/// <summary>
/// Calculate velocity for binary members and assign.
/// reflect: One of the bodies positions and velocities must be reflected to opposite side of ellipse
/// </summary>
private void SetupBody(NBody nbody, float a_n, float mu, bool reflect)
{
float a_phy = a_n / GravityEngine.instance.physToWorldFactor;
// Phase is TRUE anomoly f
float f = phase * Mathf.Deg2Rad;
float reflect_in_y = 1f;
if (reflect)
{
reflect_in_y = -1f;
//f = f + Mathf.PI;
}
// Murray and Dermott (2.20)
float r = a_phy * (1f - ecc * ecc) / (1f + ecc * Mathf.Cos(f));
// (2.26) mu = n^2 a^3 (n is period, aka T)
float n = Mathf.Sqrt(mu * GravityEngine.Instance().massScale / (a_phy * a_phy * a_phy));
// (2.36)
float denom = Mathf.Sqrt(1f - ecc * ecc);
float xdot = -1f * n * a_phy * Mathf.Sin(f) / denom;
float ydot = n * a_phy * (ecc + Mathf.Cos(f)) / denom;
Vector3 position_xy = new Vector3(reflect_in_y * r * Mathf.Cos(f), r * Mathf.Sin(f), 0);
// move from XY plane to the orbital plane and scale to world space
// orbit position is WRT center
Vector3 position = ellipse_orientation * position_xy;
// ISSUE: Problematic in case where added after the fact
position += cmPosition;
nbody.initialPhysPosition = position;
Vector3 v_xy = new Vector3(xdot, ydot, 0);
v_xy *= reflect_in_y;
// velocity will be scaled when NBody is scaled
Vector3 vel_phys = Vector3.zero;
if (binaryNbody != null)
{
// use CM velocity from parent for e.g. binary in orbit around something
vel_phys = binaryNbody.vel_phys;
}
else
{
vel_phys = velocity * GravityScaler.GetVelocityScale();
}
nbody.vel_phys = ellipse_orientation * v_xy + vel_phys;
}
/// <summary>
/// Validation:
/// - confirmed velocity in SI units matches expected orbital velocity of ISS
/// - checked that SI acceleration = -g at terminal velocity (9.73 m/s^2 at 28 km)
/// </summary>
// Use this for initialization
void Start()
{
if (inertialMassKg == 0)
{
Debug.LogError("Mass is zero. Drag calculation will fail.");
}
if (spaceship == null)
{
spaceship = GetComponent <NBody>();
}
geDistanceToKm = 1;
v_ship = new double[] { 0, 0, 0 };
v_earth = new double[] { 0, 0, 0 };
velocityScaleInternalToSI = GravityScaler.VelocityScaletoSIUnits() / GravityScaler.GetVelocityScale();
accelSItoGE = GravityScaler.AccelSItoGEUnits() / GravityScaler.AccelerationScaleInternalToGEUnits();
LoadDensityProfile();
liveState = GravityEngine.Instance().GetWorldState();
}
/// <summary>
/// Set the deltaV for a scalar maneuver in world units (e.g. in ORBITAL
/// units set velocity in km/hr)
/// </summary>
/// <param name="newDv"></param>
public void SetDvScaled(float newDv)
{
dV = newDv * GravityScaler.GetVelocityScale();
}
/// <summary>
/// Return the dV in scaled units.
/// </summary>
/// <returns></returns>
public float GetDvScaled()
{
return(dV / GravityScaler.GetVelocityScale());
}
/// <summary>
/// Set the velocity change vector in world units (e.g. in ORBITAL
/// units set velocity in km/hr)
/// </summary>
/// <param name="newVel"></param>
public void SetVelScaled(Vector3 newVel)
{
velChange = newVel * GravityScaler.GetVelocityScale();
}