Running From Flutter

First import the required files with:

import 'package:sail_routing_dart/route_model.dart';
import 'package:vector_math/vector_math.dart';

This will give you the data types you need.\

Calculating Routes

To calculate a route, first we need to create a route. The constructor should giv you hints but heres an example:

  Vector2 start = new Vector2(0.0, 0.0);
  Vector2 end = new Vector2(1.0, -10.2);
  double wind = 3 * pi / 2;
  RouteModel route = new RouteModel(start: start, end: end, wind_radians: wind);

The constructor will take care of the rest. To see the route it calculated, add print(route) which gives a full print-out of the route including any intermediate points the route calculation added if any. Will look something like this:

[ROUTE]
        Start: x: 0.0   y: 0.0
        End: x: 1.0     y: -10.2
        wind_radians: 4.71238898038469
        IntermediatePoints: (
                x: 0.5735762412306388   y: -0.8191521809137372, 
                x: 4.071056634450088    y: -5.814074365385329, 
                x: 1.573576241230639    y: -9.380847819086263)
[/ROUTE]

Single Tack Routing

Run the single tack implementation of the algorithm on a hard-coded route with:

dart lib/calc_route.dart -v

'v' flag is for verbose mode. The route will be displayed in lib/plotted_course.png

Polar Plot Routing

This process uses polar plots of sail boats to obtain the optimal sailing route based on a polar plot, wind speed and direction.

Polar Plot

A number of sail boats use polar plots to determine a boat's speed in respect to wind speed and direction. CSVs are used to generate a polar plot object in order to determine optimal headings. A sample CSV file is contained in the assets folder of the library and this file is sourced from here: http://jieter.github.io/orc-data/site/csvplot.html

Inside the CSV files the columns are described as follows:

twa/tws - The relative angle from the wind that the row corresponds to. 6,8,10,12,14,16,20 - Each one of these columns is labeled as a separate wind speed in knots. And the column's value represents the boat's speed a that wind speed.

For example one row in the CSV file has the first column representing its relative wind angle. The following columns represent the boat's speed with that angle and wind speed.

To construct a polar plot object use the following code:

PolarPlot plot = PolarPlot();

// Must be initialized as it is an async process
await plot.init("path/to/csvfile.csv");

This PolarPlot class can give the optimal heading given windDirection, desiredDirection and windSpeed:

double optimalHeading = plot.getOptimalHeading(idealDirection, windDirection, windSpeed);

This optimal heading is in the format of degrees and cardinal directions (0.0 is North, 90.0 is East, etc).

Polar Routing

To use the polar routing, a plot will first need to be constructed from a CSV file as described above. Then it will be given to the router's construction. Using the getTransRoute, you can obtain a list of points containing the optimal path. This implementation can only give a maximum of 3 points in the route as it does not factor in obstacles or course boundaries. Also, Currently wind at 180 degrees and zero degrees are the only consistently working values for windDirection. If you'd like to do another wind angle, you may want to transform the points based on the wind before hand.

PolarRouter pr = PolarRouter(plot);
List<List<double>> route = pr.getTransRoute(start, end, windSpeed, windDirection);

Visualization

String whoToBlame() => 'Daniel';

Dart doesn't have any good graphing package that isn't some extension or some js library like charts.js. My quick and dirty approach (because it's just for our internal use) is something that writes all the necessary info about a course to a file and a python script that reads that file and saves a graph.

So it goes Dart code --> plotter_data.json --> pretty_plotter.py --> plotted_course.png

If you're in the code, do something like this:

    RouteWriter rw = new RouteWriter();
    rw.writeToFile(
        start: [0.0, 1.0], 
        end: [1.0, 10.0], 
        points: <<A list of other intermediate points>>,
        wind_direction: 30.0);
    rw.run_python_plotter();

This should plot this course and save it in the file lib/plotted_course.png To run a test from the command line, run with dart lib/main.dart