API

Active objects access

How to access the active (selected) objects through the Blender Python API from scripts/add-ons:

  1. The active window (in which current action occurs):

  1. The active scene:

  1. The active (selected) mesh:

  1. The active (selected) material node (in the NODE_EDITOR window):

  1. The active (selected) material node (in the COMPOSITING window):

  1. The current text in TEXT_EDITOR window:

  1. The active (selected) UV-Map:

Working with MySQL database from Blender

Storing data in a remote database has become common practice in the development of software products. Blender is no exception. Writing scripts and add-ons, the developer may need to access the database to retrieve from it or write to it the necessary information. MySQL today is one of the most common and widely available databases and is well suited for working with Blender.

The interaction between Blender and MySQL database through the Blender Python API is not difficult, but it needs some preparation before stating:

Binding to timeline frames

Sometimes when creating an animation it is necessary to perform some actions according to the timeline or, the same, to the current animation frame number. Binding animation to timeline frames in Blender is possible using the built-in Python API.

As an example, let’s make a simple animation which turns one of the letters of any text from lowercase to uppercase in series.

Creating multifile add-on for Blender

In the development of complex add-ons with large code volume storing all the code in a single file is inappropriate. When a single file contains logically unrelated classes, functions, and datasets, it is difficult to read, debug, find the necessary code pieces, reuse code. Such code layout is considered as very bad programming tone.

Blender Python supports modular system that allows subdividing logical code parts of the add-on into different files, and then connect them to use. Even if you have never thought about modules, creating scripts or add-ons, you have already used them – any code stored in the *.py file is a separate independent module. Just your addon consists of only one module. Complex add-ons may consist of several tens of modules.

Multifile add-on
Multifile add-on

Creating Blender Add-ons variables with values saved in blend-files

All user-defined classes (panels, operators), registered in Blender API, exists only during Blender runs. After program close they are deleted from memory. Therefore, if some variables are defined in user classes, all of them will be reset after Blender restart.

However, sometimes it is necessary to use in Blender add-on variables with values that not be lost in the process of program restarting. To retain variables values, it needs to wrap them into special class – property, and attach to any object whose properties are stored in * .blend file.

Variables in Blender API operator classes

User defined operator classes, inherited from bpy.types.Operator, are static. Accordingly, only static variables can be defined in them.

Static variable sampleVar definition in SampleClass class: