com.threerings.media.util
Class LineSegmentPath

java.lang.Object
  com.threerings.media.util.LineSegmentPath

All Implemented Interfaces:

Path, DirectionCodes

Direct Known Subclasses:

TilePath

public class LineSegmentPath
extends Object
implements DirectionCodes, Path

The line segment path is used to cause a pathable to follow a path that is made up of a sequence of line segments. There must be at least two nodes in any worthwhile path. The direction of the first node in the path is meaningless since the pathable begins at that node and will therefore never be heading towards it.

Field Summary

protected PathNode	_dest When moving, the pathable's destination path node.
protected float	_fracx The distance to move on the straight path line per tick.
protected float	_fracy The distance to move on the straight path line per tick.
protected float	_incx When moving, the distance to move on each axis per tick.
protected float	_incy When moving, the distance to move on each axis per tick.
protected float	_movex When moving, the pathable position including fractional pixels.
protected float	_movey When moving, the pathable position including fractional pixels.
protected Iterator<PathNode>	_niter We use this when moving along this path.
protected ArrayList<PathNode>	_nodes The nodes that make up the path.
protected long	_nodestamp The time at which we started traversing the current node.
protected float	_seglength The length in pixels of the current path segment.
protected PathNode	_src When moving, the pathable's source path node.
protected float	_vel The path velocity in pixels per millisecond.
protected static float	DEFAULT_VELOCITY Default pathable velocity.

Fields inherited from interface com.threerings.util.DirectionCodes

CARDINAL_DIRECTIONS, CCW, CW, DIRECTION_COUNT, DOWN, EAST, EASTNORTHEAST, EASTSOUTHEAST, FINE_DIRECTION_COUNT, HORIZONTAL, LEFT, NONE, NORTH, NORTHEAST, NORTHNORTHEAST, NORTHNORTHWEST, NORTHWEST, RIGHT, SOUTH, SOUTHEAST, SOUTHSOUTHEAST, SOUTHSOUTHWEST, SOUTHWEST, UP, VERTICAL, WEST, WESTNORTHWEST, WESTSOUTHWEST

Constructor Summary

LineSegmentPath()
Constructs an empty line segment path.

LineSegmentPath(int x1, int y1, int x2, int y2)
Constructs a line segment path that consists of a single segment connecting the point (x1, y1) with (x2, y2).

LineSegmentPath(List<Point> points)
Constructs a line segment path with the specified list of points.

LineSegmentPath(Point p1, Point p2, int dir)
Construct a line segment path between the two nodes with the specified direction.

Method Summary

void	addNode(int x, int y, int dir) Add a node to the path with the specified destination point and facing direction.
protected void	createPath(List<Point> points) Populate the path with the path nodes that lead the pathable from its starting position to the given destination coordinates following the given list of screen coordinates.
void	fastForward(long timeDelta) This is called if the pathable is paused for some length of time and then unpaused.
int	getFinalOrientation() Returns the orientation the sprite will face at the end of the path.
protected PathNode	getNextNode() Gets the next node in the path.
PathNode	getNode(int idx) Return the requested node index in the path, or null if no such index exists.
protected boolean	headToNextNode(Pathable pable, long startstamp, long now) Place the pathable moving along the path at the end of the previous path node, face it appropriately for the next node, and start it on its way.
void	init(Pathable pable, long timestamp) Called once to let the path prepare itself for the process of animating the supplied pathable.
void	paint(Graphics2D gfx) Paint this path on the screen (used for debugging purposes only).
void	setDuration(long millis) Computes the velocity at which the pathable will need to travel along this path such that it will arrive at the destination in approximately the specified number of milliseconds.
void	setVelocity(float velocity) Sets the velocity of this pathable in pixels per millisecond.
int	size() Return the number of nodes in the path.
boolean	tick(Pathable pable, long timestamp) Called to request that this path update the position of the specified pathable based on the supplied timestamp information.
String	toString()
void	wasRemoved(Pathable pable) When a path is removed from a pathable, whether that is because the path was completed or because it was replaced by another path, this method will be called to let the path know that it is no longer associated with this pathable.

Methods inherited from class java.lang.Object

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

Field Detail

_nodes

protected ArrayList<PathNode> _nodes

The nodes that make up the path.

_niter

protected Iterator<PathNode> _niter

We use this when moving along this path.

_src

protected PathNode _src

When moving, the pathable's source path node.

_dest

protected PathNode _dest

When moving, the pathable's destination path node.

_nodestamp

protected long _nodestamp

The time at which we started traversing the current node.

_seglength

protected float _seglength

The length in pixels of the current path segment.

_vel

protected float _vel

The path velocity in pixels per millisecond.

_movex

protected float _movex

When moving, the pathable position including fractional pixels.

_movey

protected float _movey

When moving, the pathable position including fractional pixels.

_incx

protected float _incx

When moving, the distance to move on each axis per tick.

_incy

protected float _incy

When moving, the distance to move on each axis per tick.

_fracx

protected float _fracx

The distance to move on the straight path line per tick.

_fracy

protected float _fracy

The distance to move on the straight path line per tick.

DEFAULT_VELOCITY

protected static final float DEFAULT_VELOCITY

Default pathable velocity.

See Also:

Constant Field Values

Constructor Detail

LineSegmentPath

public LineSegmentPath()

Constructs an empty line segment path.

LineSegmentPath

public LineSegmentPath(int x1,
                       int y1,
                       int x2,
                       int y2)

Constructs a line segment path that consists of a single segment connecting the point (x1, y1) with (x2, y2). The orientation for the first node is set arbitrarily and the second node is oriented based on the vector between the two nodes (in top-down coordinates).

LineSegmentPath

public LineSegmentPath(Point p1,
                       Point p2,
                       int dir)

Construct a line segment path between the two nodes with the specified direction.

LineSegmentPath

public LineSegmentPath(List<Point> points)

Constructs a line segment path with the specified list of points. An arbitrary direction will be assigned to the starting node.

Method Detail

getFinalOrientation

public int getFinalOrientation()

Returns the orientation the sprite will face at the end of the path.

addNode

public void addNode(int x,
                    int y,
                    int dir)

Add a node to the path with the specified destination point and facing direction.

Parameters:

x - the x-position.

y - the y-position.

dir - the facing direction.

getNode

public PathNode getNode(int idx)

Return the requested node index in the path, or null if no such index exists.

Parameters:

idx - the node index.

Returns:

the path node.

size

public int size()

Return the number of nodes in the path.

setVelocity

public void setVelocity(float velocity)

Sets the velocity of this pathable in pixels per millisecond. The velocity is measured as pixels traversed along the path that the pathable is traveling rather than in the x or y directions individually. Note that the pathable velocity should not be changed while a path is being traversed; doing so may result in the pathable position changing unexpectedly.

Parameters:

velocity - the pathable velocity in pixels per millisecond.

setDuration

public void setDuration(long millis)

Computes the velocity at which the pathable will need to travel along this path such that it will arrive at the destination in approximately the specified number of milliseconds. Efforts are taken to get the pathable there as close to the desired time as possible, but framerate variation may prevent it from arriving exactly on time.

init

public void init(Pathable pable,
                 long timestamp)

Description copied from interface: Path

Called once to let the path prepare itself for the process of animating the supplied pathable. Path users should also call Path.tick(com.threerings.media.util.Pathable, long) after Path.init(com.threerings.media.util.Pathable, long) with the same initialization timestamp.

Specified by:

init in interface Path

tick

public boolean tick(Pathable pable,
                    long timestamp)

Description copied from interface: Path

Called to request that this path update the position of the specified pathable based on the supplied timestamp information. A path should record its initial timestamp and determine the progress of the pathable along the path based on the time elapsed since the pathable began down the path.

Specified by:

tick in interface Path

Parameters:

pable - the pathable whose position should be updated.

timestamp - the timestamp associated with this frame.

Returns:

true if the pathable's position was updated, false if the path determined that the pathable should not move at this time.

fastForward

public void fastForward(long timeDelta)

Description copied from interface: Path

This is called if the pathable is paused for some length of time and then unpaused. Paths should adjust any time stamps they are maintaining internally by the delta so that time maintains the illusion of flowing smoothly forward.

Specified by:

fastForward in interface Path

wasRemoved

public void wasRemoved(Pathable pable)

Description copied from interface: Path

When a path is removed from a pathable, whether that is because the path was completed or because it was replaced by another path, this method will be called to let the path know that it is no longer associated with this pathable.

Specified by:

wasRemoved in interface Path

headToNextNode

protected boolean headToNextNode(Pathable pable,
                                 long startstamp,
                                 long now)

Place the pathable moving along the path at the end of the previous path node, face it appropriately for the next node, and start it on its way. Returns whether the pathable position moved.

paint

public void paint(Graphics2D gfx)

Description copied from interface: Path

Paint this path on the screen (used for debugging purposes only).

Specified by:

paint in interface Path

toString

public String toString()

Overrides:

toString in class Object

createPath

protected void createPath(List<Point> points)

Populate the path with the path nodes that lead the pathable from its starting position to the given destination coordinates following the given list of screen coordinates.

getNextNode

protected PathNode getNextNode()

Gets the next node in the path.