Python in CG Production

VFX Reference Platform

Driven by Autodesk

• Windows: make sure to install 64bit version of Python 3

• MacOS: use Homebrew to install Python 3

IDE

An Integrated Development Environment (IDE) is an essential tool for software development. Offering numerous time-saving and productivity features, an IDE should provide the foundation for every TD's development environment.

IDEs for Python Development

• Visual Studio Code

• Sublime Text

• PyCharm

• Atom

• Eclipse + PyDev

Visual Studio Code References

• Python in Visual Studio Code

• Getting Started with Python in VS Code

What are Packages?

• A single Python file is a module

• A package is a folder containing Python files (modules) and an __init__.py file

• The __init__.py file distinguishes it as a package. Otherwise, it is just a directory containing Python files.

Popular 3rd Party Packages

• PySide2 - UI

• NumPy - Scientific Computing

• Pylint - Code Analysis

• Django - Web Framework

• Pillow - Image Manipulation

Installing Packages from PyPI use pip.

Virtual Environments

To find out where all the installed packages are located we can use the following command in an interactive session:

import site
site.getsitepackages()

Creating Virtual Environments

The venv module provides support for creating and activating a virtual environment. This is available since Python 3.3 and it is the recommended method as of Python 3.5.

python -m venv <environment name> (i.e. numpy_latest)
(macOS) source ./venv/bin/activate 
(Windows) ./venv/bin/Activate.ps1 (or ./venv/Scripts/Activate.ps1)

Standalone Qt Application (example)

import sys
from PySide2 import QtWidgets

class StandaloneWindow(QtWidgets.QWidget):

    def __init__(self):
        super(StandaloneWindow, self).__init__(parent=None)

        self.setWindowTitle("Standalone App")
        self.setMinimumSize(400, 300)

        self.close_btn = QtWidgets.QPushButton("Close", self)
        self.close_btn.clicked.connect(self.close)


if __name__ == "__main__":
    # Create the main Qt application
    app = QtWidgets.QApplication(sys.argv)

    window = StandaloneWindow()
    window.show()

    # Enter Qt main loop (start event handling)
    app.exec_()

By default the color palette for QT seems outdated, but can be changed fairly easily to a modern dark theme using the QPalette Class. Here we are mostly interested in the ColorRole. But first we need to define the style we want to use, in my case I picked "fusion".

app.setStyle(QtWidgets.QStyleFactory.create("fusion"))

dark_palette = QtGui.QPalette()
dark_palette.setColor(QtGui.QPalette.Window, QtGui.QColor(45, 45, 45))
dark_palette.setColor(QtGui.QPalette.WindowText, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.Base, QtGui.QColor(25, 25, 25))
dark_palette.setColor(QtGui.QPalette.AlternateBase, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.ToolTipBase, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.ToolTipBase, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.Text, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.Button, QtGui.QColor(45, 45, 48))
dark_palette.setColor(QtGui.QPalette.ButtonText, QtGui.QColor(208, 208, 208))
dark_palette.setColor(QtGui.QPalette.BrightText, QtCore.Qt.red)
dark_palette.setColor(QtGui.QPalette.Link, QtGui.QColor(42, 130, 218))
dark_palette.setColor(QtGui.QPalette.Highlight, QtGui.QColor(42, 130, 218))
dark_palette.setColor(QtGui.QPalette.Highlight, QtCore.Qt.black)
app.setPalette(dark_palette)

Technically, we could go into the nitty-gritty and modify everything. All we have to do is look at the documentation for the QStyle class.

JSON (JavaScript Object Notation)

• Standardized format for storing and exchanging data, including

  • Storing configurations

  • Managing metadata (e.g. assets or shots)

  • Communicating between different applications

• Human readable and easy to understand

JSON and Python

• Python has a build-in package called json for encoding and decoding JSON

• Serialization - The process of encoding JSON

  • json.dump(data, file_name) or json.dumps(data)

• Deserialization - The process of decoding JSON

  • json.load(file_name) or json.loads(json_string)

Automation with Sockets

• Sockets are the endpoints of a two-way communication link between two programs running on the network

• A client is the socket end that requests a connection

• A server is the socket end that listens for and allows remote connections

• Both the client and server can send and receive data

Maya doesn't allow direct connections, but we can use the IP address (local host) and a given port which can be a number between 1024 and 65535.

import maya.cmds as cmds

cmds.commandPort(name="20180", sourceType="mel")
cmds.commandPort(name="20181", sourceType="python")

This can be added to the userSetup.py file in Library/Preferences/Autodesk/maya/2018/scripts/userSetup.py like so:

import maya.cmds as cmds

if not cmds.about(batch=True):
    cmds.commandPort(name="20180", sourceType="mel")
    cmds.commandPort(name="20181", sourceType="python")

The number given as name are based on the maya version e.g. 2018 and ending with a 0 for mel and a 1 for python.

BUFFER_SIZE = 4096 (usually, but can be changed)