Unit 7.1 - CLI

Exercise 7.1.1: Build a command line interface with clap

Write a command line interface to for the prepared "gumpiball" project. It can run a simulation of moving 2d balls confined in a box (the balls dont interact with each other). It either animates the simulation in a window or saves the trajectories of balls to a svg file:

Use clap to add a command line interface to src/main.rs.

The interface should be able to do the following:

• Show the usage:

  gumpiball --help
  

  You will get this for free when using clap,

• Run an animation with n (default: 20) balls in a window with dimensions <width> x <height> (defaults: 400.0 and 400.0):

  gumpiball ui [-n <n>] [--width <width>] [--height <height>] [--paused]
  

  For parsed width, height, n, paused (boolean flag if omitted defaults to false), this corresponds to

  let animation = crate::animation::Animation::new(width, height, n);
  crate::ui::run(animation, paused)?;
  

• Load an animation setup from a json file, run it in memory and save the trajectory to a svg file:

  gumpiball trace -o <out> <config> [--dt <timestep>] [-n <n_snapshots>]
  

  For parsed out and config (json file), dt, n, this corresponds to

  let animation =
      crate::animation::Animation::load_from_json(&std::path::PathBuf::from(config))?;
  let trajectory = crate::animation::Trajectory::track(animation, 0.,
  n as f64 * dt, dt);
  crate::graphics::svg::save_to_svg(&trajectory, &std::path::PathBuf::from(out))?;