三十五、openlayers官网示例Dynamic Data——在地图上加载动态数据形成动画效果

官网demo地址：

 Dynamic Data

 初始化地图

 const tileLayer = new TileLayer({
      source: new OSM(),
    });

    const map = new Map({
      layers: [tileLayer],
      target: "map",
      view: new View({
        center: [0, 0],
        zoom: 2,
      }),
    });

    创建了三个样式

const imageStyle = new Style({
      image: new CircleStyle({
        radius: 5,
        fill: new Fill({ color: "yellow" }),
        stroke: new Stroke({ color: "red", width: 1 }),
      }),
    });

    const headInnerImageStyle = new Style({
      image: new CircleStyle({
        radius: 2,
        fill: new Fill({ color: "blue" }),
      }),
    });

    const headOuterImageStyle = new Style({
      image: new CircleStyle({
        radius: 5,
        fill: new Fill({ color: "black" }),
      }),
    });

绘制动画效果主要还是利用了postrender事件，其原理解析可以参考这篇

十八、openlayers官网示例Custom Animation解析——地图上添加自定义动画、圆圈涟漪效果_unbykey(listenerkey);-优快云博客

// 点的数量，用于定义图形的分辨率
    const n = 200;
    // 角速度常量，用于计算当前时间的角度
    const omegaTheta = 30000;
    // 大圆的半径
    const R = 7e6;
    // 小圆的半径
    const r = 2e6;
    // 距离小圆中心的点的距离
    const p = 2e6;
    tileLayer.on("postrender", function (event) {
      //获取渲染上下文和帧状态
      //用于在地图上绘制矢量图形
      const vectorContext = getVectorContext(event);
      //包含当前帧的状态，包括时间信息
      const frameState = event.frameState;
      //计算当前角度 theta 根据当前时间和 omegaTheta 计算当前角度 theta，用于动画效果
      const theta = (2 * Math.PI * frameState.time) / omegaTheta;
      //生成外旋轮线的坐标数组
      const coordinates = [];
      let i;
      for (i = 0; i < n; ++i) {
        const t = theta + (2 * Math.PI * i) / n;
        const x = (R + r) * Math.cos(t) + p * Math.cos(((R + r) * t) / r);
        const y = (R + r) * Math.sin(t) + p * Math.sin(((R + r) * t) / r);
        coordinates.push([x, y]);
      }
      vectorContext.setStyle(imageStyle);
      //设置样式 imageStyle 并绘制多点几何（MultiPoint）
      vectorContext.drawGeometry(new MultiPoint(coordinates));
      const headPoint = new Point(coordinates[coordinates.length - 1]);
      //将头部的圆标注出来设置成不同样式
      vectorContext.setStyle(headOuterImageStyle);
      vectorContext.drawGeometry(headPoint);
      vectorContext.setStyle(headInnerImageStyle);
      vectorContext.drawGeometry(headPoint);
      //强制重新渲染地图
      map.render();
    });

完整代码：

<template>
  <div class="box">
    <h1>Dynamic Data动态数据</h1>
    <div id="map"></div>
  </div>
</template>

<script>
import Map from "ol/Map.js";
import OSM from "ol/source/OSM.js";
import TileLayer from "ol/layer/Tile.js";
import View from "ol/View.js";
import { Circle as CircleStyle, Fill, Stroke, Style } from "ol/style.js";
import { MultiPoint, Point } from "ol/geom.js";
import { getVectorContext } from "ol/render.js";
export default {
  name: "",
  components: {},
  data() {
    return {
      map: null,
    };
  },
  computed: {},
  created() {},
  mounted() {
    const tileLayer = new TileLayer({
      source: new OSM(),
    });

    const map = new Map({
      layers: [tileLayer],
      target: "map",
      view: new View({
        center: [0, 0],
        zoom: 2,
      }),
    });

    const imageStyle = new Style({
      image: new CircleStyle({
        radius: 5,
        fill: new Fill({ color: "yellow" }),
        stroke: new Stroke({ color: "red", width: 1 }),
      }),
    });

    const headInnerImageStyle = new Style({
      image: new CircleStyle({
        radius: 2,
        fill: new Fill({ color: "blue" }),
      }),
    });

    const headOuterImageStyle = new Style({
      image: new CircleStyle({
        radius: 5,
        fill: new Fill({ color: "black" }),
      }),
    });
    // 点的数量，用于定义图形的分辨率
    const n = 200;
    // 角速度常量，用于计算当前时间的角度
    const omegaTheta = 30000;
    // 大圆的半径
    const R = 7e6;
    // 小圆的半径
    const r = 2e6;
    // 距离小圆中心的点的距离
    const p = 2e6;
    tileLayer.on("postrender", function (event) {
      //获取渲染上下文和帧状态
      //用于在地图上绘制矢量图形
      const vectorContext = getVectorContext(event);
      //包含当前帧的状态，包括时间信息
      const frameState = event.frameState;
      //计算当前角度 theta 根据当前时间和 omegaTheta 计算当前角度 theta，用于动画效果
      const theta = (2 * Math.PI * frameState.time) / omegaTheta;
      //生成外旋轮线的坐标数组
      const coordinates = [];
      let i;
      for (i = 0; i < n; ++i) {
        const t = theta + (2 * Math.PI * i) / n;
        const x = (R + r) * Math.cos(t) + p * Math.cos(((R + r) * t) / r);
        const y = (R + r) * Math.sin(t) + p * Math.sin(((R + r) * t) / r);
        coordinates.push([x, y]);
      }
      vectorContext.setStyle(imageStyle);
      //设置样式 imageStyle 并绘制多点几何（MultiPoint）
      vectorContext.drawGeometry(new MultiPoint(coordinates));
      const headPoint = new Point(coordinates[coordinates.length - 1]);
      //将头部的圆标注出来设置成不同样式
      vectorContext.setStyle(headOuterImageStyle);
      vectorContext.drawGeometry(headPoint);
      vectorContext.setStyle(headInnerImageStyle);
      vectorContext.drawGeometry(headPoint);
      //强制重新渲染地图
      map.render();
    });
    map.render();
  },
  methods: {},
};
</script>

<style lang="scss" scoped>
#map {
  width: 100%;
  height: 500px;
}
.box {
  height: 100%;
}
</style>