/
period.go
253 lines (237 loc) · 5.8 KB
/
period.go
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package angle
//start and end angle of period,
//both are supposed to be [0;360)
//[a,a) is an empty, if not isFull
//isFull is 360 degree full circle
type Period struct {
start, end float64
isFull bool
}
var EmptyPeriod = Period{0, 0, false}
var FullPeriod = Period{0, 0, true}
func NewPeriod(start, end float64) Period {
return newPeriod(Norm(start), Norm(end))
}
func newPeriod(start, end float64) Period {
return Period{
start: start,
end: end}
}
func (a Period) Empty() bool {
return a.start == a.end && !a.isFull
}
func (a Period) IsFull() bool {
return a.isFull
}
func (a Period) Get() (start, end float64) {
return a.start, a.end
}
func (a Period) Start() float64 {
return a.start
}
func (a Period) End() float64 {
if a.isFull{
return 360
}
return a.end
}
func (a Period) Wide() float64 {
if a.isFull {
return 360
}
if a.start > a.end {
return 360 - (a.start - a.end)
}
return a.end - a.start
}
func (a Period) Medium() float64 {
//if a.isFull {
// return 180
//}
//if a.Empty() {
// return a.start
//}
//if a.start > a.end {
// return Norm((a.start+a.end)/2 + 180)
//}
//return (a.start + a.end) / 2
return Norm(a.start + a.Wide()/2)
}
func (a Period) MedPart(alpha float64) float64{
return Norm(a.start+a.Wide()*alpha)
}
//is dir within Period [start;end)
//Full contains any direction
//Empty has nothing
//Dir MUST be NORMED
func (a Period) Has(dir float64) bool {
return a.isFull || a.start <= dir && dir < a.end ||
a.start>a.end && (dir>=a.start || dir<a.end)
// this is slower and not inline
//if a.isFull {
// return true
//}
//dir = Norm(dir)
//if a.Empty() {
// return dir == a.start
//}
//if a.start < a.end {
// return dir >= a.start && dir < a.end
//} else {
// return dir >= a.start || dir < a.end
//}
}
func (a Period) nfHas(dir float64) bool{
return a.start <= dir && dir < a.end ||
a.start>a.end && (dir>=a.start || dir<a.end)
}
//HasIn is Has without a.start point, so for period it is (start;end)
//Rays have nothing within
//Dir MUST be NORMED
func (a Period) HasIn(dir float64) bool {
return a.isFull || a.start < dir && dir < a.end ||
a.start>a.end && (dir>a.start || dir<a.end)
// this is slower and not inline
// if a.isFull {
// return true
// }
// if a.Empty() {
// return false
// }
// dir = Norm(dir)
// if a.start < a.end {
// return dir > a.start && dir < a.end
// } else {
// return dir > a.start || dir < a.end
// }
}
func (a Period) IsIntersect(b Period) bool{
return a.Has(b.start) || b.Has(a.start)
//this is much slower somehow
//as,ae := a.start, a.end
//bs,be := b.start, b.end
//return as>ae && (bs>=as || bs<ae || be>as || be<ae) ||
// as <= bs && bs < ae ||
// as < be && be < ae ||
// a.isFull || b.isFull
}
func (a Period) Contains (b Period) bool{
return a.isFull || (a.nfHas(b.start) && !b.Has(a.end))
}
//Intersect returns number of intersection (0-2) and their values
//Rays may intersect equal Ray or period containing ray's direction, result is ray
//Periods touching one start-end point do not intersect in it,
//so intersect results on non-ray periods can't be a ray
func (a Period) Intersect(b Period) (n int, periods [2]Period) {
if a.isFull {
return 1, [2]Period{b, EmptyPeriod}
}
if b.isFull {
return 1, [2]Period{a, EmptyPeriod}
}
if a.Empty() {
if b.Has(a.start) {
return 1, [2]Period{a, EmptyPeriod}
} else {
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
}
}
if b.Empty() {
if a.Has(b.start) {
return 1, [2]Period{b, EmptyPeriod}
} else {
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
}
}
if a.Has(b.start) && b.Has(a.start) {
return 2, [2]Period{newPeriod(b.start, a.end), newPeriod(a.start, b.end)}
}
if a.Has(b.start) {
return 1, [2]Period{newPeriod(b.start, a.end), EmptyPeriod}
}
if b.Has(a.start) {
return 1, [2]Period{newPeriod(a.start, b.end), EmptyPeriod}
}
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
}
//Sub subtracts b from a period, returning number of, and parts
//Ray subtracted from equal ray deletes it.
//Ray subtracted from period is no-op.
func (a Period) Sub(b Period) (n int, periods [2]Period) {
if b.isFull {
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
}
if b.Empty() {
if a == b {
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
} else {
return 1, [2]Period{a, EmptyPeriod}
}
}
if a.Empty() {
if b.Has(a.start) {
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
} else {
return 1, [2]Period{a, EmptyPeriod}
}
}
if a.isFull {
return 1, [2]Period{newPeriod(b.end, b.start), EmptyPeriod}
}
//both a and b here are periods, not rays or full
if a.HasIn(b.start) && a.HasIn(b.end) {
return 2, [2]Period{newPeriod(a.start, b.start), newPeriod(b.end, a.end)}
}
if a.HasIn(b.end) {
return 1, [2]Period{newPeriod(b.end, a.end), EmptyPeriod}
}
if a.HasIn(b.start) {
return 1, [2]Period{newPeriod(a.start, b.start), EmptyPeriod}
}
if b.Has(a.start){
return 0, [2]Period{EmptyPeriod, EmptyPeriod}
}
return 1, [2]Period{a, EmptyPeriod}
}
func (a Period) Split(b Period) (n int, periods[3] Period) {
intersectN, is := a.Intersect(b)
SubN, ss := a.Sub(b)
n = intersectN + SubN
for i:=0;i<intersectN;i++{
periods[i]=is[i]
}
for i:=0;i<SubN;i++{
periods[intersectN+i] = ss[i]
}
return n,periods
}
//put angle in degs in [0;360) range
func Norm(angle float64) float64 {
if angle < 0 {
a := float64(int(-angle/360) + 1)
return angle + 360*a
}
if angle >= 360 {
a := float64(int(angle / 360))
return angle - 360*a
}
return angle
}
//normalize start angle in [0;360) and end in [start; start+360]
//so always end >= start. End value itself may be more than 360
func NormRange(ang1, ang2 float64) (float64, float64) {
start, end := ang1, ang2
if start > end {
start, end = end, start
}
d := end - start
start = Norm(start)
if d == 0 {
return start, start
}
d = Norm(d)
if d == 0 {
d = 360
}
return start, start + d
}