50 lines
1.5 KiB
Go
50 lines
1.5 KiB
Go
package basic
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import (
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. "b612.me/astro/tools"
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"math"
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)
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//地球常数
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const (
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EARTH_EQUATORIAL_RADIUS float64 = 6378137.0
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EARTH_POLAR_RADIUS float64 = 6356752.3
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EARTH_AVERAGE_RADIUS float64 = 6371393.0
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)
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// HeightDistance 高度与地平线距离的关系（单位：米）
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func HeightDistance(height float64) float64 {
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return math.Acos((EARTH_AVERAGE_RADIUS)/(EARTH_AVERAGE_RADIUS+height)) * EARTH_AVERAGE_RADIUS
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}
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// HeightDistance 高度（单位：米）与地平线下角度的关系（单位：度）
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func HeightDegree(height float64) float64 {
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return math.Acos((EARTH_AVERAGE_RADIUS)/(EARTH_AVERAGE_RADIUS+height)) * 180 / math.Pi / 2
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}
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// HeightDistanceByLat 不同纬度下高度与地平线距离的关系（单位：米）
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func HeightDistanceByLat(height, lat float64) float64 {
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raduis := GeocentricRadius(lat)
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return math.Acos((raduis)/(raduis+height)) * raduis
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}
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// HeightDegreeByLat 不同纬度下高度（单位：米）与地平线下角度的关系（单位：度）
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func HeightDegreeByLat(height, lat float64) float64 {
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raduis := GeocentricRadius(lat)
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return math.Acos((raduis)/(raduis+height)) * 180 / math.Pi / 2
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}
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// GeocentricRadius 地心直径与纬度的关系
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func GeocentricRadius(lat float64) float64 {
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a := (EARTH_EQUATORIAL_RADIUS * EARTH_EQUATORIAL_RADIUS * Cos(lat))
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a *= a
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b := (EARTH_POLAR_RADIUS * EARTH_POLAR_RADIUS * Sin(lat))
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b *= b
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c := (EARTH_EQUATORIAL_RADIUS * Cos(lat))
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c *= c
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d := (EARTH_POLAR_RADIUS * Sin(lat))
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d *= d
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return math.Sqrt((a + b) / (c + d))
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}
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