Deck.GL ScatterplotLayer 不渲染点

Question

我一直在为这个问题挠头太久了。我有一个最简单的 React App，它将一些数据作为 props 传递给 WhatMap（之所以这么叫是因为我一直在尝试许多不同的地图库）。

但是，当我尝试使用 ScatterplotLayer 在 Deck.GL 上绘制数据点时，我在渲染的地图上根本看不到它们。

根据 React Developer Tools，ScatterplotLayer 组件确实收到了我的数据点。

我希望在柏林火车轨道的特定部分看到一些标记。

import React, { Component } from 'react';
import Header from './Header';
import WhateverMap from './Map';
import Table from './Table';

class App extends Component {
  state = {
    // Trip along the Ringbahn
    data: [
        {'timestamp': Date.now()-10000, 'coordinates': [52.536131,13.447444], 'temperature': 19},
        {'timestamp': Date.now()-9000, 'coordinates': [52.538221,13.44376], 'temperature': 20},
        {'timestamp': Date.now()-8000, 'coordinates': [52.540247,13.43899], 'temperature': 21},
        {'timestamp': Date.now()-7000, 'coordinates': [52.541751,13.43513], 'temperature': 22},
        {'timestamp': Date.now()-6000, 'coordinates': [52.54264,13.433692], 'temperature': 23},
        {'timestamp': Date.now()-5000, 'coordinates': [52.543007,13.431339], 'temperature': 24},
        {'timestamp': Date.now()-4000, 'coordinates': [52.543755,13.428731], 'temperature': 25},
        {'timestamp': Date.now()-3000, 'coordinates': [52.544295,13.427207], 'temperature': 27}
    ]
  };
  render() {
    return (
      <div className="container">
        <Header />
        <WhateverMap data={this.state.data} />
        <Table data={this.state.data} />
      </div>
    );
  }
}

export default App;

任意地图：

import React, { PureComponent } from 'react';
import MapGL from 'react-map-gl';
import DeckGL, { ScatterplotLayer } from 'deck.gl';

const mapbox_token = ''
const mapConfig = {
  center: [52.540875, 13.438545],
  zoom: 13
};

class WhateverMap extends PureComponent {
  constructor(props) {
    super(props);

    this.state = {
      viewport: {
        width: 960,
        height: 600,
        latitude: mapConfig.center[0],
        longitude: mapConfig.center[1],
        zoom: mapConfig.zoom,
        startDragLngLat: mapConfig.center,
      },
    };

    this.onChangeViewport = this.onChangeViewport.bind(this);
  }

  onChangeViewport(viewport) {
    this.setState({
      viewport: { ...this.state.viewport, ...viewport }
    });
  }

  initialize(gl) {
    gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE, gl.ONE_MINUS_DST_ALPHA, gl.ONE);
    gl.blendEquation(gl.FUNC_ADD);
  }

  render() {
    const { viewport } = this.state;
    const { data } = this.props;

    const plot_position_layer = new ScatterplotLayer({
        id: 'scatterplot-layer',
        data,
        pickable: true,
        opacity: 0.8,
        radiusScale: 6,
        radiusMinPixels: 1,
        radiusMaxPixels: 100,
        getPosition: d => d.coordinates,
    })

    return (
      <div className="reactmapgldeckgl">
        <MapGL
          {...viewport}
          mapboxApiAccessToken={mapbox_token}
          mapStyle="mapbox://styles/mapbox/dark-v9"
          onChangeViewport={this.onChangeViewport}
        >
          <DeckGL
            {...viewport}
            onWebGLInitialized={this.initialize}
            layers={[plot_position_layer]}
          />
        </MapGL>
      </div>
    );
  }
}

export default WhateverMap;

Answer 1

首先，答案。您的代码似乎是正确的，但是，一些调整似乎可以解决该错误。

const plot_position_layer = new ScatterplotLayer({
  id: 'scatterplot-layer',
  data,
  pickable: true,
  opacity: 0.8,
  radiusScale: 30,  // make the dots visible or darker background
  radiusMinPixels: 15, // make the dots visible or darker background
  radiusMaxPixels: 100,

  getPosition: d => [d.coordinates[1], d.coordinates[0]], // -> Essential Change here

  getColor: d => [255, 255, 255], // make the dots visible or darker background
})

现在，本质上发生了变化的是getPosition: d => [d.coordinates[1], d.coordinates[0]]

奇怪的是，getPosition 函数应该返回一个数组，其中第一个元素是经度而不是纬度，这就是点超出范围的原因。

看看他们在第 11 行的示例 here。

// Source data CSV
const DATA_URL =
  'https://raw.githubusercontent.com/uber-common/deck.gl-data/master/examples/scatterplot/manhattan.json'; // eslint-disable-line

export const INITIAL_VIEW_STATE = {
  longitude: -74, //remember, longitude starts with 74
  latitude: 40.7,
  zoom: 11,
  maxZoom: 16,
  pitch: 0,
  bearing: 0
};

DATA_URL 读作

[
  [-73.986022,40.730743,2], // the first element is longitude
  [-73.984293,40.729468,1],
  [-73.987752,40.732017,1],
  [-73.986887,40.730105,2],
  ...
]

希望对你有帮助