isabella232 / guidance-sim

Creates Mapbox Directions API guidance simulations using Mapbox GL JS

guidance-sim

A project to simulate guidance routes using Mapbox GL JS from Mapbox Directions API responses.

Simulating a Mapbox Directions Guidance Route

var simulate = require('guidance-sim').simulate;
var configuration = require('./configuration.json');

var map = new mapboxgl.Map({
    // desired map options
});
map.on('style.load', function () {
    simulate(map, configuration);
});

Parameters

• map Object Mapbox GL map object
• config Object Configuration parameters, which include the following:

parameter	required	type	default value	notes
style	Yes	String	mapbox://styles/mapbox/streets-v8	Style ID provided by Mapbox Studio
route	Yes	Object	---	Mapbox Directions v4 or v5 API response
spacing	No	String	constant	constant assumes a constant speed throughout playback acceldecel assumes an average speed per route step
zoom	Yes	Number	17	If spacing:constant - zoom when not maneuvering If spacing:acceldecel - zoom at 30mph
pitch	Yes	Number	45	Pitch when not maneuvering
timestamp	Yes	String	00h00m00s	Route simulation playback start time
speed	Yes	String	1x	Route simulation playback speed
maneuvers	Yes	Object	---	Specifies desired buffer (miles), zoom, and pitch for each maneuver

The maneuvers configuration parameter provides the simulator alternative map parameters when approaching and exiting a maneuver. The following configuration will ease sinusoidally from a pitch of 40° to 35° and zoom of 17 to 17.5 beginning 0.10 miles away from any turns, and ease back to the default values over 0.10 miles afterwards:

{
    'zoom': 17,
    'pitch': 40,
    'maneuvers': [
        {
          "type": [
            "turn right",
            "turn left"
          ],
          "buffer": 0.10,
          "zoom": 17.5,
          "pitch": 35
        }
    ]
}

Example

npm start
# --> http://localhost:9966/

Creating a Configuration File

npm run configure

This script generates a starter configuration file for running a simulation. You will be prompted to provide inputs for parameters. Default parameters, presented in magenta text, will be automatically configured if you press `[ENTER]`` without specifying a value.

If there are errors, the script will print the first error it encountered. If there are no errors, a configuration file should be created at the specified filepath (i.e., first input provided).

Additional Notes

A maneuver array will be automatically added to your configuration file. Please see the explanation above for maneuver object specifications.

For Directions v5 API responses, maneuvers have an additional modifiers field. If a maneuver type is specified but no modifiers, it is assumed that the rule should be applied to all modifier values. The exception to this is if a modifier is specified for the same type in another maneuver object. In this scenario, the more specific configuration takes precendence.

Validating a Configuration File

npm run validate

This script validates the configuration file. You will be prompted to provide the filepath of the file you'd like to validate. The default directory is the main directory.

If there are errors, the script will print the first error it encounters. If there are no errors, the script will print the JSON-formatted configuration file contents back into the terminal.

Seeking to a Different Point in the Simulation

This function runs the Emitter.stepsTaken function from guidance-replay using the start time determined by the user in the configuration file.

var Emitter = require('guidance-replay').Emitter;
var route = require('guidance-replay').route;
var stepsTaken = require('guidance-sim').stepsTaken;

var configuration = require('./configuration.json');
var emitter = new Emitter(route(configuration.route), 1000);
var seek = 10000 // desired seek time in milliseconds

stepsTaken(emitter, seek);

Parameters

• emitter Object An event emitter object coming off the Emitter function in guidance-replay
• scrub Number Desired start time in milliseconds.

Adjusting Simulation Speed

This function clears the current interval and reinitializes a new interval using a new speed value.

var setSpeed = require('guidance-sim').setSpeed;

var map = new mapboxgl.Map({
    // desired map options
});
map.on('style.load', function () {
    var response = simulate(map, configuration);
    response.on('update', function(data) {
      var newSpeed = 500;
      response.interval = setSpeed(response, response.interval, newSpeed, data.options.frequency);
    })
});

Parameters

• response Object An EventEmitter object
• interval Number An interval ID
• speed Number The duration in milliseconds over which to ease the map to the new location
• options Object Map options from initialization; see simulate.js L62:71 for more information

Test

npm test