leaflet-velocity [![NPM version][npm-image]][npm-url] [![NPM Downloads][npm-downloads-image]][npm-url]

Version 2 Notice

As of version 2, leaflet-velocity is now under CSIRO's Open Source Software Licence Agreement, which is variation of the BSD / MIT License.

There are no other plans for changes to licensing, and the project will remain open source.

---

A plugin for Leaflet (v1.0.3, and v0.7.7) to create a canvas visualisation layer for direction and intensity of arbitrary velocities (e.g. wind, ocean current).

Live Demo: https://onaci.github.io/leaflet-velocity/

- Uses a modified version of WindJS for core functionality.
- Similar to wind-js-leaflet, however much more versatile (provides a generic leaflet layer, and not restricted to wind).
- Data input format is the same as output by wind-js-server, using grib2json.

!Screenshot

Example use:

``javascript
var velocityLayer = L.velocityLayer({
displayValues: true,
displayOptions: {
// label prefix
velocityType: "Global Wind",

// leaflet control position
position: "bottomleft",

// no data at cursor
emptyString: "No velocity data",

// see explanation below
angleConvention: "bearingCW",

// display cardinal direction alongside degrees
showCardinal: false,

// one of: ['ms', 'k/h', 'mph', 'kt']
speedUnit: "ms",

// direction label prefix
directionString: "Direction",

// speed label prefix
speedString: "Speed",
},
data: data, // see demo/*.json, or wind-js-server for example data service

// OPTIONAL
minVelocity: 0, // used to align color scale
maxVelocity: 10, // used to align color scale
velocityScale: 0.005, // modifier for particle animations, arbitrarily defaults to 0.005
colorScale: [], // define your own array of hex/rgb colors
onAdd: null, // callback function
onRemove: null, // callback function
opacity: 0.97, // layer opacity, default 0.97

// optional pane to add the layer, will be created if doesn't exist
// leaflet v1+ only (falls back to overlayPane for < v1)
paneName: "overlayPane",
});
`

The angle convention option refers to the convention used to express the wind direction as an angle from north direction in the control.
It can be any combination of bearing (angle toward which the flow goes) or meteo (angle from which the flow comes),
and CW (angle value increases clock-wise) or CCW (angle value increases counter clock-wise). If not given defaults to bearingCCW.

The speed unit option refers to the unit used to express the wind speed in the control.
It can be m/s for meter per second, k/h for kilometer per hour or kt for knots. If not given defaults to m/s.

Public methods

| method | params | description |
| ------------ | ---------- | --------------------------------- |
| setData | {Object} | update the layer with new data |
| setOptions | {Object} | update the layer with new options |

Build / watch

`shell
npm run watch
`

Reference

leaflet-velocity` is possible because of things like:

- L.CanvasOverlay.js
- WindJS
- earth

Example data

Data shown for the Great Barrier Reef has been derived from CSIRO's eReefs products

License

CSIRO Open Source Software Licence Agreement (variation of the BSD / MIT License)

[npm-image]: https://badge.fury.io/js/leaflet-velocity.svg
[npm-url]: https://www.npmjs.com/package/leaflet-velocity
[npm-downloads-image]: https://img.shields.io/npm/dt/leaflet-velocity.svg