Package edu.cnu.mdi.mdi3D.item3D

Class Trajectory3D

java.lang.Object

edu.cnu.mdi.mdi3D.item3D.Item3D

edu.cnu.mdi.mdi3D.item3D.PolyLine3D

edu.cnu.mdi.mdi3D.item3D.Trajectory3D

public class Trajectory3D
extends PolyLine3D

A dynamic 3D trajectory item that grows by appending points over time.

This class extends PolyLine3D by adding simple trajectory semantics: points can be appended one at a time, the trajectory can be cleared, and an optional maximum point count can be enforced.

Internally, the trajectory is stored as a flat coordinate array in the form:

 [x1, y1, z1, x2, y2, z2, ..., xn, yn, zn]
 

Consecutive points are connected by straight line segments when drawn.

If a maximum point count is specified and the trajectory exceeds that limit, the oldest point is discarded so that the most recent points remain visible. This implementation uses a simple array shift when discarding old points. That keeps the code straightforward and is usually adequate for demo-scale trajectories.

Allocation strategy

A single backing buffer is owned by this class and never exposed to PolyLine3D's drawing path as a trimmed copy. Instead, PolyLine3D.setCoords(float[], int) is used so the draw loop reads only the live slice of the buffer, eliminating the per-append allocation that the naive Arrays.copyOf approach would incur.

Field Summary

Fields inherited from class edu.cnu.mdi.mdi3D.item3D.Item3D

_panel3D, FILLALPHA, FILLCOLOR, FONT, LINE_WIDTH, LINEALPHA, LINECOLOR, TEXT_COLOR

Constructor Summary

Constructors

Constructor	Description
Trajectory3D(Panel3D panel3D, Color color, float lineWidth)	Creates an unbounded trajectory with a default initial capacity.
Trajectory3D(Panel3D panel3D, Color color, float lineWidth, int maxPoints)	Creates a trajectory with an optional maximum number of points.
Trajectory3D(Panel3D panel3D, Color color, float lineWidth, int maxPoints, int initialCapacity)	Creates a trajectory with full control over maximum point count and initial storage capacity.

Method Summary

Modifier and Type	Method	Description
void	append(float[] xyz)	Appends a new point to the end of the trajectory.
void	append(float x, float y, float z)	Appends a new point to the end of the trajectory.
void	clear()	Removes all points from the trajectory.
int	getMaxPoints()	Gets the maximum allowed number of points.
int	getPointCount()	Gets the current number of points in the trajectory.
boolean	isEmpty()	Checks whether the trajectory is empty.

Methods inherited from class edu.cnu.mdi.mdi3D.item3D.PolyLine3D

draw, getCentroid, getCoords, getLivePoints, getSortPoint, setCoords, setCoords

Methods inherited from class edu.cnu.mdi.mdi3D.item3D.Item3D

addChild, defaultProperties, dispose, disposeItem, drawItem, get, getChildren, getColor, getFillAlpha, getFillColor, getFloat, getFont, getFont, getInt, getLineAlpha, getLineColor, getLineWidth, getPanel3D, getParent, getString, getTextColor, isVisible, put, removeChild, setAlphaOfColor, setFillAlpha, setFillColor, setFont, setLineAlpha, setLineColor, setLineWidth, setTextColor, setVisible

Methods inherited from class java.lang.Object

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

Constructor Details

Trajectory3D

public Trajectory3D(Panel3D panel3D,
 Color color,
 float lineWidth)

Creates an unbounded trajectory with a default initial capacity.

Parameters:

panel3D - the owning 3D panel

color - the trajectory color

lineWidth - the trajectory line width

Trajectory3D

public Trajectory3D(Panel3D panel3D,
 Color color,
 float lineWidth,
 int maxPoints)

Creates a trajectory with an optional maximum number of points.

Parameters:

panel3D - the owning 3D panel

color - the trajectory color

lineWidth - the trajectory line width

maxPoints - the maximum number of points to retain; values less than or equal to zero mean no explicit maximum

Trajectory3D

public Trajectory3D(Panel3D panel3D,
 Color color,
 float lineWidth,
 int maxPoints,
 int initialCapacity)

Creates a trajectory with full control over maximum point count and initial storage capacity.

Parameters:

panel3D - the owning 3D panel

color - the trajectory color

lineWidth - the trajectory line width

maxPoints - the maximum number of points to retain; values less than or equal to zero mean no explicit maximum

initialCapacity - the initial storage capacity in points; values less than 2 are promoted to 2

Method Details

append

public void append(float x,
 float y,
 float z)

Appends a new point to the end of the trajectory.

If the trajectory has a fixed maximum size and is already full, the oldest point is discarded before the new point is appended. No allocation occurs unless the backing buffer needs to grow.

Parameters:

x - the x coordinate of the new point

y - the y coordinate of the new point

z - the z coordinate of the new point

append

public void append(float[] xyz)

Appends a new point to the end of the trajectory.

Parameters:

xyz - the point coordinates as [x, y, z]

Throws:

IllegalArgumentException - if the array is null or has length less than 3

clear

public void clear()

Removes all points from the trajectory.

After calling this method, nothing will be drawn until at least two points have been appended. The backing buffer is retained so that a subsequent fill does not re-allocate.

getPointCount

public int getPointCount()

Gets the current number of points in the trajectory.

Returns:

the number of stored points

getMaxPoints

public int getMaxPoints()

Gets the maximum allowed number of points.

Returns:

the maximum number of points, or a value less than or equal to zero if the trajectory is unbounded

isEmpty

public boolean isEmpty()

Checks whether the trajectory is empty.

Returns:

true if no points are stored, false otherwise