Package edu.cnu.mdi.mdi3D.item3D

Class GlobeCountryLines3D

java.lang.Object

edu.cnu.mdi.mdi3D.item3D.Item3D

edu.cnu.mdi.mdi3D.item3D.GlobeCountryLines3D

public class GlobeCountryLines3D
extends Item3D

Draws country outlines on a sphere as 3D polyline strips.

Input polygons are provided as rings of Point2D.Double values where:

• x is longitude in radians (typically wrapped to [-pi, pi))
• y is latitude in radians ([-pi/2, pi/2])

This is the format produced by edu.cnu.mdi.mapping.GeoJsonCountryLoader.

Dateline seam handling

GeoJSON rings that cross the dateline can contain adjacent points whose longitudes differ by nearly 2*pi. If rendered as a continuous strip on the sphere, those segments would "cut across" the globe.

For demo purposes, this item takes a simple, robust approach: it splits the polyline whenever a segment exhibits |dLon| > pi. This avoids globe-spanning chords at the cost of a small seam gap at the dateline.

Rendering details

By default, vertices are placed slightly above the sphere surface (getRadialLift()) to reduce z-fighting with the sphere mesh.

Field Summary

Fields

Modifier and Type	Field	Description
static final double	DEFAULT_DATELINE_SPLIT_THRESHOLD	Threshold for splitting segments across the dateline seam.

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
GlobeCountryLines3D(Panel3D panel3D, List<edu.cnu.mdi.mapping.loader.GeoJsonCountryLoader.CountryFeature> features, float radius)	Construct a country outline renderer.

Method Summary

Modifier and Type	Method	Description
void	draw(com.jogamp.opengl.GLAutoDrawable drawable)	The custom drawing method
double	getDatelineSplitThreshold()	Get the current dateline split threshold.
Color	getLineColor()	Get the current outline color.
float	getLineWidth()	Get the current line width.
float	getRadialLift()	Get the radial lift.
final void	rebuild(List<edu.cnu.mdi.mapping.loader.GeoJsonCountryLoader.CountryFeature> features)	Rebuild the internal polyline strips from the provided features.
void	setDatelineSplitThreshold(double threshold)	Set the longitude discontinuity threshold (radians) used to split rings at the dateline.
void	setLineColor(Color c)	Set the outline color.
void	setLineWidth(float w)	Set the polyline width (OpenGL line width).
void	setRadialLift(float lift)	Set a small radial lift applied to all vertices to reduce z-fighting with the sphere.

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, getPanel3D, getParent, getSortPoint, getString, getTextColor, isVisible, put, removeChild, setAlphaOfColor, setFillAlpha, setFillColor, setFont, setLineAlpha, setTextColor, setVisible

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_DATELINE_SPLIT_THRESHOLD

public static final double DEFAULT_DATELINE_SPLIT_THRESHOLD

Threshold for splitting segments across the dateline seam.

See Also:

• Constant Field Values

Constructor Details

GlobeCountryLines3D

public GlobeCountryLines3D(Panel3D panel3D,
 List<edu.cnu.mdi.mapping.loader.GeoJsonCountryLoader.CountryFeature> features,
 float radius)

Construct a country outline renderer.

Parameters:

panel3D - the owning 3D panel

features - country features loaded from GeoJSON

radius - sphere radius in scene units

Method Details

rebuild

public final void rebuild(List<edu.cnu.mdi.mapping.loader.GeoJsonCountryLoader.CountryFeature> features)

Rebuild the internal polyline strips from the provided features.

Parameters:

features - country features

setLineColor

public void setLineColor(Color c)

Set the outline color.

Overrides:

setLineColor in class Item3D

Parameters:

c - the new color (non-null)

getLineColor

public Color getLineColor()

Get the current outline color.

Overrides:

getLineColor in class Item3D

Returns:

line color

setLineWidth

public void setLineWidth(float w)

Set the polyline width (OpenGL line width).

Overrides:

setLineWidth in class Item3D

Parameters:

w - width in pixels (values <= 0 are clamped to 1)

getLineWidth

public float getLineWidth()

Get the current line width.

Overrides:

getLineWidth in class Item3D

Returns:

line width in pixels

setRadialLift

public void setRadialLift(float lift)

Set a small radial lift applied to all vertices to reduce z-fighting with the sphere.

Parameters:

lift - radial lift in scene units (negative values treated as 0)

getRadialLift

public float getRadialLift()

Get the radial lift.

Returns:

radial lift in scene units

setDatelineSplitThreshold

public void setDatelineSplitThreshold(double threshold)

Set the longitude discontinuity threshold (radians) used to split rings at the dateline.

Parameters:

threshold - radians; values <= 0 revert to DEFAULT_DATELINE_SPLIT_THRESHOLD

getDatelineSplitThreshold

public double getDatelineSplitThreshold()

Get the current dateline split threshold.

Returns:

threshold in radians

draw

public void draw(com.jogamp.opengl.GLAutoDrawable drawable)

Description copied from class: Item3D

The custom drawing method

Specified by:

draw in class Item3D

Parameters:

drawable - the OpenGL drawable