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
106 lines
4.1 KiB
Go
106 lines
4.1 KiB
Go
package occultationgeo
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import (
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"math"
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"time"
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"b612.me/astro/basic"
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"b612.me/astro/internal/geodata"
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)
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const defaultRiseSetProjectedSpacingKM = 35.0
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// DensifyRiseSetCurves 按投影距离插入大地线样本，且不改变端点和分支拓扑。
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// DensifyRiseSetCurves inserts geodesic samples using the projected distance
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// consumed by map renderers. Rise/set solvers intentionally use a coarser time
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// step for performance; using those raw vertices as SVG/GeoJSON linework makes
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// high-latitude curves visibly angular even when the physical path is smooth.
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// Endpoints, phase, direction, and segment topology are preserved exactly.
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func DensifyRiseSetCurves(
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curves []basic.OccultationRiseSetCurve,
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maximumProjectedSpacingKM float64,
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) []basic.OccultationRiseSetCurve {
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if len(curves) == 0 || maximumProjectedSpacingKM <= 0 {
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return curves
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}
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result := make([]basic.OccultationRiseSetCurve, len(curves))
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for curveIndex, curve := range curves {
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result[curveIndex] = basic.OccultationRiseSetCurve{
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Phase: curve.Phase, Direction: curve.Direction,
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Segments: make([][]basic.OccultationPathPoint, len(curve.Segments)),
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}
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for segmentIndex, segment := range curve.Segments {
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result[curveIndex].Segments[segmentIndex] = densifyRiseSetSegment(segment, maximumProjectedSpacingKM)
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}
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}
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return result
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}
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// DensifyOccultationPathPoints 将相同的投影感知间距应用于单条月掩路径。
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// DensifyOccultationPathPoints applies the same projection-aware spacing to a
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// standalone geographic line such as a horizon connector. It keeps both
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// endpoints and does not attach phase metadata to the result.
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func DensifyOccultationPathPoints(
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points []basic.OccultationPathPoint,
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maximumProjectedSpacingKM float64,
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) []basic.OccultationPathPoint {
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return densifyRiseSetSegment(points, maximumProjectedSpacingKM)
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}
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func densifyRiseSetSegment(
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segment []basic.OccultationPathPoint,
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maximumProjectedSpacingKM float64,
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) []basic.OccultationPathPoint {
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if len(segment) < 2 {
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return append([]basic.OccultationPathPoint(nil), segment...)
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}
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result := make([]basic.OccultationPathPoint, 0, len(segment)*2)
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// The interpolation is geodesic on the sphere, while the spacing check is
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// made in Web Mercator. A chord that is exactly at the projected limit can
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// grow slightly after interpolation because Mercator is nonlinear in
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// latitude. Keep a small margin so the emitted linework stays below the
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// requested limit after projection.
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effectiveSpacingKM := maximumProjectedSpacingKM * 0.75
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for index, point := range segment {
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result = append(result, point)
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if index+1 >= len(segment) {
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continue
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}
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next := segment[index+1]
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steps := int(math.Ceil(projectedGeoPointDistanceKM(point, next) / effectiveSpacingKM))
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if steps < 2 {
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continue
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}
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for step := 1; step < steps; step++ {
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fraction := float64(step) / float64(steps)
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middle := interpolateOccultationGeoPoint(
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geodata.GeoPoint{Longitude: point.Longitude, Latitude: point.Latitude},
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geodata.GeoPoint{Longitude: next.Longitude, Latitude: next.Latitude},
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fraction,
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)
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result = append(result, basic.OccultationPathPoint{
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Time: point.Time.Add(time.Duration(float64(next.Time.Sub(point.Time)) * fraction)),
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Longitude: middle.Longitude,
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Latitude: middle.Latitude,
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MoonAltitude: point.MoonAltitude + (next.MoonAltitude-point.MoonAltitude)*fraction,
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WidthKM: point.WidthKM + (next.WidthKM-point.WidthKM)*fraction,
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})
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}
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}
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return result
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}
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func projectedGeoPointDistanceKM(first, second basic.OccultationPathPoint) float64 {
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const maxLatitude = 85.05112878
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const radiusKM = 6378.1366
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clampLatitude := func(value float64) float64 {
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return math.Max(-maxLatitude, math.Min(maxLatitude, value))
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}
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longitude := math.Remainder(second.Longitude-first.Longitude, 360) * math.Pi / 180
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firstLatitude := clampLatitude(first.Latitude) * math.Pi / 180
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secondLatitude := clampLatitude(second.Latitude) * math.Pi / 180
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firstY := math.Log(math.Tan(math.Pi/4 + firstLatitude/2))
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secondY := math.Log(math.Tan(math.Pi/4 + secondLatitude/2))
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return radiusKM * math.Hypot(longitude, secondY-firstY)
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}
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