OrbitData Class Reference

Orbit data. Hold the traditional orbit parameters for an elliptic/hyperbolic orbit. More...

Public Member Functions
	OrbitData (float a, float e, float i, float omega_uc, float omega_lc, float phase)
	OrbitData (OrbitData od)
	OrbitData (OrbitEllipse orbitEllipse)
	Construct an orbit data routine from an existing orbit ellipse by copying the orbital elements.
	OrbitData (OrbitUniversal orbitU)
	Construct an orbit data set using the OrbitUniversal attached to the OrbitPredictor on the body.
void	SetOrbitForVelocity (NBody forNbody, NBody aroundNBody, Vector3 velocity)
	Computes the orbit parameters for a specified velocity with respect to a central body. This method assumes the orbit is not a Kepler-mode orbit ellipse. If it is (or not sure) then use SetOrbit() below.
void	SetOrbitForVelocity (NBody forNbody, NBody aroundNBody)
	Computes the orbit parameters for a specified velocity (from NBody) with respect to a central body. This method assumes the orbit is not a Kepler-mode orbit ellipse. If it is (or not sure) then use SetOrbit() below.
void	SetOrbit (NBody forNbody, NBody aroundNBody)
	SetOrbit Determine orbit params from an attached orbit component (if Kepler) otherwise use the velocity to determine the orbit.
bool	IsCircular ()
Vector3d	GetAxis ()
	Compute the axis of the orbit by taking r x v at a specific phase and normalizing.
double	GetOmegaAngular ()
	Get the angular velocity in rad/time.
float	GetCircPhase ()
	Convenience method to get the phase assuming the orbit is circular. Useful for e.g. HohmannGeneral algorithms that assume the orbit is a perfect circle.
void	CalcTau (Vector3 r, Vector3 v)
	Determine the time to periapsis in physics time.
string	LogString ()
Vector3	GetPhysicsPositionforEllipse (float phaseDeg)
	Get the absolute physics position for a specified phase for the ellipse defined by this OrbitData.
Vector3	GetPhysicsPositionforEllipseRelative (float phaseDeg)
	Get position in the ellipse relative to the center body.
float	GetPhaseDegForRadius (double radius)
	Get the phase for the specified radius/altitude.
Vector3	GetPhysicsVelocityForEllipse (float phaseDeg)
	Determine velocity in physics units at the indicated phase angle (in degrees)
Vector3	GetPhysicsVelocity (float phaseDeg)
	Determine velocity in physics units at the indicated phase angle (in degrees)

Public Attributes
float	ecc
	eccentricity (0..1, 0=circle, 1=linear)
Vector3d	ecc_vec
	eccentricity vector (direction to point of closest approach when e != 0)
float	a = 10f
	semi-major axis - based on paramBy user can specify a OR p. a = p/(1-ecc)
float	perihelion
	perihelion
float	omega_uc
	"longitude of ascending node" - angle from x-axis to line from focus to pericenter
float	omega_lc
	"argument of perienter" - angle from ascending node to pericenter
float	inclination
	inclination (degrees!)
float	phase
	initial TRUE anomoly (angle wrt line from focus to closest approach)
float	period
	period of orbit in game time (uses GravityScalar.GameSecToWorldTime for world units)
float	tau
	time to periapsis (point of closest approach) in game seconds (use GravityScalar.GameSecToWorldTime for world units)
float	r_initial = 10f
	Hyperbola - initial distance from focus.
NBody	centralMass
NBody	nbody
float	mu
	Scaled mass of central body.

Static Public Attributes
const float	OD_ZERO_LIMIT = 0.001f

Detailed Description

Orbit data. Hold the traditional orbit parameters for an elliptic/hyperbolic orbit.

Provide utility methods to derive the orbit parameters from the position, velocity and centerBody of an NBody object pair. This orbit prediction is based only on the two bodies (and assumes the central body mass dominates) - the influence of other bodies in the scene may result in an actual path that is different from the predicted path.

Constructor & Destructor Documentation

OrbitData() [1/2]

OrbitData.OrbitData

(

OrbitEllipse

orbitEllipse

)

Construct an orbit data routine from an existing orbit ellipse by copying the orbital elements.

Parameters

orbitEllipse

OrbitData() [2/2]

OrbitData.OrbitData

(

OrbitUniversal

orbitU

)

Construct an orbit data set using the OrbitUniversal attached to the OrbitPredictor on the body.

This is not used with the OrbitUniversal attached to the NBody, that only provides the initial orbit info, not the live orbit info.

Parameters

orbitU

Member Function Documentation

CalcTau()

void OrbitData.CalcTau	(	Vector3	r,
		Vector3	v
	)

Determine the time to periapsis in physics time.

Parameters

r
v

GetAxis()

Vector3d OrbitData.GetAxis

(

)

Compute the axis of the orbit by taking r x v at a specific phase and normalizing.

Returns

GetCircPhase()

float OrbitData.GetCircPhase

(

)

Convenience method to get the phase assuming the orbit is circular. Useful for e.g. HohmannGeneral algorithms that assume the orbit is a perfect circle.

Returns

GetOmegaAngular()

double OrbitData.GetOmegaAngular

(

)

Get the angular velocity in rad/time.

Returns

GetPhaseDegForRadius()

float OrbitData.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

GetPhysicsPositionforEllipse()

Vector3 OrbitData.GetPhysicsPositionforEllipse

(

float

phaseDeg

)

Get the absolute physics position for a specified phase for the ellipse defined by this OrbitData.

Parameters

phaseDeg

Returns

GetPhysicsPositionforEllipseRelative()

Vector3 OrbitData.GetPhysicsPositionforEllipseRelative

(

float

phaseDeg

)

Get position in the ellipse relative to the center body.

Parameters

phaseDeg

Returns

GetPhysicsVelocity()

Vector3 OrbitData.GetPhysicsVelocity

(

float

phaseDeg

)

Determine velocity in physics units at the indicated phase angle (in degrees)

Parameters

phaseDeg

Returns

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

GetPhysicsVelocityForEllipse()

Vector3 OrbitData.GetPhysicsVelocityForEllipse

(

float

phaseDeg

)

Determine velocity in physics units at the indicated phase angle (in degrees)

Parameters

phaseDeg

Returns

SetOrbit()

void OrbitData.SetOrbit	(	NBody	forNbody,
		NBody	aroundNBody
	)

SetOrbit Determine orbit params from an attached orbit component (if Kepler) otherwise use the velocity to determine the orbit.

Parameters

forNbody
aroundNBody

SetOrbitForVelocity() [1/2]

void OrbitData.SetOrbitForVelocity	(	NBody	forNbody,
		NBody	aroundNBody
	)

Computes the orbit parameters for a specified velocity (from NBody) with respect to a central body. This method assumes the orbit is not a Kepler-mode orbit ellipse. If it is (or not sure) then use SetOrbit() below.

Parameters

forNbody
aroundNBody

SetOrbitForVelocity() [2/2]

void OrbitData.SetOrbitForVelocity	(	NBody	forNbody,
		NBody	aroundNBody,
		Vector3	velocity
	)

Computes the orbit parameters for a specified velocity with respect to a central body. This method assumes the orbit is not a Kepler-mode orbit ellipse. If it is (or not sure) then use SetOrbit() below.

Parameters

forNbody
aroundNBody
velocity

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

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