Python • Page 28 of 33 • B3D

Class for creating nodes by type

Leave a Comment / Blender 3D / Nikita / 03.07.2019

Class for quick node creation by their type.

Code by Skarn.

class NodeTreeBuilder:

    def __init__( self
                 , node_tree : bpy.types.NodeTree
                 , x : float = -200
                 , y : float = -200
                 , delimeter : float = 300
                ):
        self._x = x
        self._y = y
        self.tree = node_tree
        self.delimeter = delimeter

        self.purge_tree()

    def purge_tree(self):
        for node in self.tree.nodes:
            self.tree.nodes.remove(node)

    def add_node(  self
                 , node_type : str
                 , node_name : str
                 , column : int
                 , row : int
                 , node_descr : str = ""
                ):

        node = self.tree.nodes.new(node_type)
        node.name = node_name
        node.label = node_descr if node_descr else node_name

        node.location = (self.delimeter * column + self._x, -self.delimeter * row + self._y)

        return node

class NodeTreeBuilder:

def __init__( self

, node_tree : bpy.types.NodeTree

, x : float = -200

, y : float = -200

, delimeter : float = 300

self._x = x

self._y = y

self.tree = node_tree

self.delimeter = delimeter

self.purge_tree()

def purge_tree(self):

for node in self.tree.nodes:

self.tree.nodes.remove(node)

def add_node( self

, node_type : str

, node_name : str

, column : int

, row : int

, node_descr : str = ""

node = self.tree.nodes.new(node_type)

node.name = node_name

node.label = node_descr if node_descr else node_name

node.location = (self.delimeter * column + self._x, -self.delimeter * row + self._y)

return node

Class for creating nodes by typeRead More »

How to protect your add-on from downloading through aggregators

2 Comments / Blender 3D / Nikita / 26.06.2019

With the Blender popularity growing, the number of add-ons created for it by third-party developers is growing too. A lot of high-quality professional add-ons are written for Blender now. Over time, the number of add-ons is becoming more and more. And on this wave aggregators appeared – programs and services independently searching for add-ons and allowing Blender users to install add-ons quickly, many at once, and bypassing add-on distribution channels selected by their authors. What caused a negative reaction of add-on developers.

How to protect your add-on from downloading through aggregatorsRead More »

How to detect if Local View is on in 3D View window

Leave a Comment / Blender 3D / Nikita / 21.06.2019

The following command returns the 3D View areas list with enabled Local View mode:

[area for area in bpy.context.screen.areas if area.type =='VIEW_3D' and area.spaces[0].local_view]

# [bpy.data.screens['Layout']...Area]

[area for area in bpy.context.screen.areas if area.type =='VIEW_3D' and area.spaces[0].local_view]

# [bpy.data.screens['Layout']...Area]

Changing objects visibility in the viewport and while rendering

Leave a Comment / Blender 3D / Nikita / 17.06.2019

The easiest way to hide and show rendering objects is to assign animation keys to them. To do this, move the cursor over the eye icon (visibility in the viewport) or camera (visibility when rendering) in the Outliner window, press the “i” key and then manage the created condition in the Graph Editor like the ordinary animation keys.

But this method is not always available. For example, we cannot assign visibility animation keys for collections, Blender will generate errors like:

“hide_viewport” property cannot be animated

“hide_render” property can not be animated

However, using the Blender Python API, we can control the visibility of such objects.

Changing objects visibility in the viewport and while renderingRead More »

Blender autocomplete modules

Leave a Comment / Blender 3D / Nikita / 27.05.2019

Nutti, the author of the “fake-bpy-modules” project, has made the installation of the Blender Python API autocomplete modules through the pip platform. Pip installation is faster and easier, but sometimes we just need to copy the autocomplete modules to our project but now they are not included in the Nutti’s GitHub.

Copies of the autocomplete modules for Blender versions 2.79 and 2.80 can be downloaded directly from here: https://github.com/Korchy/blender_autocomplete

How to get global vertex coordinates

Leave a Comment / Blender 3D / Nikita / 22.05.2019

To get the vertex coordinates in the scene global coordinate system when the object’s scale was not applied, we need to multiply the local vertex coordinates by the object world transformation matrix:

object = bpy.data.objects['_MY_OBJECT_']
v_local = object.data.vertices[_VERT_NUMBER_].co # local vertex coordinate
v_global = object.matrix_world @ v_local # global vertex coordinates

object = bpy.data.objects['_MY_OBJECT_']

v_local = object.data.vertices[_VERT_NUMBER_].co # local vertex coordinate

v_global = object.matrix_world @ v_local # global vertex coordinates

Class naming conventions in Blender 2.8 Python API

8 Comments / Blender 3D / Nikita / 20.05.2019

In Blender 2.8 API the requirements for the class and their identifiers naming are becoming tougher. The class name must match the following convention:

UPPER_CASE_{SEPARATOR}_mixed_case

1	UPPER_CASE_{SEPARATOR}_mixed_case

Where the {SEPARATOR} is two letters denoting the class belonging to a certain type (from which type the class is inherited):

HT – Header
MT – Menu
OT – Operator
PT – Panel
UL – UI list

The class identifier “bl_idname” mast match the class name.

Class naming conventions in Blender 2.8 Python APIRead More »

Changes in add-ons registration through the API in Blender 2.8

Leave a Comment / Blender 3D / Nikita / 29.03.2019

Add-on registration and removing were made with the “Window manager” (wm) in Blender 2.7 Python API:

bpy.ops.wm.addon_install(filepath='_path_to_addon', overwrite=True)

bpy.ops.wm.addon_enable(module='addon_name')

bpy.ops.wm.addon_remove(module='addon_name')

bpy.ops.wm.addon_install(filepath='_path_to_addon', overwrite=True)

bpy.ops.wm.addon_enable(module='addon_name')

bpy.ops.wm.addon_remove(module='addon_name')

In Blender 2.8 API add-on operators moved to the “preferences”:

bpy.ops.preferences.addon_install(filepath='_path_to_addon', overwrite=True)

bpy.ops.preferences.addon_enable(module='addon_name')

bpy.ops.preferences.addon_remove(module='addon_name')

bpy.ops.preferences.addon_install(filepath='_path_to_addon', overwrite=True)

bpy.ops.preferences.addon_enable(module='addon_name')

bpy.ops.preferences.addon_remove(module='addon_name')

3D Cursor location in Blender 2.8 Python API

Leave a Comment / Blender 3D / Nikita / 27.03.2019

3D-cursor location property

context.scene.cursor_location

1	context.scene.cursor_location

in Blender 2.8 API moved to “cursor” object

context.scene.cursor.location

1	context.scene.cursor.location

When trying to get the cursor location through the “context.scene.cursor_location” Blender throws an error:

‘Scene’ object has no attribute ‘cursor_location’

Add-on preferences panel

4 Comments / Blender 3D / Nikita / 25.03.2019

When developing add-ons it is often necessary to give an ability to set a number of parameters that affect the whole add-on work to the user. For example, the user can specify a directory for saving/loading files, set some default variables or switch between add-on modes. Of course, the interface for setting such parameters can be placed in the add-on panel, but it is better to place it in a separate add-on preferences panel, which is located in the “Preferences” window under the add-on installation panel.

The main advantage of the add-on preferences is that they don’t reset when Blender restarts. The user does not need to configure the add-on preferences each time, it’s enough to set the necessary parameters once, personalizing the add-on for convenient work.

Let’s create an add-on and define a parameter, placing it in the add-on preferences panel.

Add-on preferences panelRead More »