--------------------

 Blender has a game engine for users to create and play 3d games.  This
 engine lets programmers add scripts to improve game AI, control, etc, making
 more complex interaction and tricks possible.  The game engine API is
 separate from the Blender Python API this document references and you can
 find its own ref doc in the docs section of the main sites below.

Blender Data Structures:
------------------------

 Programs manipulate data structures.  Blender python scripts are no exception.
 Blender uses an Object Oriented architecture.  The BPython interface tries to
 present Blender objects and their attributes in the same way you see them
 through the User Interface (the GUI).  One key to BPython programming is
 understanding the information presented in Blender's OOPS window where Blender
 objects and their relationships are displayed.

 Each Blender graphic element (Mesh, Lamp, Curve, etc.) is composed from two
 parts: an Object and ObData. The Object holds information about the position,
 rotation and size of the element.  This is information that all elements have
 in common.  The ObData holds information specific to that particular type of
 element.  

 Each Object has a link to its associated ObData.  A single ObData may be
 shared by many Objects.  A graphic element also has a link to a list of
 Materials.  By default, this list is associated with the ObData.

 All Blender objects have a unique name.  However, the name is qualified by the
 type of the object.  This means you can have a Lamp Object called Lamp.001
 (OB:Lamp.001) and a Lamp ObData called Lamp.001 (LA:Lamp.001).

 For a more in-depth look at Blender internals, and some understanding of why
 Blender works the way it does, see the U{Blender Architecture document
 <http://www.blender3d.org/cms/Blender_Architecture.336.0.html>}.


A note to newbie script writers:
--------------------------------

 Interpreted languages are known to be much slower than compiled code, but for
 many applications the difference is negligible or acceptable.  Also, with
 profiling (or even simple direct timing with L{Blender.sys.time<Sys.time>}) to
 identify slow areas and well thought optimizations, the speed can be
 I{considerably} improved in many cases.  Try some of the best BPython scripts
 to get an idea of what can be done, you may be surprised.

@author: The Blender Python Team
@requires: Blender 2.37 or newer.
@version: 2.37
@see: U{www.blender3d.org<http://www.blender3d.org>}: main site
@see: U{www.blender.org<http://www.blender.org>}: documentation and forum
@see: U{www.elysiun.com<http://www.elysiun.com>}: user forum
@see: U{projects.blender.org<http://projects.blender.org>}
@see: U{blender architecture<http://www.blender3d.org/cms/Blender_Architecture.336.0.html>}: blender architecture document
@see: U{www.python.org<http://www.python.org>}
@see: U{www.python.org/doc<http://www.python.org/doc>}
@note: this documentation was generated by epydoc, which can output html and
   pdf.  For pdf it requires a working LaTeX environment.

@note: the official version of this reference guide is only updated for each
   new Blender release.  But you can build the current CVS
   version yourself: install epydoc, grab all files in the
   source/blender/python/api2_2x/doc/ folder of Blender's CVS and use the
   epy_docgen.sh script also found there to generate the html docs.
   Naturally you will also need a recent Blender binary to try the new
   features.  If you prefer not to compile it yourself, there is a testing
   builds forum at U{blender.org<http://www.blender.org>}.
"""