254 lines
9.7 KiB
Go
254 lines
9.7 KiB
Go
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package basic
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import (
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"fmt"
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"math"
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"testing"
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"b612.me/astro/internal/geodata"
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)
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func TestSolarEclipsePathTopologyAcrossSarosAnchors(t *testing.T) {
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for _, year := range []int{1526, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2526} {
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events := solarEclipseScanEvents(JDECalc(year, 1, 1), JDECalc(year+1, 1, 1))
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if len(events) == 0 {
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t.Fatalf("%d has no solar eclipse candidate", year)
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}
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eventJDE := events[0]
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name := JDE2Date(eventJDE).Format("2006-01-02")
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t.Run(name, func(t *testing.T) {
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assertSolarEclipsePathTopology(t, eventJDE, 60.0/1440.0)
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})
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}
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}
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func assertSolarEclipsePathTopology(t *testing.T, eventJDE, stepDays float64) {
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t.Helper()
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issues := solarEclipsePathTopologyIssues(eventJDE, stepDays)
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if len(issues) > 0 {
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t.Fatalf("path topology issues: %s", issues[0])
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}
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}
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func solarEclipsePathTopologyIssues(eventJDE, stepDays float64) []string {
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result := SolarEclipsePartialFootprints(eventJDE, SolarEclipsePartialFootprintOptions{
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StepDays: stepDays, BoundaryPoints: 24, DisableRiseSetCurves: true,
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})
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issues := make([]string, 0)
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if !result.Eclipse.HasPartial {
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return []string{"partial eclipse result is missing"}
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}
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contacts := []SolarEclipsePathPoint{result.P1, result.P2, result.P3, result.P4}
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previous := 0.0
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for index, contact := range contacts {
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if contact.JDE == 0 {
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continue
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}
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if previous != 0 && contact.JDE <= previous {
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issues = append(issues, fmt.Sprintf("penumbral contacts not increasing at %d", index))
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}
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previous = contact.JDE
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}
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centralContacts := []SolarEclipsePathPoint{result.U1, result.U2, result.U3, result.U4}
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previous = 0
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for index, contact := range centralContacts {
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if contact.JDE == 0 {
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continue
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}
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if previous != 0 && contact.JDE <= previous {
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issues = append(issues, fmt.Sprintf("central contacts not increasing at %d", index))
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}
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previous = contact.JDE
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}
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for footprintIndex, footprint := range append(append([]SolarEclipsePartialFootprint(nil), result.Footprints...), result.CentralShadowFootprints...) {
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totalBoundaryPoints := 0
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for _, boundary := range footprint.Boundaries {
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totalBoundaryPoints += len(boundary)
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}
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for boundaryIndex, boundary := range footprint.Boundaries {
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if len(boundary) < 2 && (footprint.Closed || totalBoundaryPoints != 1) {
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issues = append(issues, fmt.Sprintf("footprint %d boundary %d is too short", footprintIndex, boundaryIndex))
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continue
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}
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for pointIndex, point := range boundary {
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if !finite(point.JDE) || !finite(point.Longitude) || !finite(point.Latitude) ||
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point.Longitude < -180 || point.Longitude > 180 || point.Latitude < -90 || point.Latitude > 90 {
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issues = append(issues, fmt.Sprintf("footprint %d boundary %d point %d is invalid", footprintIndex, boundaryIndex, pointIndex))
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}
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if pointIndex > 0 && solarEclipsePathDistanceKM(boundary[pointIndex-1], point) > 12000 {
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issues = append(issues, fmt.Sprintf("footprint %d boundary %d has a discontinuity", footprintIndex, boundaryIndex))
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}
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}
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}
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if footprint.Closed {
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if len(footprint.Boundaries) == 0 {
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issues = append(issues, fmt.Sprintf("closed footprint %d has no boundary", footprintIndex))
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}
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}
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}
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if result.Eclipse.HasCentral {
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// Limit derivation needs the normal one-minute tangent samples. A
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// coarse diagnostic footprint step can leave only two center points and
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// is intentionally not reused for the paired cross-sections.
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centralStepDays := solarEclipsePathDefaultStepDays
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path := SolarEclipseCentralPath(eventJDE, SolarEclipsePathOptions{StepDays: centralStepDays})
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if len(path.CenterLine) < 2 || len(path.NorthernLimit) < 2 || len(path.NorthernLimit) != len(path.SouthernLimit) {
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issues = append(issues, "central path or paired limits are incomplete")
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}
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for index := 1; index < len(path.CenterLine); index++ {
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if path.CenterLine[index].JDE <= path.CenterLine[index-1].JDE {
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issues = append(issues, "center-line times are not increasing")
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break
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}
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}
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for index := 1; index < len(path.NorthernLimit); index++ {
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if path.NorthernLimit[index].JDE <= path.NorthernLimit[index-1].JDE ||
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path.SouthernLimit[index].JDE <= path.SouthernLimit[index-1].JDE {
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issues = append(issues, "central-limit times are not increasing")
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break
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}
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insideTwoLimitPath := result.Eclipse.Centrality == SolarEclipseCentralTwoLimits &&
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index > 1 && index < len(path.NorthernLimit)-1
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northGap := solarEclipsePathDistanceKM(path.NorthernLimit[index-1], path.NorthernLimit[index]) > 500 &&
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!(math.Abs(path.NorthernLimit[index-1].Latitude) > 80 && math.Abs(path.NorthernLimit[index].Latitude) > 80)
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southGap := solarEclipsePathDistanceKM(path.SouthernLimit[index-1], path.SouthernLimit[index]) > 500 &&
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!(math.Abs(path.SouthernLimit[index-1].Latitude) > 80 && math.Abs(path.SouthernLimit[index].Latitude) > 80)
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if insideTwoLimitPath && (northGap || southGap) {
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issues = append(issues, "central-limit branch has a gap above 500 km")
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break
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}
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}
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if len(path.CenterLine) >= 2 {
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first := path.CenterLine[0]
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last := path.CenterLine[len(path.CenterLine)-1]
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if math.Abs(first.SunAltitude) > 0.02 || math.Abs(last.SunAltitude) > 0.02 {
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issues = append(issues, fmt.Sprintf(
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"center-line limits are off the horizon: first=%.6f last=%.6f",
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first.SunAltitude, last.SunAltitude,
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))
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}
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if !finite(first.WidthKM) || !finite(last.WidthKM) ||
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first.WidthKM < 0 || last.WidthKM < 0 || first.WidthKM > 5000 || last.WidthKM > 5000 {
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issues = append(issues, fmt.Sprintf(
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"center-line limit widths are invalid: first=%.3f last=%.3f",
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first.WidthKM, last.WidthKM,
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))
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}
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}
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} else if result.Eclipse.Type != SolarEclipsePartial && result.Eclipse.Centrality == SolarEclipseNonCentral {
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if len(result.CentralBandSegments) == 0 {
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if err := auditSolarEclipseOpenBandSweep(result.CentralBandFootprints); err != nil {
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issues = append(issues, "non-central eclipse has no usable central band: "+err.Error())
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}
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}
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for index, segment := range result.CentralBandSegments {
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if len(segment) < 4 || solarEclipsePathDistanceKM(segment[0], segment[len(segment)-1]) > 0.1 {
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issues = append(issues, fmt.Sprintf("non-central band segment %d is not closed", index))
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}
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}
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if len(result.CentralBandSegments) > 0 {
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if err := auditSolarEclipseBandContainsFootprints(result.CentralBandSegments, result.CentralBandFootprints); err != nil {
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issues = append(issues, "non-central band excludes an instantaneous central-shadow boundary: "+err.Error())
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}
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}
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}
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return issues
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}
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func auditSolarEclipseBandContainsFootprints(
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segments [][]SolarEclipsePathPoint,
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footprints []SolarEclipsePartialFootprint,
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) error {
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if solarEclipseNonCentralBandContainsFootprints(segments, footprints) {
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return nil
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}
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miss := solarEclipseBandFootprintMissDistanceKM(segments, footprints)
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return fmt.Errorf("maximum boundary miss %.6f km exceeds %.3f km tolerance",
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miss, solarEclipseNonCentralBandContainmentToleranceKM)
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}
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func solarEclipseBandFootprintMissDistanceKM(
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segments [][]SolarEclipsePathPoint,
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footprints []SolarEclipsePartialFootprint,
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) float64 {
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polygons := make([][]geodata.GeoPoint, 0, len(segments))
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for _, segment := range segments {
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polygon := make([]geodata.GeoPoint, len(segment))
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for index, point := range segment {
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polygon[index] = geodata.GeoPoint{Longitude: point.Longitude, Latitude: point.Latitude}
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}
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polygons = append(polygons, polygon)
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}
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paths := make([][]geodata.GeoPoint, 0, len(footprints))
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for _, footprint := range footprints {
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for _, boundary := range footprint.Boundaries {
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path := make([]geodata.GeoPoint, len(boundary))
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for index, point := range boundary {
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path[index] = geodata.GeoPoint{Longitude: point.Longitude, Latitude: point.Latitude}
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}
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paths = append(paths, path)
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}
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}
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return geodata.SphericalPolygonsPathMissDistanceKM(polygons, paths, false)
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}
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func auditSolarEclipseOpenBandSweep(footprints []SolarEclipsePartialFootprint) error {
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samples := make([]geodata.OpenBoundarySweepSample, 0, len(footprints))
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for _, footprint := range footprints {
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boundaries := make([][]geodata.GeoPoint, 0, len(footprint.Boundaries))
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for _, boundary := range footprint.Boundaries {
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points := make([]geodata.GeoPoint, len(boundary))
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for index, point := range boundary {
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if !finite(point.Longitude) || !finite(point.Latitude) {
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return fmt.Errorf("footprint contains a non-finite point")
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}
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points[index] = geodata.GeoPoint{Longitude: point.Longitude, Latitude: point.Latitude}
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}
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boundaries = append(boundaries, points)
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}
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samples = append(samples, geodata.OpenBoundarySweepSample{
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Boundaries: boundaries,
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Closed: footprint.Closed,
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})
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}
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polygons, err := geodata.OpenBoundarySweep(samples)
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if err != nil {
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return err
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}
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if len(polygons) == 0 {
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return fmt.Errorf("open footprint sweep contains no polygon")
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}
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for polygonIndex, polygon := range polygons {
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if len(polygon) < 3 {
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return fmt.Errorf("open footprint sweep polygon %d has only %d points", polygonIndex, len(polygon))
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}
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for pointIndex, point := range polygon {
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if !finite(point.Longitude) || !finite(point.Latitude) ||
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point.Longitude < -180 || point.Longitude > 180 || point.Latitude < -90 || point.Latitude > 90 {
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return fmt.Errorf("open footprint sweep polygon %d point %d is invalid", polygonIndex, pointIndex)
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}
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}
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}
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return nil
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}
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func solarEclipseScanEvents(startJDE, endJDE float64) []float64 {
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seed := CalcMoonSHByJDE(startJDE, 0)
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if seed < startJDE {
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seed = CalcMoonSHByJDE(seed+25, 0)
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}
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var events []float64
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for seed < endJDE {
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result := SolarEclipse(seed)
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if result.HasPartial {
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events = append(events, result.GreatestEclipse)
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}
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next := CalcMoonSHByJDE(seed+25, 0)
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if !finite(next) || next <= seed+20 {
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break
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}
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seed = next
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}
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return events
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}
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