Blender 3D and python scripting - part 025.

In this tutorial I will show a simple python script for add a String interface to the Group Output.

You can see in the next image the result of this script.

You need to have an modifier Geometry Nodes or add new one.

This is the source script with comments for each step I used:

import bpy

#get active object - default 
obj = bpy.context.active_object

# set the default start for working with Geometry Nodes modifier
# you need to have a Geometry Nodes modifier
node_group = obj.modifiers['GeometryNodes'].node_group
nodes = node_group.nodes

#get the node named 'Group Output'
geom_out = nodes.get('Group Output')

#create a string node 
string_node = nodes.new('FunctionNodeInputString')
# set the name to 'String'
string_out = string_node.outputs['String']
# set the value to "This is a string"
string_node.string = "This is a string"

# link to the Group Output
node_group.links.new(string_out, geom_out.inputs[-1])

Python : Install python with winget.

The winget command line tool enables users to discover, install, upgrade, remove and configure applications on Windows 10 and Windows 11 computers. This tool is the client interface to the Windows Package Manager service.

The winget can be installed on Windows 11 from the Windows Store.

More about winget command can be read on the Microsoft website.

After installation you can use the PowerShell command shell to install the python with this command:

winget install --id Python.Python.3 -e --source winget
Found Python 3 [Python.Python.3] Version 3.10.6
This application is licensed to you by its owner.
Microsoft is not responsible for, nor does it grant any licenses to, third-party packages.
Downloading https://www.python.org/ftp/python/3.10.6/python-3.10.6-amd64.exe
  ██████████████████████████████  27.5 MB / 27.5 MB
Successfully verified installer hash
Starting package install...
Successfully installed

Wednesday, August 10, 2022

Python 3.10.7 : Manim python package - part 001.

Manim is an engine for precise programmatic animations, designed for creating explanatory math videos, see the official GitHub repo.

Let's install this python package.

python.exe -m pip install manim
...
Successfully installed Pillow-9.2.0 Pygments-2.12.0 certifi-2022.6.15 charset-no
rmalizer-2.1.0 click-8.1.3 click-default-group-1.2.2 cloup-0.13.1 colour-0.1.5 c
ommonmark-0.9.1 decorator-5.1.1 glcontext-2.3.6 idna-3.3 isosurfaces-0.1.0 manim
-0.16.0.post0 manimpango-0.4.1 mapbox-earcut-0.12.11 moderngl-5.6.4 moderngl-win
dow-2.4.1 multipledispatch-0.6.0 networkx-2.8.5 pycairo-1.21.0 pydub-0.25.1 pygl
et-1.5.26 pyrr-0.10.3 requests-2.28.1 rich-12.5.1 scipy-1.9.0 screeninfo-0.8 ski
a-pathops-0.7.2 srt-3.5.2 tqdm-4.64.0 urllib3-1.26.11 watchdog-2.1.9 

You need to install the ffmepg software and add this to the environment path.

The default source code for create a circle is this:

from manim import *

# a simple python class
class DefaultClassExample(Scene):
    def construct(self):
        # add a circle 
        circle = Circle()
        # create a animation 
        self.play(Create(circle))

Use this command to create a video with this source code

manim -pql manim_001.py test
Manim Community v0.16.0.post0
...
INFO     Previewed File at: 'C:\Python310\media\videos\manim_001\480p15\DefaultClassExample.mp4'
...

This is the result of this command:

Blender 3D and python scripting - part 024.

In this tutorial I will show you how to use GeometryNodes with python script and Blender A.P.I.

You can see the result in the next image.

The Object Info node gets information from objects. This can be useful to control parameters in the geometry node tree with an external object, either directly by using its geometry, or via its transformation properties. An Object Info node can be added quickly by dragging an object into the node editor.

Another information can be found on the manual link.

In the next script you can see I created a simple BezierCurve object.

The definition named new_GeometryNodes_group is used to create two nodes GroupInit and GroupOutput.

I commente the source code to see some steps.

# import python packages
import bpy
from mathutils import Vector

# create a simpple BezierCurve and rename it with 'BezierCurveGeormetryNode'
bpy.ops.curve.primitive_bezier_curve_add()
bpy.ops.object.modifier_add(type='NODES')  

curve = bpy.context.active_object
curve.name = 'BezierCurveGeormetryNode'

# define a function for GroupInit and GroupOutput
def new_GeometryNodes_group():
    ''' Create a new empty node group that can be used
        in a GeometryNodes modifier.
    '''
    node_group = bpy.data.node_groups.new('GeometryNodes', 'GeometryNodeTree')
    inNode = node_group.nodes.new('NodeGroupInput')
    inNode.outputs.new('NodeSocketGeometry', 'Geometry')
    outNode = node_group.nodes.new('NodeGroupOutput')
    outNode.inputs.new('NodeSocketGeometry', 'Geometry')
    node_group.links.new(inNode.outputs['Geometry'], outNode.inputs['Geometry'])
    # the -3.5 is value for how far will be set the GroupInit and GroupOutput in the area of GeormetryNodes
    inNode.location = Vector((-3.5*inNode.width, 0))
    outNode.location = Vector((3.5*outNode.width, 0))
    return node_group

# the default curve modifier has no node group set, you need to set :
if curve.modifiers[-1].node_group:
    node_group = curve.modifiers[-1].node_group    
else:
    node_group = new_GeometryNodes_group()
    curve.modifiers[-1].node_group = node_group

# set default grup node as nodes
nodes = node_group.nodes

# get both nodes for each one 
group_in = nodes.get('Group Input')
group_out = nodes.get('Group Output')

# add the GeometryNodeObjectInfo to the GeometryNode area 
new_node_obj = nodes.new('GeometryNodeObjectInfo')
new_node_obj.inputs[0].default_value = bpy.data.objects["BezierCurveGeormetryNode"]

Monday, August 8, 2022

Python 3.10.4 : EbookLib python library - part 001.

EbookLib is a Python library for managing EPUB2/EPUB3 files. It’s capable of reading and writing EPUB files programmatically.

You can read more about this python library on this website.

First, I install with the pip tool:

C:\Python310>python -m pip install --upgrade pip
Requirement already satisfied: pip in c:\python310\lib\site-packages (22.1)
Collecting pip
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, stat
us=None)) after connection broken by 'NewConnectionError(': Failed to establish a n
ew connection: [Errno 11001] getaddrinfo failed')': /packages/1f/2c/d9626f045e7b
49a6225c6b09257861f24da78f4e5f23af2ddbdf852c99b8/pip-22.2.2-py3-none-any.whl
  Downloading pip-22.2.2-py3-none-any.whl (2.0 MB)
     ---------------------------------------- 2.0/2.0 MB 1.5 MB/s eta 0:00:00
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 22.1
    Uninstalling pip-22.1:
      Successfully uninstalled pip-22.1
Successfully installed pip-22.2.2

C:\Python310>python -m pip install lxml-4.9.0-cp310-cp310-win_amd64.whl
Processing c:\python310\lxml-4.9.0-cp310-cp310-win_amd64.whl
Installing collected packages: lxml
Successfully installed lxml-4.9.0

C:\Python310>python -m pip install EbookLib --user
Collecting EbookLib
  Using cached EbookLib-0.17.1.tar.gz (111 kB)
  Preparing metadata (setup.py) ... done
Requirement already satisfied: lxml in c:\python310\lib\site-packages (from Eboo
kLib) (4.9.0)
Collecting six
  Using cached six-1.16.0-py2.py3-none-any.whl (11 kB)
Using legacy 'setup.py install' for EbookLib, since package 'wheel' is not insta
lled.
Installing collected packages: six, EbookLib
  Running setup.py install for EbookLib ... done
Successfully installed EbookLib-0.17.1 six-1.16.0

I used a the simple python script from the last tutorial to test it:

The last tutorial used the default script from the official webpage.

Compared to the default script, I made changes, the selection in the Romanian language and diacritics...

from ebooklib import epub

book = epub.EpubBook()

# set metadata
book.set_identifier('__1976')
book.set_title('')
book.set_language('en')

book.add_author('Autho: Cătălin George Feștilă')

# create chapter
cap001 = epub.EpubHtml(title='Intro', file_name='capitolul_01.xhtml', lang='ro')
cap001.content=u'<h1>Introducere</h1><p>Această carte este...</p>'

# add chapter
book.add_item(cap001)

# define Table Of Contents
book.toc = (epub.Link('capitolul_01.xhtml', 'Introducere', 'introducere'),
             (epub.Section('O carte simplă'),
             (cap001, ))
            )

# add default NCX and Nav file
book.add_item(epub.EpubNcx())
book.add_item(epub.EpubNav())

# define CSS style
style = 'BODY {color: white;}'
nav_css = epub.EpubItem(uid="style_nav", file_name="style/nav.css", media_type="text/css", content=style)

# add CSS file
book.add_item(nav_css)

# basic spine
book.spine = ['nav', cap001]

# write to the file
epub.write_epub('ro_lan_test.epub', book, {})

This is the result of the epub file: