b612
2bf8478639
- 新增日月食中心带、偏食带、阴影足迹、等时线、食分线及升落边界计算，支持极区与混合食拓扑 - 新增日食单时刻阴影求解器、站心状态查询、批量采样和 ΔT 覆盖接口 - 重构恒星与行星月掩路径，补充有限盘面接触、站心修正、掩带宽度、极区投影及升落边界 - 扩展 SVG 与 GeoJSON 输出，支持详细面板、全球/极区/地球投影、边界闭合、时间标记和拓扑签名 - 扩展日月食候选搜索、局地搜索、沙罗序列预计算与范围外推，补充系列锚点和成员一致性校验 - 补齐古历纪年、儒略历独有闰日、多公历候选、历法改革跨日及精确日期运算接口 - 优化 ΔT、章动、恒星时、月球地平线、事件根搜索和本地星历缓存，降低重复计算开销并提升边界稳定
121 lines
3.6 KiB
Go
121 lines
3.6 KiB
Go
package svg
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import (
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"math"
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"sync"
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"b612.me/astro/internal/geodata"
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"b612.me/astro/moon"
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)
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// occultationBandPolygons 是一次紧凑掩带合并的只读结果。
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type occultationBandPolygons struct {
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polygons [][]geodata.GeoPoint
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authoritative bool
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}
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type occultationBandCacheKey struct {
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kind occultationFootprintSweepKind
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digest [2]uint64
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}
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// occultationBandCacheCapacity 限制常驻的合并结果数量；掩带多边形可能上万点。
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const occultationBandCacheCapacity = 6
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var occultationBandCache = struct {
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sync.RWMutex
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entries map[occultationBandCacheKey]occultationBandPolygons
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order []occultationBandCacheKey
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}{entries: make(map[occultationBandCacheKey]occultationBandPolygons, occultationBandCacheCapacity)}
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func lookupOccultationBandPolygons(key occultationBandCacheKey) (occultationBandPolygons, bool) {
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occultationBandCache.RLock()
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value, ok := occultationBandCache.entries[key]
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occultationBandCache.RUnlock()
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return value, ok
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}
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func storeOccultationBandPolygons(key occultationBandCacheKey, value occultationBandPolygons) {
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occultationBandCache.Lock()
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defer occultationBandCache.Unlock()
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if _, exists := occultationBandCache.entries[key]; exists {
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return
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}
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if len(occultationBandCache.order) >= occultationBandCacheCapacity {
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delete(occultationBandCache.entries, occultationBandCache.order[0])
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occultationBandCache.order = occultationBandCache.order[1:]
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}
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occultationBandCache.entries[key] = value
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occultationBandCache.order = append(occultationBandCache.order, key)
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}
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// occultationBandDigest 汇总合并的全部输入；按 64 位字混合而不是逐字节，摘要成本必须远低于合并本身。
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func occultationBandDigest(s occultationFootprintSweep) [2]uint64 {
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const (
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seed1 = 0x9e3779b97f4a7c15
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seed2 = 0xc2b2ae3d27d4eb4f
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prime = 0x100000001b3
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)
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first, second := uint64(seed1), uint64(seed2)
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write := func(value uint64) {
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first = (first ^ value) * prime
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first ^= first >> 31
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second = (second + value) * prime
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second ^= second >> 33
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}
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writeFloat := func(value float64) { write(math.Float64bits(value)) }
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writeTime := func(value int64) { write(uint64(value)) }
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writePoint := func(point moon.OccultationPathPoint) {
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writeTime(point.Time.UnixNano())
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writeFloat(point.Longitude)
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writeFloat(point.Latitude)
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writeFloat(point.MoonAltitude)
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writeFloat(point.WidthKM)
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writeFloat(point.LimitSeparationKM)
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}
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writePolygons := func(polygons [][]moon.OccultationPathPoint) {
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write(uint64(len(polygons)))
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for _, polygon := range polygons {
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write(uint64(len(polygon)))
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for _, point := range polygon {
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writePoint(point)
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}
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}
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}
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writeString := func(value string) {
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write(uint64(len(value)))
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for index := 0; index < len(value); index++ {
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write(uint64(value[index]))
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}
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}
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writeFootprints := func(footprints []moon.PlanetOccultationFootprint) {
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write(uint64(len(footprints)))
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for _, footprint := range footprints {
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writeTime(footprint.Time.UnixNano())
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writePolygons(footprint.Polygons)
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writePolygons(footprint.InteriorPolygons)
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writePolygons(footprint.Boundaries)
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if footprint.Closed {
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write(1)
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} else {
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write(0)
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}
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}
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}
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writeCurves := func(curves []moon.OccultationRiseSetCurve) {
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write(uint64(len(curves)))
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for _, curve := range curves {
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writeString(string(curve.Phase))
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writeString(string(curve.Direction))
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writePolygons(curve.Segments)
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}
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}
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write(uint64(s.kind))
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writeFootprints(s.footprints)
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writePolygons(s.contours)
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writePolygons(s.visibilityContours)
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writePolygons([][]moon.OccultationPathPoint{s.northern, s.southern})
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writeCurves(s.curves)
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return [2]uint64{first, second}
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}
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