91 lines
3.7 KiB
Go
91 lines
3.7 KiB
Go
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package eclipse
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import (
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"time"
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"b612.me/astro/basic"
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)
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// SolarEclipseCandidateOptions 批量枚举配置，零值为全部食型的 NASA bulletin Split-K / enumeration options.
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type SolarEclipseCandidateOptions struct {
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// Model 月亮半径模型，零值为 NASA bulletin Split-K / lunar radius model.
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Model SolarEclipseRadiusModel
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// CentralOnly 只保留全食、环食与混合食，含中心线未落到地表的 T0/A0 事件。
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// CentralOnly keeps total, annular, and hybrid eclipses, including T0/A0 events
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// whose axis misses the Earth; the kind filter matches SearchLocalCentralSolarEclipse.
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CentralOnly bool
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// IncludeSaros 附带沙罗序列信息 / attach Saros metadata.
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IncludeSaros bool
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}
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// SolarEclipseCandidate 一场日食的时刻表条目，不含几何 / geometry-free timetable entry.
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type SolarEclipseCandidate struct {
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// GreatestEclipse 食甚时刻 / greatest-eclipse instant.
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GreatestEclipse time.Time
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// Type 全局食型，Centrality 中心食类型 / global type and centrality.
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Type SolarEclipseType
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Centrality SolarEclipseCentrality
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// Magnitude 与 Gamma 是全局食分与伽马 / global magnitude and gamma.
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Magnitude float64
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Gamma float64
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// Saros 仅在 IncludeSaros 时有效 / valid only with IncludeSaros.
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Saros SarosInfo
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HasSaros bool
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}
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// 食甚可能早于朔，枚举上界要多留这么多天。
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const solarEclipseCandidateGreatestLeadDays = 0.5
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// solarEclipseCandidateIsCentral 按全局食型判定，与站心搜索的 Kind 口径一致。
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func solarEclipseCandidateIsCentral(value basic.SolarEclipseType) bool {
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switch value {
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case basic.SolarEclipseTotal, basic.SolarEclipseAnnular, basic.SolarEclipseHybrid:
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return true
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}
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return false
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}
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// SolarEclipseCandidates 枚举区间内的日食时刻表，按时间升序 / eclipses within a range, in time order.
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func SolarEclipseCandidates(
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start, end time.Time, options SolarEclipseCandidateOptions,
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) []SolarEclipseCandidate {
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if !end.After(start) {
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return nil
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}
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calculator := localSolarEclipseCalculatorForModel(options.Model)
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startTT := solarEclipseTimeToTTJDE(start)
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endTT := solarEclipseTimeToTTJDE(end)
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candidates := make([]SolarEclipseCandidate, 0, 8)
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candidateTT := basic.CalcMoonSHByJDE(startTT, 0)
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for iteration := 0; iteration < localSolarEclipseSearchIterationCap; iteration++ {
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// 食甚可能略早于朔，上界要多留一点余量，否则窗口末尾那场会被漏掉。
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if candidateTT > endTT+solarEclipseCandidateGreatestLeadDays {
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break
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}
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if isPotentialLocalSolarEclipse(candidateTT) {
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globalResult := calculator.global(candidateTT)
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if globalResult.Type != basic.SolarEclipseNone &&
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(!options.CentralOnly || solarEclipseCandidateIsCentral(globalResult.Type)) {
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greatest := solarEclipseTTJDEToTime(globalResult.GreatestEclipse, start.Location())
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// 候选朔月取的是“最近”的朔，可能落在 start 之前或 end 之后（食甚早于朔），
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// 按食甚时刻双侧过滤；注意不能 continue：候选推进在循环末尾，跳过它会原地打转。
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if !greatest.Before(start) && !greatest.After(end) {
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candidate := SolarEclipseCandidate{
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GreatestEclipse: greatest,
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Type: mapBasicSolarEclipseType(globalResult.Type),
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Centrality: mapBasicSolarEclipseCentrality(globalResult.Centrality),
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Magnitude: globalResult.Magnitude,
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Gamma: globalResult.Gamma,
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}
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if options.IncludeSaros {
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candidate.Saros, candidate.HasSaros = solarSarosInfo(globalResult.GreatestEclipse)
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}
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candidates = append(candidates, candidate)
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}
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}
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}
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candidateTT = nextEclipseSearchCandidateTT(candidateTT, 0, 1, localSolarEclipseSynodicMonthDays)
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}
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return candidates
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}
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