org.kynosarges.tektosyne.graph

Class NodeArc

java.lang.Object

org.kynosarges.tektosyne.graph.NodeArc

public final class NodeArc
extends java.lang.Object

Defines the visibility of a Graph node from a source node. Encapsulates data required by the Visibility line-of-sight algorithm. The Graph node that defines the NodeArc and the source node that defines the viewpoint are not stored in the NodeArc.

Field Summary

Fields

Modifier and Type	Field and Description
double	distance The positive distance from the source node to the NodeArc.

Method Summary

Modifier and Type	Method and Description
int	isObscured(NodeArc arc) Determines whether the current NodeArc completely obscures the specified instance, or vice versa.
double	start() Gets the starting angle of the NodeArc.
double	sweep() Gets the positive sweep angle of the NodeArc.
double	visibleFraction() Gets the visible fraction of the NodeArc.

Methods inherited from class java.lang.Object

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

Field Detail

distance

public final double distance

The positive distance from the source node to the NodeArc. Measured in world coordinates from the Graph.getWorldLocation(T) result for the source node to the nearest vertex of the Graph.getWorldRegion(T) result for the graph node that defines the tangential arc.

Method Detail

start

public double start()

Gets the starting angle of the NodeArc. Measured clockwise in radians from the x-axis, assuming y-coordinates increase upward.

Returns:

the starting angle of the NodeArc

sweep

public double sweep()

Gets the positive sweep angle of the NodeArc. Measured clockwise in radians, assuming y-coordinates increase upward. Never zero or negative in published NodeArc instances, but set to zero for some instances internally used by the Visibility algorithm.

Returns:

the positive sweep angle of the NodeArc

visibleFraction

public double visibleFraction()

Gets the visible fraction of the NodeArc. Defaults to one for a newly created NodeArc. May be inaccurate if it is smaller than the current Visibility.threshold(), as the Visibility algorithm stops updating a NodeArc as soon as it is considered obscured.

Returns:

the fraction of the sweep() angle that remains unobscured, from zero to one

isObscured

public int isObscured(NodeArc arc)

Determines whether the current NodeArc completely obscures the specified instance, or vice versa. Takes the distance of both instances into account to determine which instance obscures the other, if any.

Parameters:

arc - the other NodeArc to examine

Returns:

zero if neither NodeArc completely obscures the other; less than zero if arc completely obscures this instance; greater than zero if this instance completely obscures arc

Throws:

java.lang.NullPointerException - if arc is null