Develop

Avogadro can be extended from both Python and C++ interfaces.

The code is intended to be modular and extensible, so in many cases you can add features without needing to understand the entire C++ codebase.

Working on the Avogadro codebase

Do you want to fix a bug in Avogadro, or integrate a new feature directly into the main code?

In order to start contributing code, you will need to first familiarize yourself with the structure of the project and make sure you can successfully build Avogadro. See the respective pages for guides on this.

Avogadro welcomes pull requests via GitHub. For guidance on how the project is managed, the coding style, and how to go about contributing in a constructive manner, see Contribute.

Interfacing to and extending Avogadro

Script plugins

Many features in Avogadro can be extended with Python scripts, including:

• menu commands

• electrostatic models

• file format import/export

• force fields

• input generators

These scripts can be installed by drag-and-drop into the main Avogadro window or from GitHub repositories.

For more details, see the script plugin documentation.

External scripting

Avogadro supports sending messages from external scripts, through remote procedure call (RPC) JSON. This can be very helpful for rendering images of molecules, generating orbitals, etc.

For more details, see the RPC documentation.

Libraries

The Avogadro libraries are developed to support the Avogadro2 application, and provide liberally BSD-licensed, open-source reusable components for both C++ and Python. At its core it is a platform for developing molecular visualization, editing and interactive simulation applications. This is achieved using a collection of libraries, along with a plugin interface allowing the platform to be easily extended and used in a variety of environments.

Main classes

The Avogadro libraries are implemented as a set of libraries, where all classes are implemented in the Avogadro namespace, and each library uses a namespace to distinguish members of that library. Include directories are also divided up by library, resulting in classes such as Avogadro::Core::Molecule in the include file <avogadro/core/molecule.h>. Some of the main classes that are useful to get acquainted with are:

• Core::Molecule : The base molecule class, for representing molecules.

  • Core::Atom : Class representing atoms in a molecule.

  • Core::Bond : Class representing bonds in a molecule.

• Io::FileFormatManager : Convenience functions for file format wrangling.

• Io::FileFormat : Base class for all file format readers and writers.

  • Io::CjsonFormat : Chemical JSON format reader and writer.

• Rendering::Scene : Class managing the main scene graph used for rendering.

• Rendering::Drawable : Base class for drawable items in the scene.

  • Rendering::SphereGeometry : Drawable item for spheres.

  • Rendering::CylinderGeometry : Drawable item for cylinders.

• QtGui::PeriodicTableView : A periodic table widget.

• QtOpenGL::GLWidget : Provides an OpenGL widget for 3D molecule rendering.

If you wish to extend Avogadro the main base classes are:

• QtGui::ScenePlugin : Generate geometry to be rendered in the scene.

• QtGui::ToolPlugin : Base class for mouse interaction, editing, etc.

• QtGui::ExtensionPlugin : Base class for dialog/menu extensions.

Many examples of each can be found in the avogadro/qtplugins/ subdirectories.