API • Page 29 of 31 • B3D

Selecting objects (meshes) in Blender 2.8 Python API

Leave a Comment / Blender 3D / Nikita / 06.02.2019

According to Blender 2.8 Python API changes mesh (object) can be selected with using getters and setters.

When trying to check the selected status of the mesh through the “bpy.context.active_object.select” property, Blender throws an error:

AttributeError: ‘Object’ object has no attribute ‘select’

To check whether an object is selected in Blender 2.8 use a getter:

bpy.context.active_object.select_get()
# True

1 2	bpy.context.active_object.select_get() # True

To select an object in Blender 2.8 use a setter:

bpy.context.active_object.select_set(state=True)

1	bpy.context.active_object.select_set(state=True)

To unselect an object use the same setter:

bpy.context.active_object.select_set(state=False)

1	bpy.context.active_object.select_set(state=False)

Porting add-on from Blender 2.7 to Blender 2.8

Leave a Comment / Blender 3D / Nikita / 28.01.2019

In the latest version 2.8 of Blender developers have made many changes in API, so all the scripts and add-ons written for earlier Blender versions (2.7 and below) have stopped working. To run your add-ons in the new Blender 2.8, you need to port them – correct their code to work properly with the new Blender API.

To enable your add-on in Blender 2.80 you have to make the following changes in code:

Porting add-on from Blender 2.7 to Blender 2.8Read More »

How to check if Blender object property/attribute is read-only

Leave a Comment / Blender 3D / Nikita / 14.12.2018

To check is an attribute/property of any Blender object (mesh, node, modifier, etc.) read-only:

With the is_property_readonly function, execute the following command:

<object> .is_property_readonly (‘<property name>’)

Through the rna structure, execute the following command:

<object> .bl_rna.properties [‘<property name>’]. is_readonly

For example, for the “is_editmode” mesh property (is the mesh in edit mode or not):

bpy.context.active_object.data.is_property_readonly('is_editmode')

# True


bpy.context.active_object.data.bl_rna.properties['is_editmode'].is_readonly

# True

bpy.context.active_object.data.is_property_readonly('is_editmode')

# True

bpy.context.active_object.data.bl_rna.properties['is_editmode'].is_readonly

# True

How to find out in what version of Blender the blend file was saved

Leave a Comment / Blender 3D / Nikita / 19.11.2018

To check in what version of Blender the blend file was saved:

Open your file in Blender
In the Python Console window execute the following command:

bpy.data.version

1	bpy.data.version

Or open the blend file in any text editor, for example in Notepad++. The Blender version will be listed in the first 15 characters.

Also, the version of the open blend file can be viewed in the Outliner window in the Data Blocks group:

How to get the version of the add-on installed in Blender

Leave a Comment / Blender 3D / Nikita / 12.11.2018

A complete list of add-ons installed in Blender we can get using the addon_utils:

import addon_utils
print(addon_utils.modules()[:])

# <module 'space_view3d_3d_navigation' from ...

import addon_utils

print(addon_utils.modules()[:])

# <module 'space_view3d_3d_navigation' from ...

Having the add-ons list, we can get the version of the desired add-on by its name with the following code:

import addon_utils
print([addon.bl_info.get('version', (-1,-1,-1)) for addon in addon_utils.modules() if addon.bl_info['name'] == 'ADD-ON_NAME'][0])

# (1,4,0)

import addon_utils

print([addon.bl_info.get('version', (-1,-1,-1)) for addon in addon_utils.modules() if addon.bl_info['name'] == 'ADD-ON_NAME'][0])

# (1,4,0)

Where the ADD-ON_NAME is the name of the desired add-on.

If the add-on is missing a version indication, the default result will be returned.

# (-1,-1,-1)

1	# (-1,-1,-1)

Learning loops

1 Comment / Blender 3D / Nikita / 26.06.2018

In general, the “loop” is usually a sequential selection of several points, edges or polygons of a mesh.

However, there is an element in the mesh structure, which is also called a “loop”. It is a combination of one vertex with one edge of the mesh. Let’s try to learn what these “loops” are for.

Learning loopsRead More »

How to pass command line arguments to a Blender python script or add-on

Leave a Comment / Blender 3D / Nikita / 17.04.2018

When starting Blender from the console it processes all parameters passed through the command line. However, some scripts and add-ons for proper work may require specifying their unique command line arguments. If you specify such additional parameters in the command line, Blender will also try to process them, which is likely to result in an error. Blender provides a special way to exclude such arguments from own processing.

How to pass command line arguments to a Blender python script or add-onRead More »

Creating radio buttons in the Blender add-ons interface

3 Comments / Blender 3D / Nikita / 09.02.2018

State switches so-called “radio buttons” are used in the case to limit the choice by one value from several available ones. There are a lot of such buttons in the Blender interface, for example, switching between RGB and BW rendering modes or setting the texture mapping mode. Such buttons can be created in the Blender add-ons interface too.

Let’s create our own radio button switcher.

Creating radio buttons in the Blender add-ons interfaceRead More »

How to programmatically check if the operator is registered in Blender API

Leave a Comment / Blender 3D / Nikita / 25.12.2017

Single add-on or script can contain several different operators, and not all of them may be registered in the API by the register() function. To verify that the required operator is registered in the Blender API, run the following command:

hasattr(bpy.types, bpy.ops._operator_bl_idname_.idname())

1	hasattr(bpy.types, bpy.ops._operator_bl_idname_.idname())

Where:

_operator_bl_idname_ – the text value of the bl_idname operator property.

For example for an operator:

class TestOperator(bpy.types.Operator):
    bl_idname = 'test.operator'
    bl_label = 'Test operator'

    def execute(self, context):
        pass

class TestOperator(bpy.types.Operator):

bl_idname = 'test.operator'

bl_label = 'Test operator'

def execute(self, context):

pass

the command will look like this:

hasattr(bpy.types, bpy.ops.test.operator.idname())

1	hasattr(bpy.types, bpy.ops.test.operator.idname())

How to programmatically check if the Blender add-on is registered

Leave a Comment / Blender 3D / Nikita / 25.12.2017

To start working every Blender add-on must be registered by setting up the checkbox before add-on name in the User Preferences window – Add-ons page.

To programmatically find out if the required add-on is registered, run the following command:

'add-on_name' in the file bpy.context.user_preferences.addons

1	'add-on_name' in the file bpy.context.user_preferences.addons

Where:

add-on_name – the name of the add-on file (without the .py extension) or the name of the add-on package, if it was installed from the package.