Geometry Generation
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import javax.swing.*;
import no.geosoft.cc.geometry.Geometry;
import no.geosoft.cc.graphics.*;
/**
* G demo program. Demonstrates:
*
* <ul>
* <li> A math application
* <li> Polyline performance
* <li> Geometry generation
* </ul>
*
* @author <a href="mailto:jacob.dreyer@geosoft.no">Jacob Dreyer</a>
*/
public class Demo20 extends JFrame
implements ActionListener
{
private JButton addLevelButton_;
private JButton removeLevelButton_;
private JLabel nEdgesLabel_;
private JLabel lengthLabel_;
private JLabel areaLabel_;
private KochSnowflake kochSnowflake_;
public Demo20()
{
super ("G Graphics Library - Demo 20");
setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
JPanel controlPanel = new JPanel();
addLevelButton_ = new JButton("+");
addLevelButton_.addActionListener (this);
controlPanel.add (addLevelButton_);
removeLevelButton_ = new JButton("-");
removeLevelButton_.addActionListener (this);
controlPanel.add (removeLevelButton_);
nEdgesLabel_ = new JLabel();
controlPanel.add (nEdgesLabel_);
lengthLabel_ = new JLabel();
controlPanel.add (lengthLabel_);
areaLabel_ = new JLabel();
controlPanel.add (areaLabel_);
getContentPane().add (controlPanel, BorderLayout.NORTH);
// Create the graphic canvas
GWindow window = new GWindow (new Color (255, 255, 255));
getContentPane().add (window.getCanvas(), BorderLayout.CENTER);
// Create scene with default viewport and world extent settings
GScene scene = new GScene (window);
double w0[] = {0.0, 0.0, 0.0};
double w1[] = {1.0, 0.0, 0.0};
double w2[] = {0.0, 1.0, 0.0};
scene.setWorldExtent (w0, w1, w2);
// Create the graphics object and add to the scene
kochSnowflake_ = new KochSnowflake();
scene.add (kochSnowflake_);
pack();
setSize (new Dimension (500, 500));
setVisible (true);
window.startInteraction (new ZoomInteraction (scene));
refresh();
}
public void actionPerformed (ActionEvent event)
{
if (event.getSource() == addLevelButton_)
kochSnowflake_.addLevel();
else
kochSnowflake_.removeLevel();
refresh();
}
public void refresh()
{
nEdgesLabel_.setText ("#edges = " + kochSnowflake_.getNEdges());
DecimalFormat format = new DecimalFormat ("0.00000");
double length = kochSnowflake_.computeLength();
lengthLabel_.setText (" Length = " + format.format (length));
double area = kochSnowflake_.computeArea();
areaLabel_.setText (" Area = " + format.format (area));
kochSnowflake_.refresh();
}
/**
* Defines the geometry and presentation for the sample
* graphic object.
*/
private class KochSnowflake extends GObject
{
private GSegment curve_;
private double[] geometry_;
KochSnowflake()
{
GStyle style = new GStyle();
style.setForegroundColor (new Color (255, 0, 0));
style.setBackgroundColor (new Color (255, 255, 0));
setStyle (style);
curve_ = new GSegment();
geometry_ = new double[] {0.2, 0.2,
0.8, 0.2,
0.5, 0.2 + 0.6 * Math.sin (Math.PI / 3.0),
0.2, 0.2};
addSegment (curve_);
}
public int getNEdges()
{
return geometry_.length / 2 - 1;
}
public double computeLength()
{
double length = 0;
for (int i = 0; i < geometry_.length - 2; i += 2) {
length += Geometry.length (geometry_[i+0], geometry_[i+1],
geometry_[i+2], geometry_[i+3]);
}
return length;
}
public double computeArea()
{
return Geometry.computePolygonArea (geometry_);
}
public void addLevel()
{
int nLegs = geometry_.length / 2 - 1;
int nPoints = nLegs * 4 * 2 + 2;
double[] geometry = new double[nPoints];
int j = 0;
for (int i = 0; i < nLegs*2; i += 2) {
geometry[j+0] = geometry_[i+0];
geometry[j+1] = geometry_[i+1];
double[] v0 = Geometry.computePointOnLine (geometry_[i+0],
geometry_[i+1],
geometry_[i+2],
geometry_[i+3],
1.0 / 3.0);
geometry[j+2] = v0[0];
geometry[j+3] = v0[1];
double[] v1 = Geometry.computePointOnLine (geometry_[i+0],
geometry_[i+1],
geometry_[i+2],
geometry_[i+3],
2.0 / 3.0);
geometry[j+6] = v1[0];
geometry[j+7] = v1[1];
double length = Geometry.length (v0[0], v0[1], v1[0], v1[1]);
double dx = geometry_[i+2] - geometry_[i+0];
double dy = geometry_[i+3] - geometry_[i+1];
double l = Math.sqrt (dx * dx + dy * dy);
double angle = Math.acos (dx / l);
if (dy < 0) angle = 2.0 * Math.PI - angle;
angle -= Math.PI / 3.0;
geometry[j+4] = geometry[j+2] + length * Math.cos (angle);
geometry[j+5] = geometry[j+3] + length * Math.sin (angle);
j+= 8;
}
geometry[geometry.length-2] = geometry[0];
geometry[geometry.length-1] = geometry[1];
geometry_ = geometry;
redraw();
}
public void removeLevel()
{
int nLegs = geometry_.length / 2 - 1;
if (nLegs == 3) return;
int nPoints = nLegs / 4 * 2 + 2;
double[] geometry = new double[nPoints];
int j = 0;
for (int i = 0; i < geometry.length - 2; i += 2) {
geometry[i+0] = geometry_[j+0];
geometry[i+1] = geometry_[j+1];
j += 8;
}
geometry[geometry.length-2] = geometry[0];
geometry[geometry.length-1] = geometry[1];
geometry_ = geometry;
redraw();
}
public void draw()
{
curve_.setGeometryXy (geometry_);
}
}
public static void main (String[] args)
{
new Demo20();
}
}
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