Cesium 海量面线教程

海量面线 ·Mass Polygons & Polylines· ▶ 在线运行案例

• 案例合集：三维可视化功能案例（threehub.cn）
• 开源仓库github地址：https://github.com/z2586300277/three-cesium-examples
• 400个案例代码:网盘链接

你将学到什么

• GeometryInstance收集大量面/线几何
• 单个Primitive一次 draw 多种 instance
• PerInstanceColorAppearance/PolylineColorAppearance

效果说明

随机生成10000个三角形面 + 对应边框线，红绿交替填充，白线描边。

核心概念

合批模式

// 收集阶段
faceCollection.instances.push(new Cesium.GeometryInstance({ geometry: new Cesium.PolygonGeometry({ polygonHierarchy: new Cesium.PolygonHierarchy( Cesium.Cartesian3.fromDegreesArray(positions) ), height: 0, vertexFormat: Cesium.PerInstanceColorAppearance.VERTEX_FORMAT, }), attributes: { color: Cesium.ColorGeometryInstanceAttribute.fromColor(color), }, id: 'face' + i, }));
// 提交阶段 — 一个 Primitive 渲染全部面 viewer.scene.primitives.add(new Cesium.Primitive({ geometryInstances: faceCollection.instances, appearance: new Cesium.PerInstanceColorAppearance({ closed: true }), }));

线集合同理，用PolylineGeometry+PolylineColorAppearance。

positions 格式

本案例positions为[lon1, lat1, lon2, lat2, lon3, lat3]三角面三顶点（度）。

实现步骤

• 封装faceCollection/lineCollection带add()方法 push instance
• 循环 10000 次随机经纬生成三角
• callback 结束后各 add 一个 Primitive

• 代码要点

  import * as Cesium from 'cesium'
  const box = document.getElementById('box')
  const viewer = new Cesium.Viewer(box, {
  animation: false,//是否创建动画小器件，左下角仪表
  baseLayerPicker: false,//是否显示图层选择器，右上角图层选择按钮
  baseLayer: Cesium.ImageryLayer.fromProviderAsync(Cesium.ArcGisMapServerImageryProvider.fromUrl('https://server.arcgisonline.com/arcgis/rest/services/World_Imagery/MapServer')),
  fullscreenButton: false,//是否显示全屏按钮，右下角全屏选择按钮
  timeline: false,//是否显示时间轴
  infoBox: false,//是否显示信息框
  })
  setFaceCollection(viewer, (faceCollection, lineCollection) => {
  for (var i = 0; i < 10000; i++) {
  var longitude = Math.random() * 360 - 180;
  var latitude = Math.random() * 180 - 90;
  var positions = [longitude, latitude, longitude + Math.random(), latitude, longitude, latitude + Math.random()];
  faceCollection.add({ positions, color: i % 2 == 0 ? 'red' : 'green', id: 'face' + i, opacity: 1 })
  lineCollection.add({ positions, color: '#fff', id: 'line' + i, width: 1.0, opacity: 0.5 })
  }
  })
  // 创建大量面和线段 function setFaceCollection(viewer, callback) {
  const lineCollection = {
  instances: [],
  add({ positions, color = '#fff', id = '', width = 1.0, opacity = 1 }) {
  if (!positions) return
  this.instances.push(new Cesium.GeometryInstance({
  geometry: new Cesium.PolylineGeometry({
  positions: Cesium.Cartesian3.fromDegreesArray(positions),
  width: width * 3,
  vertexFormat: Cesium.PolylineColorAppearance.VERTEX_FORMAT
  }),
  attributes: {
  color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromCssColorString(color).withAlpha(opacity))
  },
  id
  }))
  }
  }
  const faceCollection = {
  instances: [],
  add({ positions, color = '#fff', id = '', opacity = 1 }) {
  if (!positions) return
  this.instances.push(new Cesium.GeometryInstance({
  geometry: new Cesium.PolygonGeometry({
  polygonHierarchy: new Cesium.PolygonHierarchy(Cesium.Cartesian3.fromDegreesArray(positions)),
  height: 0,
  vertexFormat: Cesium.PerInstanceColorAppearance.VERTEX_FORMAT
  }),
  attributes: {
  color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromCssColorString(color).withAlpha(opacity))
  },
  id
  }))
  }
  }
  if (callback) callback(faceCollection, lineCollection)
  // 增加面集合到场景中 viewer.scene.primitives.add(
  new Cesium.Primitive({
  geometryInstances: faceCollection.instances,
  appearance: new Cesium.PerInstanceColorAppearance({
  closed: true
  })
  })
  )
  // 增加线集合到场景中 viewer.scene.primitives.add(new Cesium.Primitive({
  geometryInstances: lineCollection.instances,
  appearance: new Cesium.PolylineColorAppearance()
  }))
  }

  完整源码：GitHub

  小结

  • 本文提供海量面线完整 Cesium.js 源码与在线 Demo，建议先运行案例再改 uniform/参数做二次实验
  • 更多 Cesium.js 实战案例见 three-cesium-examples 合集 与 GitHub 开源仓库