Module API_intro

The Blender Python API Reference

Top Module:

• Blender

Submodules:

• Armature
  • NLA
  • Action
• BezTriple (*)
• BGL
• Camera
• Curve
• Draw
• Effect
• Geometry (*)
• Group (*)
• Image
• Ipo (*)
  • IpoCurve (*)
• Key (*)
• Lamp
• Lattice
• Library
• Material (*)
• Mathutils (*)
• Mesh (*)
  • MeshPrimitives (*)
• Metaball
• Modifier (*)
• NMesh (*)
• Noise
• Object (*)
  • Pose
  • Constraint (*)
  • ActionStrips (*)
• Registry
• Scene
  • Radio
  • Render
• Sound
• Text
• Text3d
  • Font
• Texture (*)
• TimeLine
• Types
• Window
  • Theme
• World
• sys

Additional information:

• Special features:
  • scripts: registering in menus, documenting, configuring (new);
  • command line examples (new);
  • script links (*), space handler script links, Group module (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 Python, an impressive high level, multi-paradigm, open source language. Newcomers are recommended to start with the tutorial that comes with it.

Scripting and 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: 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 background mode: use the '-b' flag (the order is important): blender -b <blendfile> -P <scriptname>. <blendfile> can be any .blend file, including the default .B.blend that is in Blender's home directory 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 (Text) and link other scripts to objects and events, see 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 Blender.Run module function.

Interaction with users:

• 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, check here);
• 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 Blender.Run());
• use external Python libraries, if available.

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 Blender.Save, Blender.Load, Blender.Quit and the Library and 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 Window) don't work here. If you need those, use an ONLOAD script link (see Scene.Scene.addScriptLink) instead -- it's also possible to use a command line script to write or set an ONLOAD script link. Check the Blender.mode module var to know if Blender is being executed in "background" or "interactive" mode.

Demo mode:

The Game Engine API:

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).

A note to newbie script writers:

Version: 2.42

Author: The Blender Python Team

Notes:

• this documentation was generated by epydoc, which can output html and pdf. For pdf it requires a working LaTeX environment.
• 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 blender.org.

Requires: Blender 2.42 or newer.

See Also:

www.blender3d.org: main site, www.blender.org: documentation and forum, www.elysiun.com: user forum, projects.blender.org, blender architecture: blender architecture document, www.python.org, www.python.org/doc, en.wikibooks.org/wiki/Blender_3D:_Blending_Into_Python>: User contributed documentation, featuring a blender/python cookbook with many examples.