Variables

Variables in Lichtblick allow users to define global values that can be reused across multiple panels within a layout. This feature simplifies updates and ensures consistency throughout your workspace. Variables can store primitive data types such as strings, numbers, or booleans. They can also be structured as arrays (e.g., ["x", 2, false]) or maps (e.g., { "x": 2, "y": false }).

To manage variables, access the Variables tab in the sidebar, where you can view, add, and modify them.

Variables in sidebar

Using Variables

Variables are referenced using the $ prefix. For example, a variable named my_global_var is accessed as $my_global_var.

In Message Paths

Panels that support message path syntax—such as Raw Messages, Indicator, Plot, and State Transitions—can leverage variables to dynamically filter or slice data. This enables flexible and interactive data visualization.

Variables in message path

Example Workflow:

  1. Create a variable named my_ID in the Variables tab and set its value to 101.
  2. In a Raw Messages panel, use the path /my_objects.objects[:]{id==$my_ID} to inspect the object with id == 101.
  3. In a Plot panel, add /my_objects.objects[:]{id==$my_ID}.velocity as the y-axis value to plot the velocity of the selected object.

In User Scripts

User scripts can reference variables but cannot modify them. When a script is executed, it receives all variables as an object, allowing for dynamic data processing.

Accessing and Modifying Variables in Extensions

Custom extension panels can interact with variables in two ways:

  1. Accessing Variables:
    Extensions can access variables using the extension API RenderState. This allows panels to seamlessly integrate with user-defined values, enabling dynamic and context-aware visualizations.

  2. Modifying Variables:
    Extensions can also create and modify variables programmatically using the extension API PanelExtensionContext. This capability is useful for updating variables based on user interactions or data processing within the extension.

For example, a custom panel could update a variable to reflect the current state of a simulation or user input, ensuring that the layout remains responsive and interactive.

Updating Variables

Variables can be updated in two ways:

  1. Manually: Edit variable values directly in the Variables tab.
  2. Dynamically: Use interactive elements in the 3D panel or Variable Slider panel to adjust variable values in real time.

Keyboard Shortcuts

  • Press ] to toggle the visibility of the right sidebar.
  • Use input + ↑ to increment numeric variable values.
  • Use input + ↓ to decrement numeric variable values.

By utilizing variables, you can create dynamic and interactive layouts in Lichtblick, streamlining your workflow and enhancing data analysis capabilities.