Using global plugins

In mc_rtc, every interface uses the mc_control::MCGlobalController class to initialize and run the controllers in the framework. In particular, they will run the mc_control::MCGlobalController::run() function on every iteration.

The plugin system allows one to write a component that will run at the start and/or end of this run function.

These plugins can be used for a variety of purpose:

  • Publish data using a 3rd-party middleware (for example, the ROS plugin);
  • Provide sensor data that is obtained with a different interface than the one where mc_rtc is running;
  • Provide high-level functionalities that are above a single controller scope;

The new plugin tutorial provides more information on writing plugins for mc_rtc.

The plugins’ documentation should provide information about available options and usage. This tutorial is focused on enabling and configuring these plugins.

Enabling plugins at the global level

Plugins can be added to the Plugins list in mc_rtc configuration. For example:

Plugins: [Joystick, OculusVR]

The plugins listed in this configuration are enabled regardless of the controller that is selected.

When installing a plugin, an option can be provided to enable automatic loading. Such plugins are loaded regarldess of their presence in the `Plugins` entry.

Configuration locations considered in this case

The following two files will be read by mc_rtc (if they exist):

  1. ${PLUGIN_RUNTIME_INSTALL_PREFIX}/etc/${PLUGIN_NAME}.yaml
  2. Linux/macOS: $HOME/.config/mc_rtc/plugins/${PLUGIN_NAME}.yaml
    Windows: %APPDATA%/mc_rtc/plugins/${PLUGIN_NAME}.yaml

Where ${PLUGIN_RUNTIME_INSTALL_PREFIX} is ${INSTALL_PREFIX}/lib/mc_plugins on Linux/macOS and ${INSTALL_PREFIX}/bin/mc_plugins on Windows.

Enabling plugins at the controller level

Plugins can be enabled for a given controller by adding a Plugins entry in the controller’s configuration.

Configuration locations considered in this case

Those files are only considered for the plugin configuration if the plugin is enabled at the controller level.

In addition to the global configuration files, the following files are also considered for the plugin configuration when it is enabled by a controller (if they exist):

  1. ${CONTROLLER_RUNTIME_INSTALL_PREFIX}/etc/${CONTROLLER_NAME}/plugins/${PLUGIN_NAME}.yaml
  2. Linux/macOS: $HOME/.config/mc_rtc/controllers/${CONTROLLER_NAME}/plugins/${PLUGIN_NAME}.yaml
    Windows: %APPDATA%/mc_rtc/controllers/${CONTROLLER_NAME}/plugins/${PLUGIN_NAME}.yaml

Where ${CONTROLLER_RUNTIME_INSTALL_PREFIX} is ${INSTALL_PREFIX}/lib/mc_controllers on Linux/macOS and ${INSTALL_PREFIX}/bin/mc_controllers on Windows.

When multiple controllers are enabled, if they use the same plugin then all these files are loaded together in the order the controllers appear in mc_rtc `Enabled` configuration entry.
Next tutorial: Schema structures integrated to the framework