A simple visual node editor for Python

Ryven combines flow-based visual scripting with Python. It gives you absolute freedom for your nodes and a simple system for programming them. While there are some example node packages, you will most likely rely mostly on your own nodes.

While Ryven has a large Qt-based frontend which affects performance of flow execution, you can disable particularly expensive features, and a project made in the editor can be deployed directly on the backend (ryvencore) via RyvenConsole, which does not have a single dependency!

To get started with Ryven, these are the resources that guide you through the process (in an order that makes the most sense):

1. the quick start guide below
2. the tutorials in the docs/node_tutorials directory
3. a longer guide on the website for details

Ryven comes with some example nodes, but these are, indeed, just examples, and there's no guarantee that all of them will stay. I would like to open a repository for maintaining particularly useful (frameworks of) nodes, but I will need contributors for that.

Installation

pip install ryven

and now you can launch it by running ryven on your terminal, and ryven_console for RyvenConsole. If you want to start Ryven from a Python script, just import it and run it like this

import ryven

ryven.run_ryven(
    # args...
)

quick start

A super quick intro to Ryven.

editor usage

Open Ryven by typing ryven in your terminal (or running Ryven.py with python), and create a new project. Import some example nodes via File -> Import Example Nodes and select std/nodes.py. You should now see a long list of nodes on the left. Drag and drop them into the scene and get a feeling for how they work, everything is being executed at realtime. For instance, drag two val nodes into the scene, wire them together with a + node and display the result in a result node. Now replace one of them with a slider node generating real numbers. You can also get an interactive nodes list preview inside the scene by right-clicking. You can pan around also with the right mouse button, and zoom via ctrl + scroll. You can also create new scripts, rename and delete them.

Now let's check out the small example projects: open a new Ryven window and load one of them. Take a closer look and understand what they do.

At this point you are ready to start building your own nodes.

defining nodes

Navigate to the ~/.ryven/packages/ directory and create a new folder <your_package_name>. Inside this folder create a python file nodes.py and fill it with the following content:

from ryven.NENV import *

# your node definitions go here

export_nodes(
    # list your node classes here, as tuple
)

and now you can define your own node classes. Reference the ones you want to expose to Ryven in the export_nodes function (for example export_nodes(MyNode, ) or export_nodes(Node1, Node2, )). Let's define two basic nodes:

one which generates random numbers

from random import random

class RandNode(Node):
    """Generates scaled random float values"""
    # the docstring will be shown as tooltip in the editor

    title = 'Rand'  # the display_title is title by default
    tags = ['random', 'numbers']  # for better search
    
    init_inputs = [  # one input
        NodeInputBP(dtype=dtypes.Data(default=1))
        # the dtype will automatically provide a suitable widget
    ]
    init_outputs = [  # and one output
        NodeOutputBP()
    ]
    color = '#fcba03'

    def update_event(self, inp=-1):
        # update first output
        self.set_output_val(0, 
            random() * self.input(0)  # random float between 0 and value at input
        )

and another one which prints them

class PrintNode(Node):
    title = 'Print'
    init_inputs = [
        NodeInputBP(),
    ]
    color = '#A9D5EF'

    def update_event(self, inp=-1):
        print(self.input(0))

and that's it! Go ahead and import your nodes package in Ryven. Place both in the scene and connect the Rand node to your Print node.

You can do a lot more than shown above. A summary of the main features:

• many modifiable themes
• simple and unrestricted nodes system
• actions / right-click operations system for nodes
• variables system with update mechanism for nodes that automatically adapt to change of data
• logging support
• rendering flow images
• stylus support for adding handwritten notes / drawings on touch devices
• exec flow support like UnrealEngine BluePrints
• Qt widgets support

and some examples for those:

many modifiable themes

Also light themes!

actions / right-click operations system for nodes

which can be edited through the API at any time.

class MyNode(Node):
    ...

    def a_method(self):
        self.actions['do something'] = {
            'method': self.do_sth,
        }

    # with some method...
    def do_sth(self):
        ...

Qt widgets

You can add custom Qt widgets for your nodes. Define a widgets.py file next to your nodes.py with similar structure to nodes.py, see the guide for detailed instructions.

widgets.py

from ryven.NWENV import *
from qtpy.QtWidgets import QWidget

class SomeMainWidget(MWB, QWidget):
    def __init__(self, params):
        MWB.__init__(self, params)
        QWidget.__init__(self)
    ...

class SomeInputWidget(IWB, QWidget):
    def __init__(self, params):
        IWB.__init__(self, params)
        QWidget.__init__(self)
    ...

export_widgets(
    SomeMainWidget,
    SomeInputWidget,
)

nodes.py

class MyNode(Node):
    main_widget_class = MyNode_MainWidget
    main_widget_pos = 'below ports'  # alternatively 'between ports'

stylus support

logging support

import logging

class MyNode(Node):
    def somewhere(self):
        self.logger = self.new_logger('nice log')
    
    def update_event(self, inp=-1):
        self.logger.info('updated!')

variables system

with an update mechanism to build nodes that automatically adapt to change of data.

class MyNode(Node):
    def a_method(self):
        self.register_var_receiver('x', method=self.process)

    # with some method...
    def process(self, val_of_x):
        # processing new value of var 'x'
        ...

Contributions

Contributing guidelines: here.

Particularly effective ways to contribute outside direct development of the software include

• creating examples
• creating tutorials
• creating node packages
• improving documentation

Also notice that there's a discussions area in this repo.

The docs page on the website is made with Docsify, so you can improve it by simply editing the markdown. The whole website sources are also on GitHub.

Cheers.