org.lazywizard.lazylib.campaign.orbits

Class KeplerOrbit

Object

KeplerOrbit

All Implemented Interfaces:

OrbitAPI

public class KeplerOrbit
extends Object
implements OrbitAPI

Keplerian orbit simulation.

Since:

2.8

Author:

Liral

Field Summary

Fields

Modifier and Type	Field and Description
static float	MAXIMUM_AXIS
static float	MAXIMUM_ECCENTRICITY
static float	MAXIMUM_PERIOD
static float	MINIMUM_AXIS
static float	MINIMUM_ECCENTRICITY
static float	MINIMUM_PERIOD

Constructor Summary

Constructors

Constructor and Description
KeplerOrbit(SectorEntityToken focus, float semiMajorAxis, float semiMinorAxis, float angle, float period, boolean clockwise) Elliptical Kepler Orbit of one body around another.

Method Summary

Modifier and Type	Method and Description
void	advance(float amount) Called by Starsector itself - you can ignore this.
Vector2f	computeCurrentLocation()
SectorEntityToken	getFocus()
float	getOrbitalPeriod()
OrbitAPI	makeCopy()
void	setEntity(SectorEntityToken entity) Called by Starsector itself - you can ignore this.
void	updateLocation()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MINIMUM_ECCENTRICITY

public static final float MINIMUM_ECCENTRICITY

See Also:

Constant Field Values

MAXIMUM_ECCENTRICITY

public static final float MAXIMUM_ECCENTRICITY

See Also:

Constant Field Values

MINIMUM_AXIS

public static final float MINIMUM_AXIS

See Also:

Constant Field Values

MAXIMUM_AXIS

public static final float MAXIMUM_AXIS

See Also:

Constant Field Values

MINIMUM_PERIOD

public static final float MINIMUM_PERIOD

See Also:

Constant Field Values

MAXIMUM_PERIOD

public static final float MAXIMUM_PERIOD

See Also:

Constant Field Values

Constructor Detail

KeplerOrbit

public KeplerOrbit(SectorEntityToken focus,
                   float semiMajorAxis,
                   float semiMinorAxis,
                   float angle,
                   float period,
                   boolean clockwise)

Elliptical Kepler Orbit of one body around another.

Approximates the orbit of a body to a patched conic orbit of given orbital elements and thereafter advances the position of the body by calculating its eccentric anomaly on the patched conic orbit with an iterative Newton-Raphson solution to Kepler's Equation.

Sets the eccentric anomaly to the mean anomaly whenever the Newton-Raphson method yields no solution.

Prevents absurdity and ensures numerical stability by adjusting or clamping impossible or extreme orbital elements:

Sets each axis to its absolute value, clamped to [100.0f, 1000000.0f], and respectively sets the semi-minor and semi-major axis to the lesser and greater of the two resulting values. Slightly shifts the resulting semi-major axis should it entail an orbit of such orbital eccentricity (eccentricity = 1 - semiMinorAxis/semiMajorAxis < 0.9990000128746033f) or so nearly circular (eccentricity < 0.0010000000474974513f)) that the Newton-Raphson method would be numerically-unstable. Sets the angle to its absolute value. Sets the period to its absolute value, clamped to [10.0f, 1000000.0f].

Parameters:

focus - SectorEntityToken whereabout the body orbits

semiMajorAxis - float length of the semi-minor axis, which is the distance from the focus to the orbital point furthest from it

semiMinorAxis - float length of the semi-minor axis, which is the distance from the focus to either of the two points where a line perpendicular to the semiMajorAxis intersects the orbit

angle - float degrees counterclockwise from horizontally right to the 'first' semi-major axis

period - float duration of one orbit in days

clockwise - boolean whether the orbit is clockwise (true) or counterclockwise (false)

Method Detail

getFocus

public SectorEntityToken getFocus()

Specified by:

getFocus in interface OrbitAPI

Returns:

SectorEntityToken orbited

setEntity

public void setEntity(SectorEntityToken entity)

Called by Starsector itself - you can ignore this.

Specified by:

setEntity in interface OrbitAPI

Parameters:

entity - entity that's doing the orbiting.

advance

public void advance(float amount)

Called by Starsector itself - you can ignore this.

Specified by:

advance in interface OrbitAPI

makeCopy

public OrbitAPI makeCopy()

Specified by:

makeCopy in interface OrbitAPI

computeCurrentLocation

public Vector2f computeCurrentLocation()

Specified by:

computeCurrentLocation in interface OrbitAPI

getOrbitalPeriod

public float getOrbitalPeriod()

Specified by:

getOrbitalPeriod in interface OrbitAPI

updateLocation

public void updateLocation()

Specified by:

updateLocation in interface OrbitAPI