PolygonLayer

The Polygon Layer renders filled and/or stroked polygons.

PolygonLayer is a CompositeLayer.

import DeckGL from '@deck.gl/react';
import {PolygonLayer} from '@deck.gl/layers';

function App({data, viewState}) {
  /**
   * Data format:
   * [
   *   {
   *     // Simple polygon (array of coords)
   *     contour: [[-122.4, 37.7], [-122.4, 37.8], [-122.5, 37.8], [-122.5, 37.7], [-122.4, 37.7]],
   *     zipcode: 94107,
   *     population: 26599,
   *     area: 6.11
   *   },
   *   {
   *     // Complex polygon with holes (array of rings)
   *     contour: [
   *       [[-122.4, 37.7], [-122.4, 37.8], [-122.5, 37.8], [-122.5, 37.7], [-122.4, 37.7]],
   *       [[-122.45, 37.73], [-122.47, 37.76], [-122.47, 37.71], [-122.45, 37.73]]
   *     ],
   *     zipcode: 94107,
   *     population: 26599,
   *     area: 6.11
   *   },
   *   ...
   * ]
   */
  const layer = new PolygonLayer({
    id: 'polygon-layer',
    data,
    pickable: true,
    stroked: true,
    filled: true,
    wireframe: true,
    lineWidthMinPixels: 1,
    getPolygon: d => d.contour,
    getElevation: d => d.population / d.area / 10,
    getFillColor: d => [d.population / d.area / 60, 140, 0],
    getLineColor: [80, 80, 80],
    getLineWidth: 1
  });

  return <DeckGL viewState={viewState}
    layers={[layer]}
    getTooltip={({object}) => object && `${object.zipcode}\nPopulation: ${object.population}`} />;
}

Installation

To install the dependencies from NPM:

npm install deck.gl
# or
npm install @deck.gl/core @deck.gl/layers

import {PolygonLayer} from '@deck.gl/layers';
new PolygonLayer({});

To use pre-bundled scripts:

<script src="https://unpkg.com/deck.gl@^8.0.0/dist.min.js"></script>
<!-- or -->
<script src="https://unpkg.com/@deck.gl/core@^8.0.0/dist.min.js"></script>
<script src="https://unpkg.com/@deck.gl/layers@^8.0.0/dist.min.js"></script>

new deck.PolygonLayer({});

Properties

Inherits from all Base Layer and CompositeLayer properties.

Render Options

filled (Boolean, optional)

• Default: true

Whether to draw a filled polygon (solid fill). Note that only the area between the outer polygon and any holes will be filled.

stroked (Boolean, optional)

• Default: true

Whether to draw an outline around the polygon (solid fill). Note that both the outer polygon as well the outlines of any holes will be drawn.

extruded (Boolean, optional)

• Default: false

Whether to extrude the polygons (based on the elevations provided by the getElevation accessor. If set to false, all polygons will be flat, this generates less geometry and is faster than simply returning 0 from getElevation.

wireframe (Boolean, optional)

• Default: false

Whether to generate a line wireframe of the hexagon. The outline will have "horizontal" lines closing the top and bottom polygons and a vertical line (a "strut") for each vertex on the polygon.

Requires the extruded prop to be true.

elevationScale (Number, optional)

• Default: 1

Elevation multiplier. The final elevation is calculated by elevationScale * getElevation(d). elevationScale is a handy property to scale all elevation without updating the data.

lineWidthUnits (String, optional)

• Default: 'meters'

The units of the line width, one of 'meters', 'common', and 'pixels'. See unit system.

lineWidthScale (Boolean, optional)

• Default: 1

The line width multiplier that multiplied to all outlines of Polygon and MultiPolygon features if the stroked attribute is true.

lineWidthMinPixels (Number, optional)

• Default: 0

The minimum line width in pixels.

lineWidthMaxPixels (Number, optional)

• Default: Number.MAX_SAFE_INTEGER

The maximum line width in pixels.

lineJointRounded (Boolean, optional)

• Default: false

Type of joint. If true, draw round joints. Otherwise draw miter joints.

lineMiterLimit (Number, optional)

• Default: 4

The maximum extent of a joint in ratio to the stroke width. Only works if lineJointRounded is false.

material (Object, optional)

• Default: true

This is an object that contains material props for lighting effect applied on extruded polygons. Check the lighting guide for configurable settings.

_normalize (Object, optional)

• Default: true

Note: This prop is experimental

If false, will skip normalizing the coordinates returned by getPolygon. Disabling normalization improves performance during data update, but makes the layer prone to error in case the data is malformed. It is only recommended when you use this layer with preprocessed static data or validation on the backend.

When normalization is disabled, polygons must be specified in the format of flat array or {positions, holeIndices}. Rings must be closed (i.e. the first and last vertices must be identical). The winding order of rings must be consistent with that defined by _windingOrder. See getPolygon below for details.

_windingOrder (String, optional)

• Default: 'CW'

Note: This prop is experimental

This prop is only effective with _normalize: false. It specifies the winding order of rings in the polygon data, one of:

• 'CW': outer-ring is clockwise, and holes are counter-clockwise
• 'CCW': outer-ring is counter-clockwise, and holes are clockwise

The proper value depends on the source of your data. Most geometry formats enforce a specific winding order. Incorrectly set winding order will cause an extruded polygon's surfaces to be flipped, affecting culling and the lighting effect.

Data Accessors

getPolygon (Function, optional)

• default: object => object.polygon

Called on each object in the data stream to retrieve its corresponding polygon.

A polygon can be one of the following formats:

• An array of points ([x, y, z]) - a.k.a. a "ring".
• An array of rings. The first ring is the exterior boundary and the successive rings are the holes. Compatible with the GeoJSON Polygon specification.
• A flat array or TypedArray of coordinates, in the shape of [x0, y0, z0, x1, y1, z1, ...], is equivalent to a single ring. By default, each coordinate is assumed to contain 3 consecutive numbers. If each coordinate contains only two numbers (x, y), set the positionFormat prop of the layer to XY.
• An object of shape {positions, holeIndices}.
  • positions (Array|TypedArray) - a flat array of coordinates. By default, each coordinate is assumed to contain 3 consecutive numbers. If each coordinate contains only two numbers (x, y), set the positionFormat prop of the layer to XY.
  • holeIndices (Array) - the starting index of each hole in the positions array. The first ring is the exterior boundary and the successive rings are the holes.

// All of the following are valid polygons
const polygons = [
  // Simple polygon (array of points)
  [[-122.4, 37.7, 0], [-122.4, 37.8, 5], [-122.5, 37.8, 10], [-122.5, 37.7, 5], [-122.4, 37.7, 0]],
  // Polygon with holes (array of rings)
  [
    [[-122.4, 37.7], [-122.4, 37.8], [-122.5, 37.8], [-122.5, 37.7], [-122.4, 37.7]],
    [[-122.45, 37.73], [-122.47, 37.76], [-122.47, 37.71], [-122.45, 37.73]]
  ],
  // Flat simple polygon
  [-122.4, 37.7, 0, -122.4, 37.8, 5, -122.5, 37.8, 10, -122.5, 37.7, 5, -122.4, 37.7, 0],
  // Flat polygon with holes
  {
    positions: [-122.4, 37.7, 0, -122.4, 37.8, 0, -122.5, 37.8, 0, -122.5, 37.7, 0, -122.4, 37.7, 0, -122.45, 37.73, 0, -122.47, 37.76, 0, -122.47, 37.71, 0, -122.45, 37.73, 0],
    holeIndices: [15]
  }
]

If the optional third component z is supplied for a position, it specifies the altitude of the vertex:

Polygons with 3D positions, courtesy of @SymbolixAU and @mdsumner

getFillColor (Function|Array, optional)

• Default: [0, 0, 0, 255]

The rgba color is in the format of [r, g, b, [a]]. Each channel is a number between 0-255 and a is 255 if not supplied.

• If an array is provided, it is used as the fill color for all polygons.
• If a function is provided, it is called on each polygon to retrieve its fill color.

getLineColor (Function|Array, optional)

• Default: [0, 0, 0, 255]

The rgba color is in the format of [r, g, b, [a]]. Each channel is a number between 0-255 and a is 255 if not supplied.

• If an array is provided, it is used as the outline color for all polygons.
• If a function is provided, it is called on each polygon to retrieve its outline color.

getLineWidth (Function|Number, optional)

• Default: 1

The width of the outline of the polygon, in units specified by lineWidthUnits (default meters). Only applies if extruded: false.

• If a number is provided, it is used as the outline width for all polygons.
• If a function is provided, it is called on each polygon to retrieve its outline width.

getElevation (Function|Number, optional)

• Default: 1000

The elevation to extrude each polygon with. If a cartographic projection mode is used, height will be interpreted as meters, otherwise will be in unit coordinates. Only applies if extruded: true.

• If a number is provided, it is used as the elevation for all polygons.
• If a function is provided, it is called on each polygon to retrieve its elevation.

Note: If 3D positions are returned by getPolygon, the extrusion returned by getElevation is added to the base altitude of each vertex.

Sub Layers

The PolygonLayer renders the following sublayers:

• fill - a SolidPolygonLayer rendering the surface of all polygons.
• stroke - a PathLayer rendering the outline of all polygons. Only rendered if stroked: true and extruded: false.

Remarks

• Polygons are always closed, i.e. there is an implicit line segment between the first and last vertices, when those vertices are not equal.
• The specification of complex polygons intentionally follows the GeoJson conventions for representing polygons with holes.
• Wireframe lines are rendered with GL.LINE and thus will always be 1 pixel wide.
• Wireframe and solid extrusions are exclusive, you'll need to create two layers with the same data if you want a combined rendering effect.

Source

modules/layers/src/polygon-layer