main.go

package main

import "math"

type CartesianPoint struct {
  x, y, z float32
}

// set Spherical location from Cartesian location
func (vector *CartesianPoint) ToSpherical () SphericalPoint {
  // only calculate once when used twice
  radius := math.Sqrt(math.Pow(vector.x, 2) + math.Pow(vector.y, 2) + math.Pow(vector.z, 2))

  return SphericalPoint{
    radius: radius,
    theta: math.Acos(vector.z / radius),
    phi: math.Atan(vector.y / vector.x)
  }
}

// spherical coordinates of Instance
// asimuth/phi is North/South, polar/theta is East/West
// azimuth/phi and polar/theta are in radians
type SphericalPoint struct {
  radius, theta, phi float32
}

// set Cartesian location from Spherical location
func (vector *SphericalPoint) ToCartesian () CartesianPoint {
  // only calculate the sine of azimuth once
  sinPhi := math.Sin(vector.phi)

  return CartesianVector{
    x: vector.radius * sinPhi * math.Cos(vector.theta),
    y: vector.radius * sinPhi * math.Sin(vector.theta),
    z: vector.radius * math.Cos(vector.phi)
  }
}