55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
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package ephem
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import (
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"errors"
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"reflect"
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)
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// Body NAIF 天体编号 / NAIF body code.
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type Body int
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const (
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SSB Body = 0
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Mercury Body = 1
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Venus Body = 2
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EMB Body = 3
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Mars Body = 4
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Jupiter Body = 5
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Saturn Body = 6
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Uranus Body = 7
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Neptune Body = 8
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Sun Body = 10
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Moon Body = 301
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Earth Body = 399
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)
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var (
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// ErrOutOfRange 时刻超出星历覆盖 / epoch outside the ephemeris coverage.
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ErrOutOfRange = errors.New("ephem: epoch outside coverage")
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// ErrUnsupportedBody 星历不含该天体 / body not provided by the ephemeris.
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ErrUnsupportedBody = errors.New("ephem: unsupported body")
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// ErrNoEngine 实例未配置引擎 / instance has no engine.
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ErrNoEngine = errors.New("ephem: instance has no engine")
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// ErrUnsupportedApparent 引擎不支持视位置 / engine does not support apparent positions.
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ErrUnsupportedApparent = errors.New("ephem: apparent positions are unsupported")
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)
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// Engine 几何星历：ICRF 赤道，km 与 km/日，时间 TDB；只读、可并发 / geometric ephemeris in ICRF, km and km/day, TDB.
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type Engine interface {
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State(target, center Body, jdTDB float64) (pos, vel [3]float64, err error)
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Coverage(target Body) (start, end float64, ok bool)
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}
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// IsNilEngine 引擎为 nil 或持有 nil 指针等空值 / engine is nil or wraps a nil value.
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func IsNilEngine(engine Engine) bool {
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if engine == nil {
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return true
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}
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value := reflect.ValueOf(engine)
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switch value.Kind() {
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case reflect.Ptr, reflect.Map, reflect.Slice, reflect.Func, reflect.Interface:
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return value.IsNil()
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}
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return false
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}
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