golang几何计算

import "math"

func distance(x1, y1, x2, y2 float64) float64 {
    return math.Sqrt(math.Pow(x2-x1, 2) + math.Pow(y2-y1, 2))
}

type Point struct {
    X, Y float64
}

type Line struct {
    P1, P2 Point
}

func (l *Line) Length() float64 {
    return distance(l.P1.X, l.P1.Y, l.P2.X, l.P2.Y)
}

import "math"

type Circle struct {
    Center Point
    Radius float64
}

func (c *Circle) Circumference() float64 {
    return 2 * math.Pi * c.Radius
}

func (c *Circle) Area() float64 {
    return math.Pi * math.Pow(c.Radius, 2)
}

type Rectangle struct {
    P1, P2 Point
}

func (r *Rectangle) Area() float64 {
    return (r.P2.X-r.P1.X)*(r.P2.Y-r.P1.Y)
}

func (r *Rectangle) Perimeter() float64 {
    return 2*(r.P2.X-r.P1.X+r.P2.Y-r.P1.Y)
}

import "gonum.org/v1/geom"

type Polygon struct {
    Points []Point
}

func (p *Polygon) Area() float64 {
    var g geom.Polygon
    for _, pt := range p.Points {
        g = append(g, geom.Coord{X: pt.X, Y: pt.Y})
    }
    return g.Area()
}

func (p *Polygon) Perimeter() float64 {
    var g geom.Polygon
    for _, pt := range p.Points {
        g = append(g, geom.Coord{X: pt.X, Y: pt.Y})
    }
    return g.Perimeter()
}

type Triangle struct {
    P1, P2, P3 Point
}

func (t *Triangle) Area() float64 {
    a := distance(t.P1.X, t.P1.Y, t.P2.X, t.P2.Y)
    b := distance(t.P2.X, t.P2.Y, t.P3.X, t.P3.Y)
    c := distance(t.P3.X, t.P3.Y, t.P1.X, t.P1.Y)
    s := (a + b + c) / 2
    return math.Sqrt(s * (s - a) * (s - b) * (s - c))
}

func (t *Triangle) Perimeter() float64 {
    return distance(t.P1.X, t.P1.Y, t.P2.X, t.P2.Y) + distance(t.P2.X, t.P2.Y, t.P3.X, t.P3.Y) + distance(t.P3.X, t.P3.Y, t.P1.X, t.P1.Y)
}