Plotting tool

[chapulina]

Gazebo-classic has a featureful plotting tool so users can visualize various types of data coming from simulation.

We initially ported that tool to Ignition back in ign-gui0, when we were still using QWidgets. Since we moved to QML, we need a new plotting tool using QML's QtCharts.

User stories

Here are some user stories ordered from the most important to the least important. The users are defined as follows:

• ign-gui user: someone running an application built on top of Ignition GUI which they didn’t necessarily write themselves
• ign-gazebo user: someone running a simulation which they didn’t necessarily write themselves. All ign-gazebo users are ign-gui users.
• ign-gui developer: someone writing new ign-gui plugins
• ign-gazebo developer: someone writing new ign-gazebo plugins. Some ign-gazebo developers are also ign-gui developers (if they write ign-gazebo GUI plugins).

Some stories:

1. As an ign-gazebo user, I want to plot the X position of my robot over sim time
2. As an ign-gazebo user, I want to plot the acceleration data of my robot's IMU
3. As an ign-gazebo user, I want to plot the angular velocities of all my robot’s wheels on the same plot
   1. I want to add new variables to an existing plot
   2. I want to remove variables from an existing plot
4. As an ign-gazebo user, I want to different plots side-by-side
5. As an ign-gazebo user, I want to be able to zoom into a plot
6. As an ign-gui developer, I want to plot the value of an Ignition Transport topic over time
7. As an ign-gazebo user, I want to plot the value of a built-in component over time
8. As an ign-gazebo developer, I want to plot the value of a custom component over time
9. As an ign-gui user, I want to hover over a plot and see the exact value at that point
10. As an ign-gui user, I want to clear the current values in a plot
11. As an ign-gui user, I want to export a plot as a CSV file to process it with a different application
12. As an ign-gui user, I want to export a plot as a SVG file to display it on a presentation

Features

Based on the user stories above, here's a list of features to be implemented:

Ignition GUI

These features should be implemented on Ignition GUI, so they can be used by users that are not using Ignition Gazebo.

• Plot messages and fields from ign-transport topics
  • User stories: 2, 6
• List all topics and their “plottable” fields Transport Topics Plugin #69
  • User stories: 3
• Add new variables to a plot, choosing from list
  • User stories: 3
• Remove variables from a plot
  • User stories: 3
• Multiple plot plugins can be instantiated at the same time
  • User stories: 4
• Zoom
  • User stories: 5
• Hover line and value
  • User stories: 9
• Clear plot
  • User stories: 10
• Export to CSV
  • User stories: 11
• Export to SVG
  • User stories: 12

Ignition Gazebo

Additional features that are only needed in Ignition Gazebo.

Keeping track of them here just to have it all in one place.

• List all components and their “plottable” fields (leverage Component Inspector)
  • User stories: 1, 3, 7, 8
• Plot ign-gazebo components
  • User stories: 1, 3, 7, 8

Implementation

@AmrElsersy has started implementation at https://github.com/AmrElsersy/Ignition-plotting. That will be refactored and moved to ign-gazebo / ign-gui.

The current plan is to split the implementation into a few parts:

• Ignition GUI
  • • TopicViewer: An ign-gui plugin which lists all ign-transport topics currently published. Transport Topics Plugin #69
      • It's the same idea as ign-gui0's TopicViewer, see this PR:
        
      • It's a regular ign-gui plugin.
  • • PlottingInterface: A QML component that displays plots and provides an API to be updated.
      • It's installed with ign-gui and is not a plugin by itself, similar to IgnSpinBox, but including some C++ logic.
      • Most features should be here, like all the interactions (zoom, hover...), exporting to CSV, etc.
      • This is currently PlottingInterface on @claireyywang 's branch.
  • • TopicPlotting: An ign-gui plugin which plots ign-transport topics.
      • It uses PlottingInterface
      • It accepts topics being dropped from TransportTopics.
      • It's a regular ign-gui plugin.
      • This is currently TopicPlotting on @claireyywang 's branch.
• Ignition Gazebo
  • • The ComponentInspector needs to be updated so plottable values can be dragged.
  • • PlottingTool: An ign-gui plugin which plots ign-gazebo components.
      • It uses PlottingInterface
      • It accepts components being dropped from ComponentInspector.
      • It's an ign-gazebo GUI plugin (has access to components).
      • This is currently PlottingTool on @claireyywang 's branch.

[AmrElsersy]

Happy to work on that issue :D