Python + PySide2 Node Editor

Node editor framework which can be used as a standalone application or integrated into Python + PySide2 projects.

Compatibility

• This application was created using Python 3.10.11.
• Tested with Windows 10 and OSX v10.12.

Dependencies

• PySide2==5.15.2.1
• shiboken2==5.15.2.1

To install the dependencies in your current environment you can run the following snippet:

pip install -r requirements.txt

How to use

• Start the application by running main.py (Make sure the dependencies have been installed first).

Command	Key binding
Open context menu	RMB
Focus on selected	F
Delete selected	Del
Pan scene view	MMB
Zoom in/out	Scroll up/down

• The context menu contains these actions:

How to create a custom nodes

To create your own custom node you can simply create new child class of the abstract class LogicNode and use it as a template.

In your new class need to define and declare a few things:

1. The name of the node, using the constant NAME attribute.
2. An unique id for the node, using the id variable (Preferrebly using uuid like the LogicNode class).
3. An empty list where the node can store its connections, using the connections variable. This is used for determine the node evaluation order.
4. The UI color of the node, using the node_color variable.
5. The input/output, using the io_ports variable. This variable should be a dict. The keys in the dict should be a string and the values should be an instance of the LogicPort class.
6. You also need to define a execute method which should hold the actual expression of the node and then pass that data to the output port. For example, a multiply expression node would have the execute look something like this:

output_port.data = (input1_port.data + input2_port.data)

Here is an example on how you can create your own expression node:

import uuid
from core.logic_port import LogicPort

class ExampleNode(LogicNode):

    NAME = "My Custom Node" # Name of the node displayed in the UI.

    def __int__(self):
        self.id = uuid.uuid4() # The node need an unique id for save/load functionality to work
        self.node_color = (255, 255, 255) # Color of the node displayed in the UI.
        self.connections = [] # Used in runtime to determine evaluation order of the connected nodes.

        # Declare io ports by adding a dict with name keys and instances of LogicPort as values.
        self.io_ports = {"Input" : LogicPort(is_input=True), "Output" : LogicPort(is_input=False)}

    def execute(self):
        ''' 
        This is where the node operation is done and then passed to the output port.
        '''
        output_port = self.io_ports.get("Output")
        output_port.data = (5 + 5)

To make the custom node show up in the scene in the application you need to call the create_node method of the controller class and pass the name of your node class.

controller = Controller(scene)
controller.create_node("ExampleNode")

The example nodes in the applications are created by connecting the create_node method to a context menu action. Like this:

self.controller.scene.add_contextmenu_item(partial(self.controller.create_node, "AddNode"), "Add Node")