A generic double precision orbit class. Can be used in place of OrbitEllipse and OrbitHyper. More...

Inheritance diagram for OrbitUniversal:

Public Types
enum	EvolveMode { GRAVITY_ENGINE , KEPLERS_EQN , SGP4_PROPAGATOR , PKEPLER_J2 }
	Mode for evolution; NBody simulation in GE or "on-rails" using Kepler equation.

enum	InputMode { DOUBLE , DOUBLE_ELLIPSE , ELLIPSE_MAJOR_AXIS_A , ELLIPSE_APOGEE_PERIGEE , ECC_PERIGEE , TWO_LINE_ELEMENT_SET }

Public Member Functions
virtual void	InitNBody (float physicalScale, float massScale)
	Inits the N body. Called prior to evolution starting. Allows NBody object to adjust its position and velocity prior to evolution beginning.

void	InitFromActiveNBody (NBody activeNbody, NBody center, EvolveMode mode)
	Use an active NBody that is live in GE to initialize an orbit.

void	InitFromJplEphemeris (string data)

void	InitCOEFromTLEData ()
	Init the classical orbital element (COE) from Celestrak two-line element (TLE) information.

string	TLEStartEpoch ()

void	Init ()

void	Reset ()
	Reset the OrbitPredictor init mode.

void	SetMajorAxisInspector (double a)
	For ellipses can specify size using major-axis. Typically used by editor script, but may have other uses.

double	GetMajorAxisInspector ()
	Get the major axis for the orbit using the inspector value (world units).

double	GetMajorAxis ()
	Get the Major Axis is internal physical units. If the orbit is an ellipse the major axis is valid. If the orbit is a hyperbola, then the value of p will be negative and there is no major axis value.

double	GetApogeeInspector ()
	Get the apogee (point of greatest distance from focus) for the orbit in Scaled units (e.g. ORBITAL). This is typically used in the inspector prior to the game starting.

double	GetApogee ()
	Determine the orbit apogee (apoapsis) is internal physics units.

double	GetSemiParam ()

SGP4toGE	GetSGP4ToGE ()

double	GetEnergy ()
	Compute a real-time value for the orbital energy based on (r,v)

double	GetPerigeeInspector ()
	Get the perigee (point of closest approach to the focus) for the orbit in Scaled units (e.g. ORBITAL). This is typically used in the inspector prior to the game starting.

double	GetPerigee ()
	Determine the orbit preigee (periapsis) is internal physics units.

void	SetSizeWithApogeePerigee (double apogee, double perigee)
	Set the size and eccentricity of the ellipse by using values for apogee and perigee. (To be precise really should call them apoapsis and periapsis, but more people will know apogee/perigee).

void	SetSizeWithEccPerigee (double ecc, double perigee)

void	SetOrbitPredictor (bool flag)

delegate void	SGP4ErrorCallback (OrbitUniversal ou, int error)
	In SGP4 propagation the satellite can decay to the point where it should not be propagated. Users may wish to trigger a callback on this event. This allows for a callback to be registered.

void	AddSGP4ErrorCallback (SGP4ErrorCallback errorCallback)
	Callback for when an SGP4 satellite decays.

double	GetMu ()

void	SetMu (double mu)
	Set the mass of the orbit system. This is intended for use when OrbitU is not attached to an NBody e.g. in the case of a DustOrbit.

void	InitMu ()
	Init the value of mu from the nbody elements. Typically used by OrbitPredictor.

NBody	GetNBody ()

Vector3d	GetAxis ()
	Get the normal vector to the orbital plane (normalized).

void	InitFromOrbitData (OrbitData od, double time)
	Initialize the Orbit from orbital elements contained in an OrbitData object.

void	CopyFromOrbitUniversal (OrbitUniversal fromOrbit)
	Init from another OrbitUniversal.

void	InitFromRVT (Vector3d r, Vector3d v, double time, NBody center, bool relativePos, bool updateState=false)
	Initialize the orbit using position, velocity and time.

void	SetDejitterCOE (bool value)

void	ReInitForOrbitPredictor (Vector3d r, Vector3d v, double time)
	OrbitPredictor does not need to do a full re-init, just use RV to set new COE.

OrbitUtils.OrbitElements.TypeOrbit	PredictedOrbitType ()
	When this OrbitU is being used as an orbit predictor report the last type that was determined by the RVtoCOE.

void	InitFromSolarBody (SolarBody sbody)
	Inits from solar body. This will always be an ellipse.

OrbitUtils.OrbitElements	GetPKeplerCOE ()

virtual void	ApplyScale (float scale)
	Interface to apply the scale to the distance parameter of an orbit.

virtual void	ApplyXZChange ()

virtual bool	IsOnRails ()
	Check if body is configured at scene start to be fixed. (Allows objects to be optionally configured as not fixed, to allow e.g. Kepler eqn vs initial velocity in OrbitEllipse)

virtual void	PreEvolve (float physicalScale, float massScale)
	Called for each NBody object prior to evolution beginning. Allows a chance to setup internal state.

virtual void	Evolve (double physicsTime, GravityState gravityState, ref double[] r_new, ref double[] v_new, bool isQuery=false)
	Evolve the NBody. Implementating method uses physics time and scale to compute the new position, placing it in r. Velocity is also updated so that GetVelocity() can request it if it is of interest.

virtual void	EvolveSGP4 (double physicsTime, GravityState gravityState, double[] r_new, double[] v_new, bool isQuery=false)
	Evolve using the Simplified General Pertubation propagator model V4.

void	SetSGP4BlendTime (double time)

void	LockAtTime (double lockTime)
	Use in On-Rails mode to lock an object at a specific time. Any evolve calls will not re-compute the position/velocity but instead leave them unchanged.

void	UnlockTime ()

Vector3d	GetLockedPosVel ()

double	GetPeriod ()

double	GetAngularVelocity ()

double	GetStartTime ()

void	GetRVT (ref Vector3d r0, ref Vector3d v0, ref double time0)
	Get the intial conditions for the orbit. R0 and V0 are always relative to the center body. If the center is not at (0,0,0) and/or moving, need to adjust values outside.

bool	RVT_Equal (ref Vector3d r0, ref Vector3d v0, ref double time0, double tol)
	Utility function (used by e.g. OrbitPredictor) to see if the orbit initial conditions have changed. Used to determine when an OP needs to recompute the orbit in KEPLER mode.

void	GetRVTAbsolute (ref Vector3d r0, ref Vector3d v0, ref double time0)

void	GEUpdate (GravityEngine ge)
	Perform and update of the world game object position and velocity based on the internal state.

void	Move (Vector3 position)
	Move in response to a GE.MoveAll() call. (Not called from outside GE).

void	SetNBody (NBody nbody)
	Set the NBody that the orbit element will evolve. This is not commonly used, since the NBody is typically attached to the same game object as the FixedOrbit. The exception is when fixed orbit segments are part of a KeplerSequence (patched-conic evolution).

Vector3[]	OrbitPositions (int numPoints, Vector3 centerPos, bool doSceneMapping)

Vector3[]	OrbitPositions (int numPoints, Vector3 centerPos, bool doSceneMapping, float hyperRadius)

Vector3	PositionForPhase (float phaseDeg)
	Get the position for the specified phase in physics co-ordinates.

Vector3	VelocityForPhaseRelative (float phaseDeg)

Vector3	VelocityForPosition (Vector3 position)
	Given a position on the orbit (or a position that is used to establish a phase wrt the center) determine the velocity vector at that point on the orbit.

bool	CanApplyImpulse ()

NBody	GetCenterNBody ()
	Return the center NBody for the fixed orbit.

void	UpdatePositionAndVelocity (Vector3 pos, Vector3 vel)
	Set a new start position for orbit evolution with respect to the current center object.

void	SetNewCenter (NBody newCenter)
	Set a new center object. Used when doing Kepler ("on-rails") evolution and the object enters the sphere of influence of a new body. The inital conditions (r0,v0, t0) are updated to be with respect to the new center object allowing Kepler evolution wrt the new center.

void	ChangeEvolveMode (EvolveMode newMode)
	Change the evolve mode between KEPLER and GRAVITY_ENGINE. i.e. go from off-rails to on-rails.

Vector3	ApplyImpulse (Vector3 impulse)
	Apply an impulse to change the on-rails evolution (Kepler or SGP4). OrbitUniversal supports seamless changes from ellipse to parabola to hyperbola. This updates the initial conditions and start time (r0, v0, time0)

double	TimeOfFlight (Vector3d r0, Vector3d r1)
	Determine the time of flight in physics time units (GE internal time) that it takes for the body in orbit to go from relative position r0 to position r1.

double	TimeOfFlightEllipse (Vector3d r0, Vector3d r1)
	Find the time of flight from position r0 to r1 when the orbit is elliptical.

bool	IsCircular ()

Quaternion	GetConicOrientation ()

Vector3[]	HyperSegmentSymmetric (int numPoints, Vector3 centerPos, float radiusOrZero, bool doSceneMapping)
	Calculate points suitable for a line renderer that show a segment of the hyperbola for a specified radius with respect to the center.

Vector3[]	EllipseSegment (int numPoints, Vector3 centerPos, Vector3 pos, Vector3 destPoint, bool shortPath)
	Generate the points for an ellipse segment given the start and end positions. If shortPath then the short path between the points will be shown, otherwise the long way around.

Vector3[]	EllipseSegmentProRetro (int numPoints, Vector3 centerPos, Vector3 pos, Vector3 destPoint, bool retrograde)
	Generate the points for an ellipse segment given the start and end positions.

virtual string	DumpInfo ()
	Create a string with info for display in GEConsole.

Vector3	GetPositionForThetaRadians (float thetaRadians, Vector3 centerPos)
	Determine orbit position in physics space (with rotation and center offset) for the specified angle in the orbit (in radians)

Vector3d	GetPositionDForThetaRadians (double thetaRadians, bool relative)
	Determine orbit position in physics space (with rotation and center offset) for the specified angle in the orbit (in radians)

Vector3d	GetVelocityDForThetaRadians (double theta, bool relative)

Vector3[]	GetPositionsForRadius (double radius, Vector3 centerPos)
	Get the positions where the orbit is at a specified radius. In general there are two. The result is positions in world space. These can then be used in e.g. TimeOfFlight.

float	GetPhaseDegForRadius (double radius)
	Get the phase for the specified radius/altitude.

OrbitUtils.OrbitElements	GetCurrentOrbitalElements ()
	Get the current orbital elements using the live position and velocity from GE.

double	GetCurrentPhase ()
	Get the current phase (degrees) of the body based on the position and velocity retreived from GE.

Vector3[]	GetPositionsForRadius (double radius)
	Get the positions where the orbit is at a specified radius. In general there are two. The result is positions in world space. These can then be used in e.g. TimeOfFlight.

void	SetPositionDouble (Vector3d pos)

void	InitNBody (float physicalScale, float massScale)
	Inits the N body. Called prior to evolution starting. Allows NBody object to adjust its position and velocity prior to evolution beginning.

bool	IsOnRails ()
	Check if body is configured at scene start to be fixed. (Allows objects to be optionally configured as not fixed, to allow e.g. Kepler eqn vs initial velocity in OrbitEllipse)

void	PreEvolve (float physicalScale, float massScale)
	Called for each NBody object prior to evolution beginning. Allows a chance to setup internal state.

void	Evolve (double physicsTime, GravityState gravityState, ref double[] r, ref double[] v, bool isQuery=false)
	Evolve the NBody. Implementating method uses physics time and scale to compute the new position, placing it in r. Velocity is also updated so that GetVelocity() can request it if it is of interest.

void	GEUpdate (GravityEngine ge)
	Perform and update of the world game object position and velocity based on the internal state.

void	Move (Vector3 position)
	Handle dynamic origin shift.

void	SetNBody (NBody nbody)
	Set the NBody that the orbit element will evolve. This is not commonly used, since the NBody is typically attached to the same game object as the FixedOrbit. The exception is when fixed orbit segments are part of a KeplerSequence (patched-conic evolution).

Vector3	ApplyImpulse (Vector3 impulse)
	ApplyImpulse in Kepler mode. (Currently only OrbitUniversal does this)

NBody	GetCenterNBody ()
	Return the center NBody for the fixed orbit.

void	UpdatePositionAndVelocity (Vector3 pos, Vector3 vel)
	Update the position and velocity of the object in the orbit.

string	DumpInfo ()
	Create a string with info for display in GEConsole.

Vector3[]	OrbitPositions (int numPoints, Vector3 centerPos, bool doSceneMapping)

void	ApplyScale (float scale)
	Interface to apply the scale to the distance parameter of an orbit.

void	ApplyXZChange ()

Public Attributes
EvolveMode	evolveMode

double	p = 10.0

double	p_inspector = 10.0
	Value of semi-parameter p from inspector (i.e. in GE selected units such as ORBITAL or SOLAR)

double	eccentricity

double	inclination
	inclinataion in degrees (0..180)

double	omega_uc
	Omega in degress (0..360)

double	omega_lc
	omega in degress (0..360)

double	phase = 0
	Phase in orbit in degrees.

double	sgp4_no

double	sgp4_bstar

double	pkepler_ndot = 0

double	pkepler_nddot = 0

NBody	centerNbody
	Object influencing this bodies motion.

InputMode	inputMode = InputMode.DOUBLE

string	jplEphemeris = ""

string	tleName = ""

string	tleLine1 =""

string	tleLine2 =""

bool	dejitterCOE = false

	Vector3d

Protected Member Functions
void	CalculateRotation ()

Protected Attributes
Quaternion	conic_orientation

GravityEngine	ge

Detailed Description

A generic double precision orbit class. Can be used in place of OrbitEllipse and OrbitHyper.

Maintains all orbital elements in double precision in internal GE units.

Supports two evolve modes: GRAVITY_ENGINE: Set initial velocity and poistion based on orbital elements and then let GE integrators move the body as time evolves.

KEPLER: Use Kepler's equation (position, velocity as a function of time) to determine when the body is each GE update. GE will still use the mass of this body to influence other bodies in the scene.

Arbitrary nesting of these modes is expected. (i.e. Kepler motion of a moon, around a GE planet in orbit around a Sun etc.)

Since the semi-major axis (a) can change sign as eccentricy changes, specify the scale of the orbit with p (semi-latus rectum).

Member Function Documentation

◆ AddSGP4ErrorCallback()

void OrbitUniversal.AddSGP4ErrorCallback ( SGP4ErrorCallback errorCallback )

Callback for when an SGP4 satellite decays.

Warning: This is called from within the GE physics loop. Do not direcly call RemoveBody() while inside this code!

Parameters

errorCallback

◆ ApplyImpulse()

Vector3 OrbitUniversal.ApplyImpulse ( Vector3 impulse )

Apply an impulse to change the on-rails evolution (Kepler or SGP4). OrbitUniversal supports seamless changes from ellipse to parabola to hyperbola. This updates the initial conditions and start time (r0, v0, time0)

This method is usually called from GravityEngine ApplyImpulse(). Not commonly called from game code.

Parameters

impulse Adjusted Impulse

Implements IFixedOrbit.

◆ ApplyScale()

virtual void OrbitUniversal.ApplyScale ( float scale )

virtual

Interface to apply the scale to the distance parameter of an orbit.

Parameters

scale Scale.

Implements IOrbitScalable.

Reimplemented in BinaryOrbit.

◆ ApplyXZChange()

virtual void OrbitUniversal.ApplyXZChange ( )

virtual

Implements IOrbitScalable.

◆ ChangeEvolveMode()

void OrbitUniversal.ChangeEvolveMode ( EvolveMode newMode )

Change the evolve mode between KEPLER and GRAVITY_ENGINE. i.e. go from off-rails to on-rails.

Parameters

newMode

◆ CopyFromOrbitUniversal()

void OrbitUniversal.CopyFromOrbitUniversal ( OrbitUniversal fromOrbit )

Init from another OrbitUniversal.

Parameters

od

◆ DumpInfo()

virtual string OrbitUniversal.DumpInfo ( )

virtual

Create a string with info for display in GEConsole.

Returns

Implements IFixedOrbit.

Reimplemented in BinaryOrbit.

◆ EllipseSegment()

Vector3[] OrbitUniversal.EllipseSegment	(	int	numPoints,
		Vector3	centerPos,
		Vector3	pos,
		Vector3	destPoint,
		bool	shortPath
	)

Generate the points for an ellipse segment given the start and end positions. If shortPath then the short path between the points will be shown, otherwise the long way around.

The points are used to determine an angle from the main axis of the ellipse and although they should be on the ellipse for best results, the code will do it's best if they are not.

Parameters

numPoints
centerPos
pos
destPoint
shortPath

Returns

◆ EllipseSegmentProRetro()

Vector3[] OrbitUniversal.EllipseSegmentProRetro	(	int	numPoints,
		Vector3	centerPos,
		Vector3	pos,
		Vector3	destPoint,
		bool	retrograde
	)

Generate the points for an ellipse segment given the start and end positions.

The points are used to determine an angle from the main axis of the ellipse and although they should be on the ellipse for best results, the code will do it's best if they are not.

Parameters

numPoints
centerPos
pos
destPoint
retrograde

Returns

◆ Evolve()

virtual void OrbitUniversal.Evolve	(	double	physicsTime,
		GravityState	gravityState,
		ref double[]	r,
		ref double[]	v,
		bool	isQuery = `false`
	)

virtual

Evolve the NBody. Implementating method uses physics time and scale to compute the new position, placing it in r. Velocity is also updated so that GetVelocity() can request it if it is of interest.

Parameters

physicsTime	Current Physics time.
physicalScale	Physical scale.
r	Position in physics space (x, y, z). OUTPUT by the method
v	Velocity in physics space (x, y, z). OUTPUT by the method
isQuery	Request is a query and should not change state or do callbacks

The SGP4 algorithm will not accurately reproduce the position and velocity for the COE elements in the TLE at time 0. This is due to the fact that some of the COE secular pertubations modifiy the COE values even when time has not evolved.

When GE wants to reset an SGP4 evolution e.g. after an impulse/maneuver it is important that the satellite does not suddenly jump to a new position or velocity. There is no way to preadjust the COE values so that with secular variations at t=0 the algorithm gives the required r. The solution is to start position/velocity calculations at t=0 using the TLE COE values and then to "Lerp" over to the secular values. The timescale for this lerping is a matter of choice. It can be fixed as an absolute time or can be expressed as a factor of the orbital period of the satellite. This "Lerp setting" is selected globally in the GE advanced foldout.

Implements IFixedOrbit.

Reimplemented in BinaryOrbit.

◆ EvolveSGP4()

virtual void OrbitUniversal.EvolveSGP4	(	double	physicsTime,
		GravityState	gravityState,
		double[]	r_new,
		double[]	v_new,
		bool	isQuery = `false`
	)

virtual

Evolve using the Simplified General Pertubation propagator model V4.

See: https://en.wikipedia.org/wiki/Simplified_perturbations_models

Parameters

physicsTime
gravityState
r_new
v_new

◆ GetApogee()

double OrbitUniversal.GetApogee ( )

Determine the orbit apogee (apoapsis) is internal physics units.

Typically used for an ellipse. For a hyperbola will be a negative number.

Returns: apogee value in internal physics units

◆ GetApogeeInspector()

double OrbitUniversal.GetApogeeInspector ( )

Get the apogee (point of greatest distance from focus) for the orbit in Scaled units (e.g. ORBITAL). This is typically used in the inspector prior to the game starting.

Typically used for an ellipse. For a hyperbola will be a negative number.

Returns

◆ GetAxis()

Vector3d OrbitUniversal.GetAxis ( )

Get the normal vector to the orbital plane (normalized).

Returns

◆ GetCenterNBody()

NBody OrbitUniversal.GetCenterNBody ( )

Return the center NBody for the fixed orbit.

Returns

Implements IFixedOrbit.

◆ GetCurrentOrbitalElements()

OrbitUtils.OrbitElements OrbitUniversal.GetCurrentOrbitalElements ( )

Get the current orbital elements using the live position and velocity from GE.

Returns

◆ GetCurrentPhase()

double OrbitUniversal.GetCurrentPhase ( )

Get the current phase (degrees) of the body based on the position and velocity retreived from GE.

Returns

◆ GetEnergy()

double OrbitUniversal.GetEnergy ( )

Compute a real-time value for the orbital energy based on (r,v)

Returns

◆ GetMajorAxis()

double OrbitUniversal.GetMajorAxis ( )

Get the Major Axis is internal physical units. If the orbit is an ellipse the major axis is valid. If the orbit is a hyperbola, then the value of p will be negative and there is no major axis value.

Returns

◆ GetMajorAxisInspector()

double OrbitUniversal.GetMajorAxisInspector ( )

Get the major axis for the orbit using the inspector value (world units).

for a hyperbola this is negative
for a parabola this is NaN

Returns

◆ GetPerigee()

double OrbitUniversal.GetPerigee ( )

Determine the orbit preigee (periapsis) is internal physics units.

Returns: perigee value in internal physics units

◆ GetPerigeeInspector()

double OrbitUniversal.GetPerigeeInspector ( )

Get the perigee (point of closest approach to the focus) for the orbit in Scaled units (e.g. ORBITAL). This is typically used in the inspector prior to the game starting.

Valid for all orbit types.

Returns

◆ GetPhaseDegForRadius()

float OrbitUniversal.GetPhaseDegForRadius ( double radius )

Get the phase for the specified radius/altitude.

In the case of an ellipse if the altitute larger/smaller than those allowed just return the max. An ellipse will have two values that match the altitude. To get the alternative one use (360 - phase).

A circular orbit will return a phase of zero for any altitude.

Parameters

radius

Returns

◆ GetPositionDForThetaRadians()

Vector3d OrbitUniversal.GetPositionDForThetaRadians	(	double	thetaRadians,
		bool	relative
	)

Determine orbit position in physics space (with rotation and center offset) for the specified angle in the orbit (in radians)

Common code works for ellipse and hyperbola, but not a parabola. Nudge a parabola into hyperbola

Parameters

thetaRadians
relative

Returns

◆ GetPositionForThetaRadians()

Vector3 OrbitUniversal.GetPositionForThetaRadians	(	float	thetaRadians,
		Vector3	centerPos
	)

Determine orbit position in physics space (with rotation and center offset) for the specified angle in the orbit (in radians)

Common code works for ellipse and hyperbola, but not a parabola. Nudge a parabola into hyperbola

Parameters

thetaRadians
centerPos

Returns

◆ GetPositionsForRadius() [1/2]

Vector3[] OrbitUniversal.GetPositionsForRadius ( double radius )

Get the positions where the orbit is at a specified radius. In general there are two. The result is positions in world space. These can then be used in e.g. TimeOfFlight.

Use the general equation for hyperbola and ellipse and nudge a parabola into a hyperbola.

Parameters

radius

Returns

◆ GetPositionsForRadius() [2/2]

Vector3[] OrbitUniversal.GetPositionsForRadius	(	double	radius,
		Vector3	centerPos
	)

Get the positions where the orbit is at a specified radius. In general there are two. The result is positions in world space. These can then be used in e.g. TimeOfFlight.

Use the general equation for hyperbola and ellipse and nudge a parabola into a hyperbola.

Parameters

radius

Returns

◆ GetRVT()

void OrbitUniversal.GetRVT	(	ref Vector3d	r0,
		ref Vector3d	v0,
		ref double	time0
	)

Get the intial conditions for the orbit. R0 and V0 are always relative to the center body. If the center is not at (0,0,0) and/or moving, need to adjust values outside.

These value are always available (even if orbitU was not inited with InitRVT).

Parameters

r0
v0
time0

◆ GEUpdate()

void OrbitUniversal.GEUpdate ( GravityEngine ge )

Perform and update of the world game object position and velocity based on the internal state.

Implements IFixedOrbit.

◆ HyperSegmentSymmetric()

Vector3[] OrbitUniversal.HyperSegmentSymmetric	(	int	numPoints,
		Vector3	centerPos,
		float	radiusOrZero,
		bool	doSceneMapping
	)

Calculate points suitable for a line renderer that show a segment of the hyperbola for a specified radius with respect to the center.

Parameters

numPoints
centerPos
radius
doSceneMapping

Returns

◆ InitCOEFromTLEData()

void OrbitUniversal.InitCOEFromTLEData ( )

Init the classical orbital element (COE) from Celestrak two-line element (TLE) information.

The TLE info describes the orbital parameters and position at a time reference embedded in the TLE.

It is necessary to advance the position and orbital elements to the start time (as a Julian day from GE). This is done using the SGP4 propagator.

The time since GE started is then evolved using a standard GE orbit propagator.

◆ InitFromActiveNBody()

void OrbitUniversal.InitFromActiveNBody	(	NBody	activeNbody,
		NBody	center,
		EvolveMode	mode
	)

Use an active NBody that is live in GE to initialize an orbit.

Can be used in Kepler mode to determine the future position of the object by subsequently calling Evolve(). Used by LambertPhasing to propogate the target for the time required for the transfer.

◆ InitFromOrbitData()

void OrbitUniversal.InitFromOrbitData	(	OrbitData	od,
		double	time
	)

Initialize the Orbit from orbital elements contained in an OrbitData object.

Parameters

od

◆ InitFromRVT()

void OrbitUniversal.InitFromRVT	(	Vector3d	r,
		Vector3d	v,
		double	time,
		NBody	center,
		bool	relativePos,
		bool	updateState = `false`
	)

Initialize the orbit using position, velocity and time.

Position and velocity are relative to the center object. (This is because when eg. adding a segement arount a moon in free return calculations cannot assume we mean the current position of the center).

Parameters

r	relative position wrt center
v	relative velocity wrt center
time
center

◆ InitFromSolarBody()

void OrbitUniversal.InitFromSolarBody ( SolarBody sbody )

Inits from solar body. This will always be an ellipse.

Parameters

sbody Sbody.

◆ InitNBody()

virtual void OrbitUniversal.InitNBody	(	float	physicalScale,
		float	massScale
	)

virtual

Inits the N body. Called prior to evolution starting. Allows NBody object to adjust its position and velocity prior to evolution beginning.

Parameters

physicalScale Physical scale.

Implements INbodyInit.

Reimplemented in BinaryOrbit.

◆ IsOnRails()

virtual bool OrbitUniversal.IsOnRails ( )

virtual

Check if body is configured at scene start to be fixed. (Allows objects to be optionally configured as not fixed, to allow e.g. Kepler eqn vs initial velocity in OrbitEllipse)

Returns: true if this instance is fixed; otherwise, false.

Implements IFixedOrbit.

Reimplemented in BinaryOrbit.

◆ LockAtTime()

void OrbitUniversal.LockAtTime ( double lockTime )

Use in On-Rails mode to lock an object at a specific time. Any evolve calls will not re-compute the position/velocity but instead leave them unchanged.

This will be applied to the orbit for the world state. If trajectory prediction is being used this will result in the locked times being returned for the trajectory - this will be wrong.

Do not use when trajectory prediction is enabled.

Parameters

lockTime

◆ Move()

void OrbitUniversal.Move ( Vector3 position )

Move in response to a GE.MoveAll() call. (Not called from outside GE).

Since the next time Evolve() is called it will get a new center, no need to change the position here.

Parameters

position

Implements IFixedOrbit.

◆ OrbitPositions()

Vector3[] OrbitUniversal.OrbitPositions	(	int	numPoints,
		Vector3	centerPos,
		bool	doSceneMapping
	)

Implements IOrbitPositions.

◆ PositionForPhase()

Vector3 OrbitUniversal.PositionForPhase ( float phaseDeg )

Get the position for the specified phase in physics co-ordinates.

(If map to scene is being used it up to the caller to do the conversion using ge.MapToScene() )

Parameters

phaseDeg

Returns

◆ PredictedOrbitType()

OrbitUtils.OrbitElements.TypeOrbit OrbitUniversal.PredictedOrbitType ( )

When this OrbitU is being used as an orbit predictor report the last type that was determined by the RVtoCOE.

Returns

◆ PreEvolve()

virtual void OrbitUniversal.PreEvolve	(	float	physicalScale,
		float	massScale
	)

virtual

Called for each NBody object prior to evolution beginning. Allows a chance to setup internal state.

Parameters

physicalScale	Physical scale.
massScale	Mass scale.

Implements IFixedOrbit.

Reimplemented in BinaryOrbit.

◆ ReInitForOrbitPredictor()

void OrbitUniversal.ReInitForOrbitPredictor	(	Vector3d	r,
		Vector3d	v,
		double	time
	)

OrbitPredictor does not need to do a full re-init, just use RV to set new COE.

Parameters

r
v
time

◆ Reset()

void OrbitUniversal.Reset ( )

Reset the OrbitPredictor init mode.

Current use case is test code that re-uses OUs. Some maneuvers may have set this.

◆ RVT_Equal()

bool OrbitUniversal.RVT_Equal	(	ref Vector3d	r0,
		ref Vector3d	v0,
		ref double	time0,
		double	tol
	)

Utility function (used by e.g. OrbitPredictor) to see if the orbit initial conditions have changed. Used to determine when an OP needs to recompute the orbit in KEPLER mode.

Parameters

r0
v0
time0
tol

Returns

◆ SetMajorAxisInspector()

void OrbitUniversal.SetMajorAxisInspector ( double a )

For ellipses can specify size using major-axis. Typically used by editor script, but may have other uses.

Parameters

a

◆ SetMu()

void OrbitUniversal.SetMu ( double mu )

Set the mass of the orbit system. This is intended for use when OrbitU is not attached to an NBody e.g. in the case of a DustOrbit.

Normally mu is determined correctly by an Init() call without recorse to this function.

Parameters

mu

◆ SetNBody()

void OrbitUniversal.SetNBody ( NBody nbody )

Set the NBody that the orbit element will evolve. This is not commonly used, since the NBody is typically attached to the same game object as the FixedOrbit. The exception is when fixed orbit segments are part of a KeplerSequence (patched-conic evolution).

Parameters

nbody

Implements IFixedOrbit.

◆ SetNewCenter()

void OrbitUniversal.SetNewCenter ( NBody newCenter )

Set a new center object. Used when doing Kepler ("on-rails") evolution and the object enters the sphere of influence of a new body. The inital conditions (r0,v0, t0) are updated to be with respect to the new center object allowing Kepler evolution wrt the new center.

Parameters

newCenter

◆ SetSizeWithApogeePerigee()

void OrbitUniversal.SetSizeWithApogeePerigee	(	double	apogee,
		double	perigee
	)

Set the size and eccentricity of the ellipse by using values for apogee and perigee. (To be precise really should call them apoapsis and periapsis, but more people will know apogee/perigee).

Typically only used for ellipses (but can work for hyperbolas) by the Editor script for this component.

Values provided are in GE scaled units (e.g. ORBITAL)

Parameters

apogee
perigee

◆ SGP4ErrorCallback()

delegate void OrbitUniversal.SGP4ErrorCallback	(	OrbitUniversal	ou,
		int	error
	)

In SGP4 propagation the satellite can decay to the point where it should not be propagated. Users may wish to trigger a callback on this event. This allows for a callback to be registered.

Parameters

ou

◆ TimeOfFlight()

double OrbitUniversal.TimeOfFlight	(	Vector3d	r0,
		Vector3d	r1
	)

Determine the time of flight in physics time units (GE internal time) that it takes for the body in orbit to go from relative position r0 to position r1.

Parameters

r0	from relative position (assumes center is (0,0,0)
r1	to relative position

Returns: time to travel from r0 to r1 in GE time

◆ TimeOfFlightEllipse()

double OrbitUniversal.TimeOfFlightEllipse	(	Vector3d	r0,
		Vector3d	r1
	)

Find the time of flight from position r0 to r1 when the orbit is elliptical.

Will issue a warning and return 0 when the orbit in not elliptical.

Parameters

r0
r1

Returns

◆ UpdatePositionAndVelocity()

void OrbitUniversal.UpdatePositionAndVelocity	(	Vector3	pos,
		Vector3	vel
	)

Set a new start position for orbit evolution with respect to the current center object.

Parameters

pos
vel

Implements IFixedOrbit.

◆ VelocityForPhaseRelative()

Vector3 OrbitUniversal.VelocityForPhaseRelative ( float phaseDeg )

Uses Vallado, Algorithm 10 for (x,y) plane and then rotates into place

◆ VelocityForPosition()

Vector3 OrbitUniversal.VelocityForPosition ( Vector3 position )

Given a position on the orbit (or a position that is used to establish a phase wrt the center) determine the velocity vector at that point on the orbit.

Parameters

position

Returns

Member Data Documentation

◆ p

double OrbitUniversal.p = 10.0

semi-parameter that defines orbit size in GE internal units. For a universal orbit p is needed. See SetMajorAxis() if a is needed.

The documentation for this class was generated from the following file:

C:/Users/musgr/Documents/Unity/gravityengine/Assets/GravityEngine/Scripts/Orbits/OrbitUniversal.cs

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ AddSGP4ErrorCallback()

◆ ApplyImpulse()

◆ ApplyScale()

◆ ApplyXZChange()

◆ ChangeEvolveMode()

◆ CopyFromOrbitUniversal()

◆ DumpInfo()

◆ EllipseSegment()

◆ EllipseSegmentProRetro()

◆ Evolve()

◆ EvolveSGP4()

◆ GetApogee()

◆ GetApogeeInspector()

◆ GetAxis()

◆ GetCenterNBody()

◆ GetCurrentOrbitalElements()

◆ GetCurrentPhase()

◆ GetEnergy()

◆ GetMajorAxis()

◆ GetMajorAxisInspector()

◆ GetPerigee()

◆ GetPerigeeInspector()

◆ GetPhaseDegForRadius()

◆ GetPositionDForThetaRadians()

◆ GetPositionForThetaRadians()

◆ GetPositionsForRadius() [1/2]

◆ GetPositionsForRadius() [2/2]

◆ GetRVT()

◆ GEUpdate()

◆ HyperSegmentSymmetric()

◆ InitCOEFromTLEData()

◆ InitFromActiveNBody()

◆ InitFromOrbitData()

◆ InitFromRVT()

◆ InitFromSolarBody()

◆ InitNBody()

◆ IsOnRails()

◆ LockAtTime()

◆ Move()

◆ OrbitPositions()

◆ PositionForPhase()

◆ PredictedOrbitType()

◆ PreEvolve()

◆ ReInitForOrbitPredictor()

◆ Reset()

◆ RVT_Equal()

◆ SetMajorAxisInspector()

◆ SetMu()

◆ SetNBody()

◆ SetNewCenter()

◆ SetSizeWithApogeePerigee()

◆ SGP4ErrorCallback()

◆ TimeOfFlight()

◆ TimeOfFlightEllipse()

◆ UpdatePositionAndVelocity()

◆ VelocityForPhaseRelative()

◆ VelocityForPosition()

Member Data Documentation

◆ p