Kepler elements maintains a time ordered list of OrbitUniversal segments. This allows a seqence of orbits around different bodies to be specified. For example, a free return trajectory around a moon would have: ellipse around Earth, hyperbola around moon, ellipse around Earth as three segements. By putting everything "on-rails" the scene can jump in time to any value requested without running NBody calculations for all the intermediate positions. More...

Inheritance diagram for KeplerSequence:

Classes
class	KeplerElement

Public Member Functions
delegate void	ElementStarted (OrbitUniversal orbitU)
	Optional callback to indicate when a specific element in the sequence starts.

delegate void	ReactivateCallback (NBody nbody)

delegate void	InactivateCallback (NBody nbody)

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.

OrbitUniversal	AppendElementRVT (Vector3d r0, Vector3d v0, double time, bool relativePos, NBody body, NBody centerBody, ElementStarted callback, Maneuver m=null)
	Add an element to the sequence using r0/v0/t0 initial conditions.

OrbitUniversal	NewOrbitSegment ()

void	AdvanceToNextSegment ()
	Force KS to go to the next element.

void	AppendElementExistingOrbitU (OrbitUniversal orbitU, ElementStarted callback)
	Add an element using an existing OrbitUniversal instance.

void	AppendReturnToGE (double time, NBody body)

void	AppendInactive (double time, InactivateCallback inactivateCallback, ReactivateCallback reactivateCallback)

void	Evolve (double physicsTime, GravityState gs, 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.

OrbitUniversal	GetCurrentOrbit ()
	Get the current OrbitUniversal for the orbit.

OrbitUniversal	GetOrbitAtIndex (int index)
	Get orbit at the specified index. If -1 use the last entry.

int	GetCurrentOrbitIndex ()
	Return the index of the current orbit sequence. (Used in the editor script for in-scene display)

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

void	SetNBody (NBody nbody)
	Not valid for a Kepler Sequence.

void	SetTimeoffset (double timeOffset)

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

Vector3	ApplyImpulse (Vector3 impulse)
	Apply the impulse to the current OrbitUniversal element.

bool	IsOnRails ()
	Usual case is that a KeplerSequence is on rails but can be a misconfiguration where the base OrbitUniversal is set to GE mode. In this case assume the OrbitUnversal config is intentional, warn about the misconfig and continue.

void	UpdatePositionAndVelocity (Vector3 pos, Vector3 vel)
	Set the position and velocity at the current time.

void	AddManeuver (Maneuver m)

void	AddManeuvers (List< Maneuver > maneuverList)
	Add orbit segments for each of the maneuvers. The maneuvers must have been created by transfer code that populated the fields: relativeTo, relativePos, relativeVel and time fields.

bool	RemoveManeuvers (List< Maneuver > maneuverList)
	Remove maneuvers from the Kepler sequence IF they have not started yet.

void	RemoveFutureSegments ()
	Remove all segments that occur after the current time.

void	RemoveSegmentsAfterTime (double time)
	Remove all segments after the specified time.

void	Reset ()
	Remove all previous and current segments. Used when a body is put back on rails after a period of NBody evolution. The on-rails code will explicitly add an orbitU.

void	CopyFrom (KeplerSequence copyFrom, bool retainActivateCallbacks=false, bool retainManeuverCallbacks=false)
	Make a copy of the KeplerSequence copyFrom.

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

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.

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.

Detailed Description

Kepler elements maintains a time ordered list of OrbitUniversal segments. This allows a seqence of orbits around different bodies to be specified. For example, a free return trajectory around a moon would have: ellipse around Earth, hyperbola around moon, ellipse around Earth as three segements. By putting everything "on-rails" the scene can jump in time to any value requested without running NBody calculations for all the intermediate positions.

On Init the KeplerSequence will automatically find and add the existing OrbitUniversal at the start of the list.

Note that this is NOT real physics since it is a series of two body evolutions and it is not what would really happen. It may be a good enough model for a game, depending on the importance of accuracy vs utility of jumping in time and getting results that do not vary based on numerical accuracy chosen for the GE.

The individual orbital elements are created as components and attached to a synthesized child object (this ensures the KeplerSequence can be unambigously attached to an NBody. This requires that the active body and center body for the sequence elements be set explicitly (they cannot be inferred).

Member Function Documentation

◆ AddManeuvers()

void KeplerSequence.AddManeuvers ( List< Maneuver > maneuverList )

Add orbit segments for each of the maneuvers. The maneuvers must have been created by transfer code that populated the fields: relativeTo, relativePos, relativeVel and time fields.

Parameters

list

◆ AdvanceToNextSegment()

void KeplerSequence.AdvanceToNextSegment ( )

Force KS to go to the next element.

This is hacky and is used in the case where a KS SetVelocityDouble is used by the auto-tester in the same flow where an orbit check will be done before a newly appended element at the current time becomes active.

◆ AppendElementExistingOrbitU()

void KeplerSequence.AppendElementExistingOrbitU	(	OrbitUniversal	orbitU,
		ElementStarted	callback
	)

Add an element using an existing OrbitUniversal instance.

Orbit elements must be added in increasing time order.

Parameters

orbitU
callback	(Optional) Method to call when sequence starts

◆ AppendElementRVT()

OrbitUniversal KeplerSequence.AppendElementRVT	(	Vector3d	r0,
		Vector3d	v0,
		double	time,
		bool	relativePos,
		NBody	body,
		NBody	centerBody,
		ElementStarted	callback,
		Maneuver	m = `null`
	)

Add an element to the sequence using r0/v0/t0 initial conditions.

Position and velocity are with respect to the center body (NOT world/physics space!).

Orbit segements must be added in increasing time order.

Parameters

r0
v0
time
relativePos
body
centerBody
callback	(Optional) Method to call when sequence starts

Returns

◆ ApplyImpulse()

Vector3 KeplerSequence.ApplyImpulse ( Vector3 impulse )

Apply the impulse to the current OrbitUniversal element.

This will break time-reversal because this change in impulse is not recorded.

Parameters

impulse

Returns

Implements IFixedOrbit.

◆ CopyFrom()

void KeplerSequence.CopyFrom	(	KeplerSequence	copyFrom,
		bool	retainActivateCallbacks = `false`,
		bool	retainManeuverCallbacks = `false`
	)

Make a copy of the KeplerSequence copyFrom.

Parameters

copyFrom

◆ DumpInfo()

string KeplerSequence.DumpInfo ( )

Create a string with info for display in GEConsole.

Returns

Implements IFixedOrbit.

◆ Evolve()

void KeplerSequence.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.

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

Implements IFixedOrbit.

◆ GetCenterNBody()

NBody KeplerSequence.GetCenterNBody ( )

Return the center NBody for the fixed orbit.

Returns

Implements IFixedOrbit.

◆ GetCurrentOrbit()

OrbitUniversal KeplerSequence.GetCurrentOrbit ( )

Get the current OrbitUniversal for the orbit.

Returns

◆ GetCurrentOrbitIndex()

int KeplerSequence.GetCurrentOrbitIndex ( )

Return the index of the current orbit sequence. (Used in the editor script for in-scene display)

Returns

◆ GetOrbitAtIndex()

OrbitUniversal KeplerSequence.GetOrbitAtIndex ( int index )

Get orbit at the specified index. If -1 use the last entry.

Parameters

index

Returns

◆ GEUpdate()

void KeplerSequence.GEUpdate ( GravityEngine ge )

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

Implements IFixedOrbit.

◆ InitNBody()

void KeplerSequence.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.

Parameters

physicalScale Physical scale.

Implements INbodyInit.

◆ IsOnRails()

bool KeplerSequence.IsOnRails ( )

Usual case is that a KeplerSequence is on rails but can be a misconfiguration where the base OrbitUniversal is set to GE mode. In this case assume the OrbitUnversal config is intentional, warn about the misconfig and continue.

Returns

Implements IFixedOrbit.

◆ Move()

void KeplerSequence.Move ( Vector3 position )

Handle dynamic origin shift.

Parameters

position

Implements IFixedOrbit.

◆ PreEvolve()

void KeplerSequence.PreEvolve	(	float	physicalScale,
		float	massScale
	)

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.

◆ RemoveManeuvers()

bool KeplerSequence.RemoveManeuvers ( List< Maneuver > maneuverList )

Remove maneuvers from the Kepler sequence IF they have not started yet.

If they have started or are in the past, leave in place and return an error.

Parameters

maneuverList

◆ RemoveSegmentsAfterTime()

void KeplerSequence.RemoveSegmentsAfterTime ( double time )

Remove all segments after the specified time.

Parameters

time

◆ SetNBody()

void KeplerSequence.SetNBody ( NBody nbody )

Not valid for a Kepler Sequence.

Parameters

nbody

Implements IFixedOrbit.

◆ UpdatePositionAndVelocity()

void KeplerSequence.UpdatePositionAndVelocity	(	Vector3	pos,
		Vector3	vel
	)

Set the position and velocity at the current time.

This will break time reversal since the change is not recorded.

Parameters

pos
vel

Implements IFixedOrbit.

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

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

Classes

Public Member Functions

Detailed Description

Member Function Documentation

◆ AddManeuvers()

◆ AdvanceToNextSegment()

◆ AppendElementExistingOrbitU()

◆ AppendElementRVT()

◆ ApplyImpulse()

◆ CopyFrom()

◆ DumpInfo()

◆ Evolve()

◆ GetCenterNBody()

◆ GetCurrentOrbit()

◆ GetCurrentOrbitIndex()

◆ GetOrbitAtIndex()

◆ GEUpdate()

◆ InitNBody()

◆ IsOnRails()

◆ Move()

◆ PreEvolve()

◆ RemoveManeuvers()

◆ RemoveSegmentsAfterTime()

◆ SetNBody()

◆ UpdatePositionAndVelocity()