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89 lines
3.2 KiB
TypeScript
89 lines
3.2 KiB
TypeScript
/*
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* @Author: cbwu 504-wuchengbo@htsdfp.com
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* @Date: 2024-03-22 15:42:49
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* @LastEditors: cbwu
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* @LastEditTime: 2024-04-01 14:05:43
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* @Description: 地理计算
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*/
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import { Cartesian3, Math as Cesium_Math } from 'cesium'
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/**
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* 计算空间中一点到一条直线的最短距离的交点（在不考虑地球曲率的情况下）
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* @param lineStart 直线的起点：[longitude1, latitude1, height1]
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* @param lineEnd 直线的终点:[longitude2, latitude2, height2]
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* @param point 空间中的点:[[longitude3, latitude3, height3]]
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* @returns 最近的交点
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*/
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function getClosestPoint(
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lineStart: Cartesian3,
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lineEnd: Cartesian3,
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point: Cartesian3,
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): Cartesian3 {
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// 计算直线方向向量
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const lineDirection = new Cartesian3()
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Cartesian3.subtract(lineEnd, lineStart, lineDirection)
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Cartesian3.normalize(lineDirection, lineDirection)
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// 计算点到直线起点的向量
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const pointToStart = new Cartesian3()
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Cartesian3.subtract(point, lineStart, pointToStart)
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// 计算投影长度，即点到直线的向量在直线方向向量上的分量长度
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const projectionLength = Cartesian3.dot(pointToStart, lineDirection)
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// 使用标量乘法和向量加法确定交点
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const closestPoint = new Cartesian3()
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Cartesian3.multiplyByScalar(lineDirection, projectionLength, closestPoint)
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Cartesian3.add(lineStart, closestPoint, closestPoint)
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return closestPoint
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}
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/**
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* 判断一个点是否在直线上（在不考虑地球曲率的情况下）
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* @param lineStart 直线的起点：[longitude1, latitude1, height1]
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* @param lineEnd 直线的起点：[longitude2, latitude2, height2]
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* @param pointToCheck 直线的起点：[longitude3, latitude3, height3]
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* @param tolerance 容差
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* @returns 是否在线段上
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*/
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function isOnLineSegment(
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lineStart: Cartesian3,
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lineEnd: Cartesian3,
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pointToCheck: Cartesian3,
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tolerance: number = Cesium_Math.EPSILON1,
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): boolean {
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const dist_AP = Cartesian3.distance(lineStart, pointToCheck)
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const dist_BP = Cartesian3.distance(lineEnd, pointToCheck)
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const dist_AB = Cartesian3.distance(lineStart, lineEnd)
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const isCollinear = Math.abs(dist_AP + dist_BP - dist_AB) < tolerance
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return isCollinear
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/*
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const startToEnd = new Cartesian3()
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const startToPoint = new Cartesian3()
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const endToPoint = new Cartesian3()
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// 计算向量
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Cartesian3.subtract(lineEnd, lineStart, startToEnd)
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Cartesian3.subtract(pointToCheck, lineStart, startToPoint)
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Cartesian3.subtract(pointToCheck, lineEnd, endToPoint)
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// 判断共线
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const cross = Cartesian3.cross(startToEnd, startToPoint, new Cartesian3())
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console.log('cross:' + Cartesian3.magnitude(cross).toString())
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// Math.EPSILON6 是一个非常小的值，用来防止浮点数计算的误差
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const isCollinear = Cartesian3.magnitude(cross) < tolerance
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// 判断点是否在线段之间
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let isBetween = false
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if (isCollinear) {
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const dotProduct1 = Cartesian3.dot(startToEnd, startToPoint)
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const dotProduct2 = Cartesian3.dot(startToEnd, endToPoint)
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isBetween = dotProduct1 >= 0 && dotProduct2 <= 0
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}
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return isBetween
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*/
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}
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export { getClosestPoint, isOnLineSegment }
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