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多边形绘制示例

这个示例演示如何使用 DMap3D SDK 在地图上交互式绘制多边形。

效果预览​

用户左键依次点击添加顶点，右键完成绘制并自动闭合多边形，支持填充和边框样式。

完整代码​

src/components/PolygonDrawing.tsx
import { useEffect, useRef, useState } from 'react'
import * as Cesium from 'cesium'
import DMap3D from 'dmap3d'
import './PolygonDrawing.css'

function PolygonDrawing() {
  const containerRef = useRef<HTMLDivElement>(null)
  const viewerRef = useRef<Cesium.Viewer | null>(null)
  const toolRef = useRef<any>(null)
  const [isActive, setIsActive] = useState(false)

  useEffect(() => {
    if (!containerRef.current) return

    Cesium.Ion.defaultAccessToken = 'your-cesium-ion-token'

    const viewer = new Cesium.Viewer(containerRef.current, {
      animation: false,
      fullscreenButton: false,
      geocoder: false,
      homeButton: false,
      sceneModePicker: false,
      selectionIndicator: false,
      timeline: false,
      navigationHelpButton: false,
      infoBox: false,
      baseLayerPicker: false,
      terrainProvider: new Cesium.EllipsoidTerrainProvider({}),
    })
    viewerRef.current = viewer

    viewer.camera.setView({
      destination: Cesium.Cartesian3.fromDegrees(116.4074, 39.9042, 5000),
      orientation: {
        heading: Cesium.Math.toRadians(0),
        pitch: Cesium.Math.toRadians(-45),
        roll: 0,
      },
    })

    // 创建多边形绘制工具
    const tool = new DMap3D.drawing.polygon({
      viewer,
      style: {
        fillColor: '#0000FF',
        fillAlpha: 0.3,
        outlineColor: '#FFFFFF',
        outlineWidth: 2,
        outlineAlpha: 1.0,
      },
      clampToGround: true,
    })
    toolRef.current = tool

    return () => {
      tool.destroy()
      viewer.destroy()
    }
  }, [])

  const handleDraw = () => {
    const tool = toolRef.current
    if (!tool) return
    tool.draw((entity: any, positions: Cesium.Cartesian3[]) => {
      console.log('多边形绘制完成，顶点数:', positions.length)
      setIsActive(false)
    })
    setIsActive(true)
  }

  const handleStop = () => {
    toolRef.current?.deactivate()
    setIsActive(false)
  }

  const handleClear = () => {
    toolRef.current?.clear()
    if (isActive) toolRef.current?.deactivate()
    setIsActive(false)
  }

  // 从数据加载
  const handleLoadData = () => {
    const tool = toolRef.current
    if (!tool) return
    tool.loadFromData([
      [116.39, 39.90],
      [116.41, 39.90],
      [116.41, 39.92],
      [116.39, 39.92],
    ])
  }

  return (
    <div className="polygon-drawing">
      <div ref={containerRef} className="cesium-container" />

      <div className="control-panel">
        <h3>多边形绘制</h3>
        <p>左键添加顶点，右键完成（自动闭合）</p>

        <div className="buttons">
          <button onClick={handleDraw} disabled={isActive}>
            {isActive ? '绘制中...' : '开始绘制'}
          </button>
          <button onClick={handleStop} disabled={!isActive}>停止</button>
          <button onClick={handleClear}>清除</button>
        </div>

        <button className="load-btn" onClick={handleLoadData}>
          从数据加载示例多边形
        </button>
      </div>
    </div>
  )
}

export default PolygonDrawing

样式文件​

src/components/PolygonDrawing.css
.polygon-drawing {
  position: relative;
  width: 100%;
  height: 100vh;
}

.cesium-container { width: 100%; height: 100%; }

.control-panel {
  position: absolute; top: 20px; right: 20px;
  background: rgba(255, 255, 255, 0.95); padding: 20px;
  border-radius: 8px; box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  min-width: 250px;
}

.control-panel h3 { margin: 0 0 10px 0; font-size: 18px; }
.control-panel p { margin: 0 0 15px 0; color: #666; font-size: 14px; }
.buttons { display: flex; gap: 8px; margin-bottom: 15px; }
.buttons button {
  flex: 1; padding: 8px 12px; border: none; border-radius: 4px;
  background: #1890ff; color: white; cursor: pointer; font-size: 14px;
}
.buttons button:hover { background: #40a9ff; }
.buttons button:disabled { background: #d9d9d9; cursor: not-allowed; }

.load-btn {
  width: 100%; padding: 8px; border: 1px solid #1890ff; border-radius: 4px;
  background: white; color: #1890ff; cursor: pointer; font-size: 14px;
}
.load-btn:hover { background: #e6f7ff; }

关键代码说明​

1. 创建多边形绘制工具​

const tool = new DMap3D.drawing.polygon({
  viewer,
  style: {
    fillColor: '#0000FF',     // 填充颜色
    fillAlpha: 0.3,           // 填充透明度
    outlineColor: '#FFFFFF',  // 边框颜色
    outlineWidth: 2,          // 边框宽度
    outlineAlpha: 1.0,        // 边框透明度
  },
  clampToGround: true,        // 贴地
})

2. 交互绘制​

tool.draw((entity, positions) => {
  // entity: 多边形 Entity
  // positions: 顶点坐标数组
  console.log('顶点数:', positions.length)
})

左键添加顶点，右键完成绘制并自动闭合。

3. 从数据加载​

// 经纬度数组
tool.loadFromData([
  [116.39, 39.90],
  [116.41, 39.90],
  [116.41, 39.92],
  [116.39, 39.92],
])

扩展功能​

  1. 面积计算 - 自动计算多边形面积
  2. 顶点编辑 - 拖拽修改已绘制多边形的顶点
  3. 打孔 - 在多边形内部挖洞
  4. 布尔运算 - 多边形的合并、裁剪、相交

相关 API​