MotherShip.UpdatePlanets C# (CSharp) Method

    public Vector3 UpdatePlanets()
    {
        for (int i = 0; i < this.Planets.Count; i++) {
            KeyValuePair<Planet, float> p = this.Planets [i];
            float dist = (p.Key.TruePos.TruePos - this.TruePos.TruePos).magnitude;
            this.Planets [i] = new KeyValuePair<Planet, float> (p.Key, dist);

            if (i - 1 >= 0) {
                KeyValuePair<Planet, float> pPrev = this.Planets [i - 1];
                if (p.Value < pPrev.Value) {
                    this.Planets [i] = pPrev;
                    this.Planets [i - 1] = p;
                    if (this.SelectedPlanetIndex == i) {
                        this.SelectedPlanetIndex = i - 1;
                    }
                    else if (this.SelectedPlanetIndex == i - 1) {
                        this.SelectedPlanetIndex = i;
                    }
                }
            }
        }

        Vector3 gravity = this.Planets [0].Key.Grav.GetAttractionFor (this.gameObject);

        float altitude = this.Planets [0].Value - this.Planets [0].Key.radius;
        float a = (this.Planets [0].Key.atmRange - altitude) / this.Planets [0].Key.atmRange * this.Planets [0].Key.atmDensity;;
        if (a > 0) {
            this.localAtm += a;
        }

        return gravity;
    }