gov.nasa.worldwind.shape

Class Ellipse

java.lang.Object

gov.nasa.worldwind.render.AbstractRenderable

gov.nasa.worldwind.shape.AbstractShape

gov.nasa.worldwind.shape.Ellipse

All Implemented Interfaces:

Renderable, Attributable, Highlightable

public class Ellipse
extends AbstractShape

Ellipse shape defined by a geographic center position and radii for the semi-major and semi-minor axes.

Axes and Heading

Ellipse axes, by default, are oriented such that the semi-major axis points East and the semi-minor axis points North. Ellipse provides an optional heading, which when set to anything other than 0.0 rotates the semi-major and semi-minor axes about the center position, while retaining the axes relative relationship to one another. Heading is defined in degrees clockwise from North. Configuring ellipse with a heading of 45.0 results in the semi-major axis pointing Southeast and the semi-minor axis pointing Northeast.

Altitude Mode and Terrain Following

Ellipse geometry displays at a constant altitude determined by the geographic center position and altitude mode. For example, an ellipse with a center position altitude of 1km and altitude mode of ABSOLUTE displays at 1km above mean sea level. The same ellipse with an altitude mode of RELATIVE_TO_GROUND displays at 1km above ground level, relative to the ellipse's center location.

Surface ellipse geometry, where an ellipse appears draped across the terrain, may be achieved by enabling ellipse's terrain following state and setting its altitude mode to CLAMP_TO_GROUND. See setFollowTerrain(boolean) and AbstractShape.setAltitudeMode(int).

Display Granularity

Ellipse's appearance on screen is composed of discrete segments which approximate the ellipse's geometry. This approximation is chosen such that the display appears to be a continuous smooth ellipse. Applications can control the maximum number of angular intervals used in this representation with setMaximumIntervals(int).

Constructor Summary

Constructors

Constructor and Description
Ellipse() Constructs an ellipse with a null center position, and with major- and minor-radius both 0.0.
Ellipse(Position center, double majorRadius, double minorRadius) Constructs an ellipse with a specified center position and radii.
Ellipse(Position center, double majorRadius, double minorRadius, ShapeAttributes attributes) Constructs an ellipse with a specified center position, radii, and shape attributes.
Ellipse(ShapeAttributes attributes) Constructs an ellipse with a null center position, and with major- and minor-radius both 0.0.

Method Summary

Modifier and Type	Method and Description
Position	getCenter() Indicates the geographic position of this ellipse's center.
double	getHeading() Indicates this ellipse's heading.
double	getMajorRadius() Indicates the radius of this globe's semi-major axis.
int	getMaximumIntervals() Indicates the maximum number of angular intervals that may be used to approximate this ellipse's geometry on screen.
double	getMinorRadius() Indicates the radius of this globe's semi-minor axis.
boolean	isExtrude()
boolean	isFollowTerrain() Indicates whether this ellipse's geometry follows the terrain surface or is fixed at a constant altitude.
Ellipse	setCenter(Position position) Sets the geographic position of this ellipse's center.
Ellipse	setExtrude(boolean extrude)
Ellipse	setFollowTerrain(boolean followTerrain) Sets the terrain following state of this ellipse, which indicates whether this ellipse's geometry follows the terrain surface or is fixed at a constant altitude.
Ellipse	setHeading(double degrees) Sets this ellipse's heading in degrees clockwise from North.
Ellipse	setMajorRadius(double radius) Sets the radius of this globe's semi-major axis.
Ellipse	setMaximumIntervals(int numIntervals) Sets the maximum number of angular intervals that may be used to approximate this ellipse's on screen.
Ellipse	setMinorRadius(double radius) Sets the radius of this globe's semi-minor axis.

Methods inherited from class gov.nasa.worldwind.shape.AbstractShape

getAltitudeMode, getAttributes, getHighlightAttributes, getMaximumIntermediatePoints, getPathType, isHighlighted, setAltitudeMode, setAttributes, setHighlightAttributes, setHighlighted, setMaximumIntermediatePoints, setPathType

Methods inherited from class gov.nasa.worldwind.render.AbstractRenderable

getDisplayName, getPickDelegate, getUserProperty, hasUserProperty, isEnabled, putUserProperty, removeUserProperty, render, setDisplayName, setEnabled, setPickDelegate

Methods inherited from class java.lang.Object

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

Constructor Detail

Ellipse

public Ellipse()

Constructs an ellipse with a null center position, and with major- and minor-radius both 0.0. This ellipse does not display until the center position is defined and the radii are both greater than 0.0.

Ellipse

public Ellipse(ShapeAttributes attributes)

Constructs an ellipse with a null center position, and with major- and minor-radius both 0.0. This ellipse does not display until the center position is defined and the radii are both greater than 0.0.

Parameters:

attributes - the shape attributes applied to the ellipse

Ellipse

public Ellipse(Position center,
               double majorRadius,
               double minorRadius)

Constructs an ellipse with a specified center position and radii. The ellipse displays in the default shape attributes, which may be specified using AbstractShape.setAttributes(ShapeAttributes). The ellipse does not display if the center position is null, or both radii are 0.0.

Parameters:

center - geographic position at the ellipse's center. May be null.

majorRadius - radius of the semi-major axis, in meters.

minorRadius - radius of the semi-minor axis, in meters.

Throws:

java.lang.IllegalArgumentException - If either radius is negative

Ellipse

public Ellipse(Position center,
               double majorRadius,
               double minorRadius,
               ShapeAttributes attributes)

Constructs an ellipse with a specified center position, radii, and shape attributes. The ellipse displays in the specified shape attributes, which may be modifies using AbstractShape.setAttributes(ShapeAttributes). The ellipse does not display if the center position is null, or both radii are 0.0.

Parameters:

center - geographic position at the ellipse's center; may be null

majorRadius - radius of the semi-major axis, in meters.

minorRadius - radius of the semi-minor axis, in meters.

attributes - the shape attributes applied to the ellipse

Throws:

java.lang.IllegalArgumentException - If either radius is negative

Method Detail

getCenter

public Position getCenter()

Indicates the geographic position of this ellipse's center. The position may be null, in which case the ellipse does not display.

Returns:

this ellipse's geographic center; may be null

setCenter

public Ellipse setCenter(Position position)

Sets the geographic position of this ellipse's center. The position may be null, in which case the ellipse does not display.

Parameters:

position - the new center position; may be null

Returns:

this ellipse with its center position set to the specified position

getMajorRadius

public double getMajorRadius()

Indicates the radius of this globe's semi-major axis. When the ellipse's heading is 0.0, the semi-major axis points East.

Returns:

the radius, in meters

setMajorRadius

public Ellipse setMajorRadius(double radius)

Sets the radius of this globe's semi-major axis. When the ellipse's heading is 0.0, the semi-major axis points East.

Parameters:

radius - the new radius, in meters

Returns:

this ellipse with the radius of its semi-major axis set to the specified value

Throws:

java.lang.IllegalArgumentException - If the radius is negative

getMinorRadius

public double getMinorRadius()

Indicates the radius of this globe's semi-minor axis. When the ellipse's heading is 0.0, the semi-minor axis points North.

Returns:

the radius, in meters

setMinorRadius

public Ellipse setMinorRadius(double radius)

Sets the radius of this globe's semi-minor axis. When the ellipse's heading is 0.0, the semi-minor axis points North.

Parameters:

radius - the new radius, in meters

Returns:

this ellipse with the radius of its semi-minor axis set to the specified value

Throws:

java.lang.IllegalArgumentException - If the radius is negative

getHeading

public double getHeading()

Indicates this ellipse's heading. When ellipse's heading is 0.0, the semi-major axis points East and the semi-minor axis points North. Headings other than 0.0 rotate the axes about the ellipse's center position, while retaining the axes relative relationship to one another.

Returns:

this ellipse's heading, in degrees clockwise from North

setHeading

public Ellipse setHeading(double degrees)

Sets this ellipse's heading in degrees clockwise from North. When ellipse's heading is 0.0, the semi-major axis points East and the semi-minor axis points North. Headings other than 0.0 rotate the axes about the ellipse's center position, while retaining the axes relative relationship to one another.

Parameters:

degrees - the new heading, in degrees clockwise from North

Returns:

this ellipse, with its heading set to the specified value

isExtrude

public boolean isExtrude()

setExtrude

public Ellipse setExtrude(boolean extrude)

isFollowTerrain

public boolean isFollowTerrain()

Indicates whether this ellipse's geometry follows the terrain surface or is fixed at a constant altitude.

Returns:

true if ellipse geometry follows the terrain surface, and false otherwise

setFollowTerrain

public Ellipse setFollowTerrain(boolean followTerrain)

Sets the terrain following state of this ellipse, which indicates whether this ellipse's geometry follows the terrain surface or is fixed at a constant altitude. By default the terrain following state is false, and ellipse geometry follows the constant altitude of its center position.

Parameters:

followTerrain - true to follow the terrain surface, and false otherwise

Returns:

this ellipse, with its terrain following state set to the specified value

getMaximumIntervals

public int getMaximumIntervals()

Indicates the maximum number of angular intervals that may be used to approximate this ellipse's geometry on screen.

Returns:

the number of angular intervals

setMaximumIntervals

public Ellipse setMaximumIntervals(int numIntervals)

Sets the maximum number of angular intervals that may be used to approximate this ellipse's on screen.

Ellipse may use a minimum number of intervals to ensure that its appearance on screen at least roughly approximates the ellipse's shape. When the specified number of intervals is too small, it is clamped to an implementation-defined minimum number of intervals.

Ellipse may require that the number of intervals is an even multiple of some integer. When the specified number of intervals does not meet this criteria, the next smallest integer that meets ellipse's criteria is used instead.

Parameters:

numIntervals - the number of angular intervals

Returns:

this ellipse with its number of angular intervals set to the specified value

Throws:

java.lang.IllegalArgumentException - If the number of intervals is negative