multilinestring.go

package geom

import (
	"math"

	polyclip "github.com/ctessum/polyclip-go"
)

// MultiLineString is a holder for multiple related LineStrings.
type MultiLineString []LineString

// Bounds gives the rectangular extents of the MultiLineString.
func (ml MultiLineString) Bounds() *Bounds {
	b := NewBounds()
	for _, l := range ml {
		b.Extend(l.Bounds())
	}
	return b
}

// Length calculates the combined length of the linestrings in ml.
func (ml MultiLineString) Length() float64 {
	length := 0.
	for _, l := range ml {
		length += l.Length()
	}
	return length
}

// Within calculates whether ml is completely within p or on its edge.
func (ml MultiLineString) Within(p Polygonal) WithinStatus {
	for _, l := range ml {
		if l.Within(p) == Outside {
			return Outside
		}
	}
	return Inside
}

// Distance calculates the shortest distance from p to the MultiLineString.
func (ml MultiLineString) Distance(p Point) float64 {
	d := math.Inf(1)
	for _, l := range ml {
		lDist := l.Distance(p)
		d = math.Min(d, lDist)
	}
	return d
}

// Clip returns the part of the receiver that falls within the given polygon.
func (ml MultiLineString) Clip(p Polygonal) Linear {
	pTemp := make(Polygon, len(ml))
	for i, l := range ml {
		pTemp[i] = Path(l)
	}
	pTemp = pTemp.op(p, polyclip.CLIPLINE)
	o := make(MultiLineString, len(pTemp))
	for i, pp := range pTemp {
		o[i] = LineString(pp[0 : len(pp)-1])
	}
	return o
}

// Len returns the number of points in the receiver.
func (ml MultiLineString) Len() int {
	var i int
	for _, l := range ml {
		i += len(l)
	}
	return i
}

// Points returns an iterator for the points in the receiver.
func (ml MultiLineString) Points() func() Point {
	var i, j int
	return func() Point {
		if i == len(ml[j]) {
			j++
			i = 0
		}
		i++
		return ml[j][i-1]
	}
}