util_test.go

package smartclip

import (
	"github.com/paulmach/orb"
)

var flips = []string{
	"reg",
	"flip over y",
	"flip over x",
	"flip over xy",
}

func m(i int) (xm, ym float64) {
	xm, ym = 1.0, 1.0
	if i&0x01 == 0x01 {
		xm = -1.0
	}
	if i&0x02 == 0x02 {
		ym = -1.0
	}

	return
}

func flipBound(i int, b orb.Bound) orb.Bound {
	xm, ym := m(i)
	if xm == -1 {
		b.Min[0], b.Max[0] = -1*b.Max[0], -1*b.Min[0]
	}
	if ym == -1 {
		b.Min[1], b.Max[1] = -1*b.Max[1], -1*b.Min[1]
	}

	return b
}

func flipRing(i int, r orb.Ring) {
	xm, ym := m(i)
	for i := range r {
		r[i][0] *= xm
		r[i][1] *= ym
	}
}

func flipPolygon(i int, p orb.Polygon) {
	for _, r := range p {
		flipRing(i, r)
	}
}

func flipMultiPolygon(i int, mp orb.MultiPolygon) {
	for _, p := range mp {
		flipPolygon(i, p)
	}
}

func deepEqualRing(r1, r2 orb.Ring) bool {
	if len(r1) != len(r2) {
		return false
	}

	if r1[0] != r1[len(r1)-1] {
		return false
	}

	if r2[0] != r2[len(r2)-1] {
		return false
	}

	// find match
	start := -1
	for i, p := range r2 {
		if p == r1[0] {
			start = i
			break
		}
	}

	if start == -1 {
		return false
	}

	for i := range r1 {
		var p2 orb.Point
		if i+start >= len(r2) {
			p2 = r2[(i+start)%len(r2)+1]
		} else {
			p2 = r2[i+start]
		}
		if r1[i] != p2 {
			return false
		}
	}

	return true
}

func deepEqualPolygon(p1, p2 orb.Polygon) bool {
	if len(p1) != len(p2) {
		return false
	}

	for i := range p1 {
		if !deepEqualRing(p1[i], p2[i]) {
			return false
		}
	}

	return true
}

func deepEqualMultiPolygon(mp1, mp2 orb.MultiPolygon) bool {
	if len(mp1) != len(mp2) {
		return false
	}

	for _, p1 := range mp1 {
		found := false
		for _, p2 := range mp2 {
			if deepEqualPolygon(p1, p2) {
				found = true
				break
			}
		}

		if !found {
			return false
		}
	}

	return true
}