config.yml

DouglasPeuckerEpsilon: 0.03 # epsilon for Douglas-Peucker algorithm

route.go

// DouglasPeucker simplifies a path using the Douglas-Peucker algorithm.
func DouglasPeucker(points []TenantPosition, epsilon float64) []TenantPosition {
	if len(points) <= 2 {
		return points
	}

	dMax := 0.0
	index := 0

	// Calculate the point farthest from the line segment formed by the first and last points.
	for i := 1; i < len(points)-1; i++ {
		d := perpendicularDistance(points[i], points[0], points[len(points)-1])
		if d > dMax {
			index = i
			dMax = d
		}
	}

	if dMax > epsilon {
		// Recursively simplify the two subpaths formed by the farthest point.
		firstPart := DouglasPeucker(points[:index+1], epsilon)
		secondPart := DouglasPeucker(points[index:], epsilon)
		return append(firstPart[:len(firstPart)-1], secondPart...)
	}

	return []TenantPosition{points[0], points[len(points)-1]}
}

// perpendicularDistance calculates the perpendicular distance from a point to a line segment.
func perpendicularDistance(point, start, end TenantPosition) float64 {
	if start == end {
		return math.Sqrt(math.Pow(point.XY.X-start.XY.X, 2) + math.Pow(point.XY.Y-start.XY.Y, 2))
	}

	return math.Abs((point.XY.X-start.XY.X)*(end.XY.Y-start.XY.Y)-(point.XY.Y-start.XY.Y)*(end.XY.X-start.XY.X)) /
		math.Sqrt(math.Pow(end.XY.X-start.XY.X, 2)+math.Pow(end.XY.Y-start.XY.Y, 2))
}