package ruleserver
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import (
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"math"
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)
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func min(num1 float64, num2 float64) float64 {
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if num1 < num2 {
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return num1
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}
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return num2
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}
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func max(num1 float64, num2 float64) float64 {
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if num1 < num2 {
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return num2
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}
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return num1
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}
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//Point 坐标点
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type Point struct {
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X float64 `json:"x"`
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Y float64 `json:"y"`
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}
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//Rect 检测目标
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type Rect struct {
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X float64
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Y float64
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Width float64
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Height float64
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}
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//Pointfloat 坐标点
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type Pointfloat struct {
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X float64 `json:"x"`
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Y float64 `json:"y"`
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}
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//PintIsInPolygon 判断点是否在多边形内部
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//point为要判断的坐标点
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//polygon是多边形各点数组
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func pintIsInPolygon(point Pointfloat, polygon []Point, widthScale float64, heightScale float64) bool {
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var nCross int = 0
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for i := 0; i < len(polygon); i++ {
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p1 := polygon[i]
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p2 := polygon[(i+1)%len(polygon)]
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// 根据摄像机所拍图像与前端画布的比例将区域放大
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p1.X = p1.X * widthScale
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p1.Y = p1.Y * heightScale
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p2.X = p2.X * widthScale
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p2.Y = p2.Y * heightScale
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if p1.Y == p2.Y {
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continue
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}
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if point.Y < min(p1.Y, p2.Y) {
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continue
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}
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if point.Y > max(p1.Y, p2.Y) {
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continue
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}
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X := (point.Y-p1.Y)*(p2.X-p1.X)/(p2.Y-p1.Y) + p1.X
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if X > point.X {
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nCross++
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}
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}
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return nCross%2 != 0
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}
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//GetLocation 将一个给定起始坐标，宽度长度的矩形区域均分为n方份并返回中心坐标（n为单边平分数值）和面积
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func getLocation(rect Rect, n int) ([]Pointfloat, float64) {
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xArr := make([]float64, n) // 用切片不用数组，数组不能用变量定义长度
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yArr := make([]float64, n)
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pointArr := make([]Pointfloat, 0, n*n)
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for i := 0; i < n; i++ {
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xArr[i] = rect.X + (rect.Width/float64(2*n))*float64(2*i+1)
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yArr[i] = rect.Y + (rect.Height/float64(2*n))*float64(2*i+1)
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}
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for i := 0; i < n; i++ {
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for j := 0; j < n; j++ {
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point := Pointfloat{X: xArr[i], Y: yArr[j]}
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pointArr = append(pointArr, point)
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}
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}
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s := rect.Width * rect.Height
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return pointArr, s
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}
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//ComputePolygonArea 计算任意多边形面积
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func computePolygonArea(polygon []Point) float64 {
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pointNum := len(polygon)
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var s float64 = 0
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if pointNum < 3 {
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s = 0
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}
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for i := 0; i < pointNum; i++ {
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s += polygon[i].X*polygon[(i+1)%pointNum].Y - polygon[i].Y*polygon[(i+1)%pointNum].X
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}
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area := math.Abs(s / 2)
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return area
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}
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//PgsInterPercent calculate percent of two polygon intersection 计算两个多边形的重叠占比
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func PgsInterPercent(pgpts []Point, box Rect, widthScale float64, heightScale float64) (percent float64) {
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areapts, areaBox := getLocation(box, 10)
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var count = 0
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for _, pts := range areapts {
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if pintIsInPolygon(pts, pgpts, widthScale, heightScale) {
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count++
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}
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}
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perInterBox := float64(count) / float64(len(areapts)) // 重合面积占矩形的比例
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areaInter := perInterBox * areaBox
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areaPg := computePolygonArea(pgpts)
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perInterPg := areaInter / areaPg // 重合面积占多边形区域的比例
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// 哪个占的比例大按哪个计算
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if perInterBox > perInterPg {
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return perInterBox
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}
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return perInterPg
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}
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