sphere2xy.lua


NAME
    sphere2xy

FUNCTION
    sphere2xy(r, x, y, z)

NOTES
    Convert x, y, z on a sphere object with radius r to longitude and latitude in degree.

INPUTS
    x, y, x  - coordinate

OUTPUTS
    longitude (0 to 360) and latitude (-90 to 90) in degree.

SOURCE

function sphere2xy(r, x, y, z)
    local c = 57.29577951
    lat = c * math.asin(z/r)
    r = math.sqrt(x*x + y*y) + 1.e-15
    lon = c * math.acos(x/r)
    if y < 0 then lon = 360 - lon end
    return lon, lat
end