GlobeViewport (Experimental)

The GlobeViewport class takes globe view states (latitude, longitude, and zoom), and performs projections between world and screen coordinates. It is a helper class for visualizing the earth as a 3D globe.

Usage

A GlobeViewport instance is created under the hood by a GlobeView.

import {_GlobeViewport as GlobeViewport} from '@deck.gl/core';

const viewport = new GlobeViewport({
  width: 600,
  height: 400,
  longitude: -122.45,
  latitude: 37.78,
  zoom: 12
});

viewport.project([-122.45, 37.78]);
// [300,200]

Constructor

new GlobeViewport({width, height, longitude, latitude, zoom});

Parameters:

• opts (Object) - Globe viewport options

  • width (Number) - Width of the viewport.
  • height (Number) - Height of the viewport.

  geospatial arguments:

  • latitude (Number, optional) - Latitude of the viewport center on map. Default to 0.
  • longitude (Number, optional) - Longitude of the viewport center on map. Default to 0.
  • zoom (Number, optional) - Map zoom (scale is calculated as 2^zoom). Default to 11.
  • altitude (Number, optional) - Altitude of camera, 1 unit equals to the height of the viewport. Default to 1.5.

  projection matrix arguments:

  • nearZMultiplier (Number, optional) - Scaler for the near plane, 1 unit equals to the height of the viewport. Default to 0.1.
  • farZMultiplier (Number, optional) - Scaler for the far plane, 1 unit equals to the distance from the camera to the top edge of the screen. Default to 1.

Remarks:

• width and height are forced to 1 if supplied as 0, to avoid division by zero. This is intended to reduce the burden of apps to check values before instantiating a Viewport.
• Per cartographic tradition, longitudes and latitudes are specified as degrees.

Inherits all Viewport methods.

Methods

Inherits all methods from Viewport.

project

Projects world coordinates to pixel coordinates on screen.

Parameters:

• coordinates (Array) - [longitude, latitude, altitude]. altitude is in meters and default to 0 if not supplied.
• opts (Object)
  • topLeft (Boolean, optional) - Whether projected coords are top left. Default to true.

Returns:

• [x, y] or [x, y, z] in pixels coordinates. z is pixel depth.
  • If input is [longitude, latitude]: returns [x, y].
  • If input is [longitude, latitude: altitude]: returns [x, y, z].

unproject

Unproject pixel coordinates on screen into world coordinates.

Parameters:

• pixels (Array) - [x, y, z] in pixel coordinates. Passing a z is optional.
• opts (Object)
  • topLeft (Boolean, optional) - Whether projected coords are top left. Default to true.
  • targetZ (Number, optional) - If pixel depth z is not specified in pixels, this is used as the elevation plane to unproject onto. Default 0.

Returns:

• [longitude, latitude] or [longitude, latitude, altitude] in world coordinates. altitude is in meters.
  • If input is [x, y] without specifying opts.targetZ: returns [longitude, latitude].
  • If input is [x, y] with opts.targetZ: returns [longitude, latitude, targetZ].
  • If input is [x, y, z]: returns [longitude, latitude, altitude].

Source

modules/core/src/viewports/globe-viewport.ts