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VisuAlea Manual

OpenAlea provides an high level visual programming interface visualea See : Visualea package

Launching the application

On Linux

In a shell, run the following command


On Windows

Use start→ OpenAlea → Visualea

Main Window

The main windows is composed by :

  • A- The package manager list logical components
  • B - The workspaces allows to manipulate functionalities represented as boxes with inputs and outputs.
  • C - Graphical interface of a node
  • E - The python interpreter for low level interaction with completion
  • F - Python code editor

Package Manager

The package manager find dynamically the available components on the system.

The package manager provides different tabs :

  • The package tab displays the available packages and sub packages
  • The category tab allows to sort the component in a more convenient way
  • The search tab provides a research tool. The research is done on the name, category and description for every nodes.

Package / Node / Dataflow

The package manager contains packages. A package is a distribution unit containing a set of components ( node / graphs). A package has several associated informations like :

  • Authors
  • Institutes
  • License
  • Description
  • URL

These package informations are accessible from the context menu:

  • Package Context Menu
    • Open Url : Open associated url
    • Infos : Display meta informations

Each package element has also a context menu :

  • Node (Component) Context Menu
    • Open : Open the node
    • Edit : Edit the node (Code Editor for Python node, Dataflow for Composite node)
    • Remove : Remove the node from the package

Note 1 : Tooltip are available by moving the mouse pointer on an object.

Note 2 : Double click on an object can either Open it or Edit it depending of its type.

User packages / system packages

Package Manager operations (menu)

  • → Load wralea_file : load a particular package description file
  • → Reload all packages : search all packages on the local system
  • → Find Nodes : Open the search tab
  • → Create
    • → Package : Create a new user package
    • → Python Node : Create a new component based on python code
    • → Composite Node : Create a new component based on other components (Macro node)


User can create simple process by interconnecting boxes together. A box represent a function with inputs and outputs.

Opening workspaces

You can create several workspaces :

  • Workspace → New empty workspace or CTRL + W
  • Double click on a graph in the package manager. In this case the workspace contains the graph.

Adding new nodes

  • You can add nodes by doing a drag and drop between the package manager and the workspace.
  • You also do Copy/Paste operation directly in the workspace.

A node is represented by a box with input and outputs ports.

  • Inputs are on the top of the box
  • Outputs are on the bottom of the box

You can view the documentation of a node by letting the mouse pointer on the node.

Connecting nodes

You can connect the nodes between them by doing a drag and drop operation between ports.

  • An output port can be connected to several different input ports : in this case the value will be copied to the different port
  • An input port can be connected to several different output ports : in this cas the value will be the list of the different value of the connected output ports.

Node Graphical interface

Each node has a configuration dialog (its widget). You can open the widget with the context menu (right click → open widget).

The widget depends of the node, it can be a simple value editor (spinbox for numbers, text editor…), or complex editor like 3D visualizer.

Running a dataflow

The graph of nodes form an expression.

To evaluate the expression :

  • Menu → Workspace → Run will evaluate all the graph
  • Context Menu → Run on a particular node will evaluate only the selected node and its dependencies.

If you change a value of a node, the evaluation algorithm will compute only the changed nodes and their dependencies, avoiding to do several times the same computation.

The node contained in a graph can be in different states/ The color of a node depends of its state:

  • Red : the node need to be reevaluated
  • Blue : the node doesn't need to be reevaluated

To change the status of a node or of a dataflow:

  • Context Menu → Reset: Reset the corresponding node
  • Workspace → Reset : Reset all the dataflow
  • Workspace → Invalidate : Force all nodes to be reevaluated the next time

You can visualize the value of a port : Context Menu → Print and with tooltips.

Save a dataflow / Composite Node

A Composite node is an abstraction of a dataflow graph. It is a node which contains other nodes.

Composite nodes are used to :

  • save a dataflow
  • manage complexity

Saving a dataflow

To save a dataflow :

  • Save the workspace as a composite node : Workspace → Save as composite node or CTRL + E

This function will save the graph but also the value of the node inputs

Managing complexity

A composite node can be reused as a normal node (a simple box). You can embed a part of a graph in a composite node :

  • Select the node you want to group/embed
  • Workspace → Group or CTRL +G

This will create a new node containing all selected nodes.

This function can be used to improve the readability of your graph and facilitate reuse of complex functionalities.


As normal node, a composite node has inputs and outputs. They can be set :

  • Workspace → configure I/O

Each input has :

  • a name
  • an interface (used for the graphical interface and for type checking)
  • a default value

Each ouyput has :

  • a name
  • an interface (used for type checking)

Open/Save a session

You can save the entire session in order to keep all the data you currently use.

  • File → save session : Save the current session for a furur reuse
  • File → open session : Open a previously saved session
  • File → new session : reinitialize all the workspace
This functionality is not safe and we do NOT recommand to use it. Use export as composite node instead to save your work

Export Application

A graph can be exported as a standalone application (a python module) : Workspace → Export to Application.

The application can be previewed with the command : Workspace → Preview Application.

Data Pool

The data pool is a kind of data clipboard to store temporally computed data.

  • You can send data to the Pool : Port Context menu → Send to pool
  • You can re-use data of the pool in the dataflow by doing a drag and drop from the datapool list to aaninput port.
  • You can also access to the datapool in the interpreter (drag and drop to the interpreter will copy the correct code):
datapool['name'] = object # set a data instance
print datapool['name']    # get a data instance

Python Operations

At any moment, you can use the python interpreter to launch python command or scripts.

The interpreter defines special variables :

  • session contains the different workspaces and the nodes they contain
  • datapool is the datapool dictionary
  • pmanager is the package manager

By doing a drag&drop of node with the mouse mid button, you will be able to access to the data of a node.

You can also do a drag and drop from the datapool.


Interface preferences can be set via the preference dialog : Window → Preferences

Package manager

This tab is used to set the directories to search for openalea packages.


Python editor


packages/core/visualea/manual.txt · Last modified: 2008/01/22 15:52 by admin   Back to top
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