279 lines
13 KiB
Go
279 lines
13 KiB
Go
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package eclipse
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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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)
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// SolarEclipsePathOptions 控制日食中心路径采样。
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// SolarEclipsePathOptions controls central solar eclipse path sampling.
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type SolarEclipsePathOptions struct {
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// Step 是基础时间采样步长；<=0 时使用 1 分钟。
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// Step is the base time step; values <= 0 use one minute.
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Step time.Duration
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// TargetSpacingKM 是相邻中心线点的最大目标地表距离；<=0 时不按距离加密。
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// TargetSpacingKM is the target maximum ground spacing between centerline points; values <= 0 disable spacing refinement.
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TargetSpacingKM float64
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}
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// SolarEclipsePathPoint 表示日食路径上的一个地理点。
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// SolarEclipsePathPoint is one geographic point on a solar eclipse path.
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type SolarEclipsePathPoint struct {
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// Time 时刻，保持用户输入时区, time in the input location.
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Time time.Time
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// Longitude 经度，东正西负, longitude in degrees, east positive.
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Longitude float64
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// Latitude 纬度，北正南负, latitude in degrees, north positive.
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Latitude float64
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// SunAltitude 太阳高度角，单位度, Sun altitude in degrees.
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SunAltitude float64
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// WidthKM 中心食带宽度，单位千米；仅中心线点有意义。
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// WidthKM is the central path width in kilometers; meaningful for centerline points.
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WidthKM float64
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}
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// SolarEclipsePath 表示一次中心日食的路径数据。
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// SolarEclipsePath contains central solar eclipse path data.
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type SolarEclipsePath struct {
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// Eclipse 是对应的全局日食信息, related global solar eclipse information.
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Eclipse SolarEclipseInfo
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// Greatest 是食甚点/最佳观测点, greatest eclipse point.
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Greatest SolarEclipsePathPoint
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// CenterLine 是中心线, central line.
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CenterLine []SolarEclipsePathPoint
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// NorthernLimit 是中心食带北界近似线, approximate northern limit of the central path.
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NorthernLimit []SolarEclipsePathPoint
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// SouthernLimit 是中心食带南界近似线, approximate southern limit of the central path.
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SouthernLimit []SolarEclipsePathPoint
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// Step 是实际采用的基础时间采样步长, effective base time step.
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Step time.Duration
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// TargetSpacingKM 是实际采用的目标空间采样距离，单位千米。
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// TargetSpacingKM is the effective target spacing in kilometers.
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TargetSpacingKM float64
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}
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// SolarEclipsePartialFootprintOptions 控制日食偏食半影足迹采样。
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// SolarEclipsePartialFootprintOptions controls solar eclipse penumbral footprint sampling.
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type SolarEclipsePartialFootprintOptions struct {
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// Step 是基础时间采样步长；<=0 时使用 5 分钟。
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// Step is the base time step; values <= 0 use five minutes.
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Step time.Duration
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// BoundaryPoints 是每个瞬时半影边界的角向采样点数；<=0 时使用 180。
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// BoundaryPoints is the angular sample count for each instantaneous penumbral boundary; values <= 0 use 180.
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BoundaryPoints int
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}
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// SolarEclipsePartialAreaOptions 是 SolarEclipsePartialFootprintOptions 的兼容别名。
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// SolarEclipsePartialAreaOptions is a compatibility alias for SolarEclipsePartialFootprintOptions.
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type SolarEclipsePartialAreaOptions = SolarEclipsePartialFootprintOptions
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// SolarEclipsePartialFootprint 表示某一时刻的半影足迹边界。
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// SolarEclipsePartialFootprint is the penumbral footprint boundary at one instant.
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type SolarEclipsePartialFootprint struct {
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// Time 时刻，保持用户输入时区, time in the input location.
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Time time.Time
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// Boundaries 是半影边界分段；反经线或无效投影会拆成多段。
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// Boundaries are segmented penumbral boundary polylines, split at invalid projections or the antimeridian.
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Boundaries [][]SolarEclipsePathPoint
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// Closed 表示 Boundaries 是否构成一个闭合边界。
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// Closed indicates whether Boundaries form one closed boundary.
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Closed bool
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}
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// SolarEclipsePartialFootprintsInfo 表示一次日食的偏食半影足迹序列。
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// SolarEclipsePartialFootprintsInfo contains penumbral footprint samples for a solar eclipse.
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type SolarEclipsePartialFootprintsInfo struct {
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// Eclipse 是对应的全局日食信息, related global solar eclipse information.
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Eclipse SolarEclipseInfo
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// Footprints 是按时间采样的瞬时半影足迹, sampled instantaneous penumbral footprints.
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Footprints []SolarEclipsePartialFootprint
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// Step 是实际采用的基础时间采样步长, effective base time step.
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Step time.Duration
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// BoundaryPoints 是实际采用的边界角向采样点数。
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// BoundaryPoints is the effective angular sample count for each boundary.
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BoundaryPoints int
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}
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// SolarEclipsePartialAreaInfo 是 SolarEclipsePartialFootprintsInfo 的兼容别名。
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// SolarEclipsePartialAreaInfo is a compatibility alias for SolarEclipsePartialFootprintsInfo.
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type SolarEclipsePartialAreaInfo = SolarEclipsePartialFootprintsInfo
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type solarEclipsePathCalculator func(float64, basic.SolarEclipsePathOptions) basic.SolarEclipsePathResult
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type solarEclipsePartialFootprintsCalculator func(float64, basic.SolarEclipsePartialFootprintOptions) basic.SolarEclipsePartialFootprintsResult
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// SolarEclipseCentralPath 日食中心路径查询 / central solar eclipse path query.
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// SolarEclipseCentralPath computes the central path near the given date, using NASA bulletin Split-K by default.
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func SolarEclipseCentralPath(date time.Time, options SolarEclipsePathOptions) (SolarEclipsePath, bool) {
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return SolarEclipseCentralPathNASABulletinSplitK(date, options)
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}
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// SolarEclipseCentralPathNASABulletinSplitK 日食中心路径查询（NASA bulletin Split-K） / central solar eclipse path query with NASA bulletin Split-K.
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// SolarEclipseCentralPathNASABulletinSplitK computes the central path with the NASA bulletin Split-K model.
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func SolarEclipseCentralPathNASABulletinSplitK(date time.Time, options SolarEclipsePathOptions) (SolarEclipsePath, bool) {
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return solarEclipseCentralPath(date, options, basic.SolarEclipseCentralPathNASABulletinSplitK)
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}
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// SolarEclipseCentralPathIAUSingleK 日食中心路径查询（IAU Single-K） / central solar eclipse path query with IAU Single-K.
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// SolarEclipseCentralPathIAUSingleK computes the central path with the IAU Single-K model.
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func SolarEclipseCentralPathIAUSingleK(date time.Time, options SolarEclipsePathOptions) (SolarEclipsePath, bool) {
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return solarEclipseCentralPath(date, options, basic.SolarEclipseCentralPathIAUSingleK)
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}
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// SolarEclipsePartialFootprints 日食偏食足迹查询 / solar eclipse penumbral footprints query.
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// SolarEclipsePartialFootprints computes penumbral footprint samples near the given date, using NASA bulletin Split-K by default.
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func SolarEclipsePartialFootprints(date time.Time, options SolarEclipsePartialFootprintOptions) (SolarEclipsePartialFootprintsInfo, bool) {
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return SolarEclipsePartialFootprintsNASABulletinSplitK(date, options)
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}
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// SolarEclipsePartialFootprintsNASABulletinSplitK 日食偏食足迹查询（NASA bulletin Split-K） / solar eclipse penumbral footprints query with NASA bulletin Split-K.
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// SolarEclipsePartialFootprintsNASABulletinSplitK computes penumbral footprint samples with the NASA bulletin Split-K model.
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func SolarEclipsePartialFootprintsNASABulletinSplitK(date time.Time, options SolarEclipsePartialFootprintOptions) (SolarEclipsePartialFootprintsInfo, bool) {
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return solarEclipsePartialFootprints(date, options, basic.SolarEclipsePartialFootprintsNASABulletinSplitK)
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}
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// SolarEclipsePartialFootprintsIAUSingleK 日食偏食足迹查询（IAU Single-K） / solar eclipse penumbral footprints query with IAU Single-K.
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// SolarEclipsePartialFootprintsIAUSingleK computes penumbral footprint samples with the IAU Single-K model.
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func SolarEclipsePartialFootprintsIAUSingleK(date time.Time, options SolarEclipsePartialFootprintOptions) (SolarEclipsePartialFootprintsInfo, bool) {
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return solarEclipsePartialFootprints(date, options, basic.SolarEclipsePartialFootprintsIAUSingleK)
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}
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// SolarEclipsePartialArea 偏食足迹兼容包装 / compatibility wrapper for penumbral footprints.
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// SolarEclipsePartialArea computes penumbral footprint samples and is a compatibility wrapper for SolarEclipsePartialFootprints.
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func SolarEclipsePartialArea(date time.Time, options SolarEclipsePartialAreaOptions) (SolarEclipsePartialAreaInfo, bool) {
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return SolarEclipsePartialFootprints(date, options)
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}
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// SolarEclipsePartialAreaNASABulletinSplitK 偏食足迹兼容包装（NASA bulletin Split-K） / compatibility wrapper for penumbral footprints with NASA bulletin Split-K.
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// SolarEclipsePartialAreaNASABulletinSplitK is a compatibility wrapper for SolarEclipsePartialFootprintsNASABulletinSplitK.
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func SolarEclipsePartialAreaNASABulletinSplitK(date time.Time, options SolarEclipsePartialAreaOptions) (SolarEclipsePartialAreaInfo, bool) {
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return SolarEclipsePartialFootprintsNASABulletinSplitK(date, options)
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}
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// SolarEclipsePartialAreaIAUSingleK 偏食足迹兼容包装（IAU Single-K） / compatibility wrapper for penumbral footprints with IAU Single-K.
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// SolarEclipsePartialAreaIAUSingleK is a compatibility wrapper for SolarEclipsePartialFootprintsIAUSingleK.
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func SolarEclipsePartialAreaIAUSingleK(date time.Time, options SolarEclipsePartialAreaOptions) (SolarEclipsePartialAreaInfo, bool) {
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return SolarEclipsePartialFootprintsIAUSingleK(date, options)
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}
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func solarEclipseCentralPath(
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date time.Time,
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options SolarEclipsePathOptions,
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calculator solarEclipsePathCalculator,
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) (SolarEclipsePath, bool) {
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location := date.Location()
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result := calculator(solarEclipseTimeToTTJDE(date), basicSolarEclipsePathOptions(options))
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if !result.Eclipse.HasCentral || len(result.CenterLine) == 0 {
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return SolarEclipsePath{}, false
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}
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path := SolarEclipsePath{
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Eclipse: solarEclipseInfoFromBasic(result.Eclipse, location),
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Greatest: solarEclipsePathPointFromBasic(result.Greatest, location),
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CenterLine: solarEclipsePathPointsFromBasic(result.CenterLine, location),
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NorthernLimit: solarEclipsePathPointsFromBasic(result.NorthernLimit, location),
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SouthernLimit: solarEclipsePathPointsFromBasic(result.SouthernLimit, location),
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Step: solarEclipsePathStepDuration(result.StepDays),
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TargetSpacingKM: result.TargetSpacingKM,
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}
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return path, true
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}
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func solarEclipsePartialFootprints(
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date time.Time,
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options SolarEclipsePartialFootprintOptions,
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calculator solarEclipsePartialFootprintsCalculator,
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) (SolarEclipsePartialFootprintsInfo, bool) {
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location := date.Location()
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result := calculator(solarEclipseTimeToTTJDE(date), basicSolarEclipsePartialFootprintOptions(options))
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if !result.Eclipse.HasPartial || len(result.Footprints) == 0 {
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return SolarEclipsePartialFootprintsInfo{}, false
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}
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footprints := SolarEclipsePartialFootprintsInfo{
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Eclipse: solarEclipseInfoFromBasic(result.Eclipse, location),
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Footprints: solarEclipsePartialFootprintsFromBasic(result.Footprints, location),
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Step: solarEclipsePathStepDuration(result.StepDays),
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BoundaryPoints: result.BoundaryPoints,
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}
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return footprints, true
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}
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func basicSolarEclipsePathOptions(options SolarEclipsePathOptions) basic.SolarEclipsePathOptions {
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basicOptions := basic.SolarEclipsePathOptions{
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TargetSpacingKM: options.TargetSpacingKM,
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}
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if options.Step > 0 {
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basicOptions.StepDays = options.Step.Hours() / 24
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}
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return basicOptions
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}
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func basicSolarEclipsePartialFootprintOptions(options SolarEclipsePartialFootprintOptions) basic.SolarEclipsePartialFootprintOptions {
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basicOptions := basic.SolarEclipsePartialFootprintOptions{
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BoundaryPoints: options.BoundaryPoints,
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}
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if options.Step > 0 {
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basicOptions.StepDays = options.Step.Hours() / 24
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}
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return basicOptions
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}
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func solarEclipsePathStepDuration(stepDays float64) time.Duration {
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return time.Duration(math.Round(stepDays * 24 * float64(time.Hour)))
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}
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func solarEclipsePathPointsFromBasic(points []basic.SolarEclipsePathPoint, location *time.Location) []SolarEclipsePathPoint {
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if len(points) == 0 {
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return nil
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}
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result := make([]SolarEclipsePathPoint, len(points))
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for i, point := range points {
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result[i] = solarEclipsePathPointFromBasic(point, location)
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}
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return result
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}
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func solarEclipsePathPointFromBasic(point basic.SolarEclipsePathPoint, location *time.Location) SolarEclipsePathPoint {
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return SolarEclipsePathPoint{
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Time: solarEclipseTTJDEToTime(point.JDE, location),
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Longitude: point.Longitude,
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Latitude: point.Latitude,
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SunAltitude: point.SunAltitude,
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WidthKM: point.WidthKM,
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}
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}
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func solarEclipsePartialFootprintsFromBasic(
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footprints []basic.SolarEclipsePartialFootprint,
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location *time.Location,
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) []SolarEclipsePartialFootprint {
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if len(footprints) == 0 {
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return nil
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}
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result := make([]SolarEclipsePartialFootprint, len(footprints))
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for i, footprint := range footprints {
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result[i] = SolarEclipsePartialFootprint{
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Time: solarEclipseTTJDEToTime(footprint.JDE, location),
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Boundaries: solarEclipsePartialBoundariesFromBasic(footprint.Boundaries, location),
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Closed: footprint.Closed,
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}
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}
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return result
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}
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func solarEclipsePartialBoundariesFromBasic(
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boundaries [][]basic.SolarEclipsePathPoint,
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location *time.Location,
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) [][]SolarEclipsePathPoint {
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if len(boundaries) == 0 {
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return nil
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}
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result := make([][]SolarEclipsePathPoint, len(boundaries))
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for i, boundary := range boundaries {
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result[i] = solarEclipsePathPointsFromBasic(boundary, location)
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}
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return result
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}
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