rect/point.go

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package rect
import "math"
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// Point is a struct defining a coordinates position on a 2D plane
type Point struct {
X, Y float64
}
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// distance calculates the distance between two points
func distance(p1, p2 Point) float64 {
return math.Sqrt(math.Pow((p1.X-p2.X), 2) + math.Pow((p1.Y-p2.Y), 2))
}
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// onLine determines if point p lies on the line formed by points rp1 and rp2
func onLine(rp1, rp2, p Point) bool {
if math.Abs(distance(rp1, p)+distance(rp2, p)-distance(rp1, rp2)) < ɛ {
minx, maxx := math.Min(rp1.X, rp2.X), math.Max(rp1.X, rp2.X)
miny, maxy := math.Min(rp1.Y, rp2.Y), math.Max(rp1.Y, rp2.Y)
if minx <= p.X && p.X <= maxx && miny <= p.Y && p.Y <= maxy {
return true
}
}
return false
}