/// <summary>
/// Execute the maneuver. Called automatically by Gravity Engine for maneuvers that
/// have been added to the GE via AddManeuver().
///
/// Unusual to call this method directly.
/// </summary>
/// <param name="ge"></param>
public void Execute(GravityState gs)
{
double[] vel = new double[3] {
0, 0, 0
};
gs.GetVelocityDouble(nbody, ref vel);
switch (mtype)
{
case Mtype.vector:
vel[0] += velChange[0];
vel[1] += velChange[1];
vel[2] += velChange[2];
break;
case Mtype.scalar:
// scalar: adjust existing velocity by dV
Vector3d vel3d = new Vector3d(ref vel);
Vector3d change = Vector3d.Normalize(vel3d) * dV;
vel[0] += change[0];
vel[1] += change[1];
vel[2] += change[2];
break;
case Mtype.setv:
// direct assignement (this mode normally used for debug)
vel[0] = velChange[0];
vel[1] = velChange[1];
vel[2] = velChange[2];
break;
}
#pragma warning disable 162 // disable unreachable code warning
if (GravityEngine.DEBUG)
{
if (!gs.isAsync)
{
Debug.Log("Applied manuever: " + LogString() + " engineRef.index=" + nbody.engineRef.index +
" engineRef.bodyType=" + nbody.engineRef.bodyType + " timeError=" + (worldTime - gs.time));
Debug.LogFormat("r={0} v=({1},{2},{3}) ", Vector3.Magnitude(nbody.transform.position),
vel[0], vel[1], vel[2]);
}
}
#pragma warning restore 162 // enable unreachable code warning
gs.SetVelocityDouble(nbody, ref vel);
}
/// <summary>
/// Determine the acceleration due to atmospheric resistance.
/// </summary>
/// <param name="time">(not used)</param>
/// <param name="gravityState"></param>
/// <param name="massKg">Updated mass (0 to use the inertial mass from inspector)</param>
/// <returns></returns>
public double[] acceleration(double time, GravityState gravityState, ref double massKg)
{
bool isLiveState = (gravityState == liveState);
accel[0] = 0;
accel[1] = 0;
accel[2] = 0;
if (impact)
{
return(accel);
}
if (massKg < 1E-9)
{
massKg = inertialMassKg;
}
// determine height above Earth's surface in km
// due to dynamic add/delete cannot in general keep a cached value of the index for ship or Earth
// @TODO: Pass in this objects position to save a lookup
Vector3d earthPos = gravityState.GetPhysicsPositionDouble(earth);
Vector3d shipPos = gravityState.GetPhysicsPositionDouble(spaceship);
double h = Vector3d.Distance(earthPos, shipPos) * geDistanceToKm - heightEarthSurface;
if (h < 0)
{
if (isLiveState)
{
impact = true;
Debug.LogFormat("Impact of {0} at h={1} shipPos={2}", gameObject.name, h, shipPos);
if (impactTrigger != null)
{
impactTrigger.Impact(spaceship, gravityState);
}
return(accel);
}
else
{
return(accel);
}
}
// retrieve the density from the pre-calculated table
double hdiv10 = h / 10.0;
int densityIndex = (int)hdiv10;
if (densityIndex > densityTablePer10km.Length - 2)
{
// too far away, no drag
return(accel);
}
// interpolate.
double density = densityTablePer10km[densityIndex] +
(hdiv10 - (double)densityIndex) *
(densityTablePer10km[densityIndex + 1] - densityTablePer10km[densityIndex]);
// determine accel due to drag
gravityState.GetVelocityDouble(spaceship, ref v_ship);
gravityState.GetVelocityDouble(earth, ref v_earth);
// convert to SI
v_rel[0] = (v_ship[0] - v_earth[0]) * velocityScaleInternalToSI;
v_rel[1] = (v_ship[1] - v_earth[1]) * velocityScaleInternalToSI;
v_rel[2] = (v_ship[2] - v_earth[2]) * velocityScaleInternalToSI;
double v_rel_sq = (v_rel[0] * v_rel[0]) + (v_rel[1] * v_rel[1]) + (v_rel[2] * v_rel[2]);
// guard against divide by zero for norm
if (v_rel_sq < 1E-9)
{
return(accel);
}
double v_rel_mag = System.Math.Sqrt(v_rel_sq);
double a_mag = 0.5 * coeefDrag * crossSectionalArea * density * v_rel_sq / inertialMassKg;
// save the last live value for shipInfo etc.
if (isLiveState)
{
accel_last = a_mag;
}
// convert to GE scale
a_mag *= accelSItoGE;
// in the -ve direction of v_rel
v_rel[0] = -v_rel[0] / v_rel_mag;
v_rel[1] = -v_rel[1] / v_rel_mag;
v_rel[2] = -v_rel[2] / v_rel_mag;
accel[0] = a_mag * v_rel[0];
accel[1] = a_mag * v_rel[1];
accel[2] = a_mag * v_rel[2];
//if (logCount++ > LOG_INTERVAL) {
// logCount = 0;
// Debug.LogFormat("h={0} accel = ({1}, {2}, {3}) |a|={4} (m/s^2) -|v_rel|=({5},{6},{7}) v_rel = {8} m/s",
// h, accel[0], accel[1], accel[2], a_mag/accelSItoGE,
// v_rel[0], v_rel[1], v_rel[2], v_rel_mag);
//}
return(accel);
}
