Develop Reference

Worldwind PointPlacemark Pitch

I'm trying to figure out why the setPitch in the PointPlacemarkAttributes does not seem to work correctly.
I believe this JOGL code in PointPlacemark.java is where things are going wrong:
Double heading = getActiveAttributes().getHeading();
Double pitch = getActiveAttributes().getPitch();
// Adjust heading to be relative to globe or screen
if (heading != null)
{
if (AVKey.RELATIVE_TO_GLOBE.equals(this.getActiveAttributes().getHeadingReference()))
heading = dc.getView().getHeading().degrees - heading;
else
heading = -heading;
}
// Apply the heading and pitch if specified.
if (heading != null || pitch != null)
{
gl.glTranslated(xscale / 2, yscale / 2, 0);
if (pitch != null)
gl.glRotated(pitch, 1, 0, 0);
if (heading != null)
gl.glRotated(heading, 0, 0, 1);
gl.glTranslated(-xscale / 2, -yscale / 2, 0);
}
// Scale the unit quad
gl.glScaled(xscale, yscale, 1);
Here is a simple driver I've been using to play with it:
public class Placemarks extends ApplicationTemplate {
public static class AppFrame extends ApplicationTemplate.AppFrame {
public AppFrame() {
super(true, true, false);
final RenderableLayer layer = new RenderableLayer();
PointPlacemark pp = new PointPlacemark(Position.fromDegrees(28, -102, 30000));
pp.setLabelText("PointPlacemark");
pp.setLineEnabled(false);
pp.setAltitudeMode(WorldWind.ABSOLUTE);
PointPlacemarkAttributes attrs = new PointPlacemarkAttributes();
attrs.setImageAddress("gov/nasa/worldwindx/examples/images/georss.png");
attrs.setScale(1.0);
attrs.setImageOffset(Offset.CENTER);
attrs.setPitch(45.0);
pp.setAttributes(attrs);
layer.addRenderable(pp);
// Add the layer to the model.
insertBeforeCompass(getWwd(), layer);
}
}
public static void main(String[] args) {
ApplicationTemplate.start("WorldWind Placemarks", AppFrame.class);
}
}
If I set no pitch, it looks fine:
But when I set a pitch of 45 degrees it looks like this:
Which I'm not understanding how it correlates to the value I set. I'd expect it to work like the Compass does in the CompassLayer:
Update
Comment suggested to iterate through pitch values to see how it works. I did that and I'm still not seeing how it is supposed to work. It looks like it is just "cropping" the image horizontally, and not doing anything else. Here is some code:
public class Placemarks extends ApplicationTemplate {
public static class AppFrame extends ApplicationTemplate.AppFrame {
public AppFrame() {
super(true, true, false);
final RenderableLayer layer = new RenderableLayer();
PointPlacemark pp = new PointPlacemark(Position.fromDegrees(28, -102, 30000));
pp.setLabelText("PointPlacemark");
pp.setLineEnabled(false);
pp.setAltitudeMode(WorldWind.ABSOLUTE);
PointPlacemarkAttributes attrs = new PointPlacemarkAttributes();
attrs.setImageAddress("gov/nasa/worldwindx/examples/images/georss.png");
attrs.setScale(1.0);
attrs.setImageOffset(Offset.CENTER);
pp.setAttributes(attrs);
layer.addRenderable(pp);
// Add the layer to the model.
insertBeforeCompass(getWwd(), layer);
Thread t = new Thread(new Runnable() {
#Override
public void run() {
for(double i = 0.0; i<360; i+=.1) {
attrs.setPitch(i);
System.out.println("Pitch is now "+i);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
AppFrame.this.getWwd().redrawNow();
}
}
});
t.start();
}
}
public static void main(String[] args) {
ApplicationTemplate.start("WorldWind Placemarks", AppFrame.class);
}
}
And a screen recorded GIF:

The problem is that in PointPlacemark.doDrawOrderedRenderable(), the orthographic projection matrix used uses a range of depth values from -1 to 1.
When the pitch remains at 0, the z coordinates also remain at 0, safely in the middle of this range (actually, there is some slight fudging of this coordinate in WorldWind, but never mind that). As it pitches, of course the z coordinates change, until at 90° all of the y coordinates are 0 while z will go to half of the height of the image. This is why only a slice of the image that falls within the range -1,1 is visible while the rest is clipped.
That z range is defined by the following code:
// The image is drawn using a parallel projection.
osh.pushProjectionIdentity(gl);
gl.glOrtho(0d, dc.getView().getViewport().width, 0d, dc.getView().getViewport().height, -1d, 1d);
If we examine the equivalent code in CompassLayer, we can see that here they do factor in the scaled icon size (although the comment suggests that perhaps at some earlier iteration, less care had been taken over the z dimension):
double width = this.getScaledIconWidth();
double height = this.getScaledIconHeight();
// Load a parallel projection with xy dimensions (viewportWidth, viewportHeight)
// into the GL projection matrix.
java.awt.Rectangle viewport = dc.getView().getViewport();
ogsh.pushProjectionIdentity(gl);
double maxwh = width > height ? width : height;
if (maxwh == 0)
maxwh = 1;
gl.glOrtho(0d, viewport.width, 0d, viewport.height, -0.6 * maxwh, 0.6 * maxwh);
In this case, the arguments for z (±0.6 * maxwh) use 0.6 presumably as 0.5 plus some margin. The actual geometry is a unit quad, which is translated by half width/height in x/y, scaled and rotated accordingly.
For PointPlacemark, we can account for the size of the renderable in a similar way. Rearranging the code slightly so that scale computation happens before setting the projection, and adding a maxwh value:
// Compute the scale
double xscale;
Double scale = this.getActiveAttributes().getScale();
if (scale != null)
xscale = scale * this.activeTexture.getWidth(dc);
else
xscale = this.activeTexture.getWidth(dc);
double yscale;
if (scale != null)
yscale = scale * this.activeTexture.getHeight(dc);
else
yscale = this.activeTexture.getHeight(dc);
double maxwh = Math.max(xscale, yscale);
// The image is drawn using a parallel projection.
osh.pushProjectionIdentity(gl);
gl.glOrtho(0d, dc.getView().getViewport().width, 0d, dc.getView().getViewport().height, -0.6 * maxwh, 0.6 * maxwh);
Again, 0.6 allows some margin.
It would probably be perfectly fine to have hardcoded values for the z range, as long as they were large enough for any image we might want to draw but not so large that numerical precision became an issue. Conversely, one could go even further and factor in trig to work out the actual depth needed for a given rotation and image size, but there would not be much to gain by doing so.
This was indeed a bug with WorldWindJava that has been reported, along with a link here for the fix.

How to use AffineTransform with very little coordinates?

I have a set of two dimensions points. Their X and Y are greater than -2 and lesser than 2. Such point could be : (-0.00012 ; 1.2334 ).
I would want to display these points on a graph, using rectangles (a rectangle illustrates a point, and has its coordinates set to its point's ones - moreover, it has a size of 10*10).
Rectangles like (... ; Y) should be displayed above any rectangles like (... ; Y-1) (positive Y direction is up). Thus, I must set the graph's origin not at the top-left hand-corner, but somewhere else.
I'm trying to use Graphics2D's AffineTransform to do that.
I get the minimal value for all the X coordinates
I get the minimal value for all the Y coordinates
I get the maximal value for all the X coordinates
I get the maximal value for all the Y coordinates
I get the distance xmax-xmin and ymax-ymin
Then, I wrote the code I give you below.
Screenshots
Some days ago, using my own method to scale, I had this graph:
(so as I explained, Y are inverted and that's not a good thing)
For the moment, i.e., with the code I give you below, I have only one point that takes all the graph's place! Not good at all.
I would want to have:
(without lines, and without graph's axis. The important here is that points are correctly displayed, according to their coordinates).
Code
To get min and max coordinates value:
x_min = Double.parseDouble((String) list_all_points.get(0).get(0));
x_max = Double.parseDouble((String) list_all_points.get(0).get(0));
y_min = Double.parseDouble((String) list_all_points.get(0).get(1));
y_max = Double.parseDouble((String) list_all_points.get(0).get(1));
for(StorableData s : list_all_points) {
if(Double.parseDouble((String) s.get(0)) < x_min) {
x_min = Double.parseDouble((String) s.get(0));
}
if(Double.parseDouble((String) s.get(0)) > x_max) {
x_max = Double.parseDouble((String) s.get(0));
}
if(Double.parseDouble((String) s.get(1)) < y_min) {
y_min = Double.parseDouble((String) s.get(1));
}
if(Double.parseDouble((String) s.get(1)) > y_max) {
y_max = Double.parseDouble((String) s.get(1));
}
}
To draw a point:
int x, y;
private void drawPoint(Cupple storable_data) {
//x = (int) (storable_data.getNumber(0) * scaling_coef + move_x);
//y = (int) (storable_data.getNumber(1) * scaling_coef + move_y);
x = storable_data.getNumber(0).intValue();
y = storable_data.getNumber(1).intValue();
graphics.fillRect(x, y, 10, 10);
graphics.drawString(storable_data.toString(), x - 5, y - 5);
}
To paint the graph:
#Override
public void paint(Graphics graphics) {
this.graphics = graphics;
Graphics2D graphics_2d = ((Graphics2D) this.graphics);
AffineTransform affine_transform = graphics_2d.getTransform();
affine_transform.scale(getWidth()/(x_max - x_min), getHeight()/(y_max - y_min));
affine_transform.translate(x_min, y_min);
graphics_2d.transform(affine_transform);
for(StorableData storable_data : list_all_points) {
graphics_2d.setColor(Color.WHITE);
this.drawPoint((Cupple) storable_data);
}

I suggest you map each data point to a point on the screen, thus avoiding the following coordinate system pitfalls. Take your list of points and create from them a list of points to draw. Take into account that:
The drawing is pixel-based, so you will want to scale your points (or you would have rectangles 1 to 4 pixels wide...).
You will need to translate all your points because negative values will be outside the boundaries of the component on which you draw.
The direction of the y axis is reversed in the drawing coordinates.
Once that is done, use the new list of points for the drawing and the initial one for calculations. Here is an example:
public class Graph extends JPanel {
private static int gridSize = 6;
private static int scale = 100;
private static int size = gridSize * scale;
private static int translate = size / 2;
private static int pointSize = 10;
List<Point> dataPoints, scaledPoints;
Graph() {
setBackground(Color.WHITE);
// points taken from your example
Point p1 = new Point(-1, -2);
Point p2 = new Point(-1, 0);
Point p3 = new Point(1, 0);
Point p4 = new Point(1, -2);
dataPoints = Arrays.asList(p1, p2, p3, p4);
scaledPoints = dataPoints.stream()
.map(p -> new Point(p.x * scale + translate, -p.y * scale + translate))
.collect(Collectors.toList());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(size, size);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
// draw a grid
for (int i = 0; i < gridSize; i++) {
g2d.drawLine(i * scale, 0, i * scale, size);
g2d.drawLine(0, i * scale, size, i * scale);
}
// draw the rectangle
g2d.setPaint(Color.RED);
g2d.drawPolygon(scaledPoints.stream().mapToInt(p -> p.x).toArray(),
scaledPoints.stream().mapToInt(p -> p.y).toArray(),
scaledPoints.size());
// draw the points
g2d.setPaint(Color.BLUE);
// origin
g2d.fillRect(translate, translate, pointSize, pointSize);
g2d.drawString("(0, 0)", translate, translate);
// data
for (int i = 0; i < dataPoints.size(); i++) {
Point sp = scaledPoints.get(i);
Point dp = dataPoints.get(i);
g2d.fillRect(sp.x, sp.y, pointSize, pointSize);
g2d.drawString("(" + dp.x + ", " + dp.y + ")", sp.x, sp.y);
}
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setContentPane(new Graph());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
And another:
You might want to have the points aligned on the grid intersections and not below and to the right of them. I trust you will figure this one out.
Also, I ordered the points so that drawPolygon will paint the lines in the correct order. If your points are arbitrarily arranged, look for ways to find the outline. If you want lines between all points like in your example, iterate over all combinations of them with drawLine.

WorldWind line of sight

I've found this example of how to render line of sight in WorldWind: http://patmurris.blogspot.com/2008/04/ray-casting-and-line-of-sight-for-wwj.html (its a bit old, but it still seems to work). This is the class used in the example (slightly modified code below to work with WorldWind 2.0). It looks like the code also uses RayCastingSupport (Javadoc and Code) to do its magic.
What I'm trying to figure out is if this code/example is using the curvature of the earth/and or the distance to the horizon as part of its logic. Just looking at the code, I'm not sure I understand completely what it is doing.
For instance, if I was trying to figure out what terrain a person 200 meters above the earth could "see", would it take the distance to the horizon into account?
What would it take to modify the code to account for distance to the horizon/curvature of the earth (if its not already)?
package gov.nasa.worldwindx.examples;
import gov.nasa.worldwind.util.RayCastingSupport;
import gov.nasa.worldwind.view.orbit.OrbitView;
import gov.nasa.worldwind.geom.Angle;
import gov.nasa.worldwind.geom.Position;
import gov.nasa.worldwind.geom.Sector;
import gov.nasa.worldwind.geom.Vec4;
import gov.nasa.worldwind.globes.Globe;
import gov.nasa.worldwind.layers.CrosshairLayer;
import gov.nasa.worldwind.layers.RenderableLayer;
import gov.nasa.worldwind.render.*;
import javax.swing.*;
import javax.swing.border.CompoundBorder;
import javax.swing.border.TitledBorder;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
public class LineOfSight extends ApplicationTemplate
{
public static class AppFrame extends ApplicationTemplate.AppFrame
{
private double samplingLength = 30; // Ray casting sample length
private int centerOffset = 100; // meters above ground for center
private int pointOffset = 10; // meters above ground for sampled points
private Vec4 light = new Vec4(1, 1, -1).normalize3(); // Light direction (from South-East)
private double ambiant = .4; // Minimum lighting (0 - 1)
private RenderableLayer renderableLayer;
private SurfaceImage surfaceImage;
private ScreenAnnotation screenAnnotation;
private JComboBox radiusCombo;
private JComboBox samplesCombo;
private JCheckBox shadingCheck;
private JButton computeButton;
public AppFrame()
{
super(true, true, false);
// Add USGS Topo Maps
// insertBeforePlacenames(getWwd(), new USGSTopographicMaps());
// Add our renderable layer for result display
this.renderableLayer = new RenderableLayer();
this.renderableLayer.setName("Line of sight");
this.renderableLayer.setPickEnabled(false);
insertBeforePlacenames(getWwd(), this.renderableLayer);
// Add crosshair layer
insertBeforePlacenames(getWwd(), new CrosshairLayer());
// Update layer panel
this.getLayerPanel().update(getWwd());
// Add control panel
this.getLayerPanel().add(makeControlPanel(), BorderLayout.SOUTH);
}
private JPanel makeControlPanel()
{
JPanel controlPanel = new JPanel(new GridLayout(0, 1, 0, 0));
controlPanel.setBorder(
new CompoundBorder(BorderFactory.createEmptyBorder(9, 9, 9, 9),
new TitledBorder("Line Of Sight")));
// Radius combo
JPanel radiusPanel = new JPanel(new GridLayout(0, 2, 0, 0));
radiusPanel.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
radiusPanel.add(new JLabel("Max radius:"));
radiusCombo = new JComboBox(new String[] {"5km", "10km",
"20km", "30km", "50km", "100km", "200km"});
radiusCombo.setSelectedItem("10km");
radiusPanel.add(radiusCombo);
// Samples combo
JPanel samplesPanel = new JPanel(new GridLayout(0, 2, 0, 0));
samplesPanel.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
samplesPanel.add(new JLabel("Samples:"));
samplesCombo = new JComboBox(new String[] {"128", "256", "512"});
samplesCombo.setSelectedItem("128");
samplesPanel.add(samplesCombo);
// Shading checkbox
JPanel shadingPanel = new JPanel(new GridLayout(0, 2, 0, 0));
shadingPanel.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
shadingPanel.add(new JLabel("Light:"));
shadingCheck = new JCheckBox("Add shading");
shadingCheck.setSelected(false);
shadingPanel.add(shadingCheck);
// Compute button
JPanel buttonPanel = new JPanel(new GridLayout(0, 1, 0, 0));
buttonPanel.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
computeButton = new JButton("Compute");
computeButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent actionEvent)
{
update();
}
});
buttonPanel.add(computeButton);
// Help text
JPanel helpPanel = new JPanel(new GridLayout(0, 1, 0, 0));
buttonPanel.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
helpPanel.add(new JLabel("Place view center on an elevated"));
helpPanel.add(new JLabel("location and click \"Compute\""));
// Panel assembly
controlPanel.add(radiusPanel);
controlPanel.add(samplesPanel);
controlPanel.add(shadingPanel);
controlPanel.add(buttonPanel);
controlPanel.add(helpPanel);
return controlPanel;
}
// Update line of sight computation
private void update()
{
new Thread(new Runnable() {
public void run()
{
computeLineOfSight();
}
}, "LOS thread").start();
}
private void computeLineOfSight()
{
computeButton.setEnabled(false);
computeButton.setText("Computing...");
try
{
Globe globe = getWwd().getModel().getGlobe();
OrbitView view = (OrbitView)getWwd().getView();
Position centerPosition = view.getCenterPosition();
// Compute sector
String radiusString = ((String)radiusCombo.getSelectedItem());
double radius = 1000 * Double.parseDouble(radiusString.substring(0, radiusString.length() - 2));
double deltaLatRadians = radius / globe.getEquatorialRadius();
double deltaLonRadians = deltaLatRadians / Math.cos(centerPosition.getLatitude().radians);
Sector sector = new Sector(centerPosition.getLatitude().subtractRadians(deltaLatRadians),
centerPosition.getLatitude().addRadians(deltaLatRadians),
centerPosition.getLongitude().subtractRadians(deltaLonRadians),
centerPosition.getLongitude().addRadians(deltaLonRadians));
// Compute center point
double centerElevation = globe.getElevation(centerPosition.getLatitude(),
centerPosition.getLongitude());
Vec4 center = globe.computePointFromPosition(
new Position(centerPosition, centerElevation + centerOffset));
// Compute image
float hueScaleFactor = .7f;
int samples = Integer.parseInt((String)samplesCombo.getSelectedItem());
BufferedImage image = new BufferedImage(samples, samples, BufferedImage.TYPE_4BYTE_ABGR);
double latStepRadians = sector.getDeltaLatRadians() / image.getHeight();
double lonStepRadians = sector.getDeltaLonRadians() / image.getWidth();
for (int x = 0; x < image.getWidth(); x++)
{
Angle lon = sector.getMinLongitude().addRadians(lonStepRadians * x + lonStepRadians / 2);
for (int y = 0; y < image.getHeight(); y++)
{
Angle lat = sector.getMaxLatitude().subtractRadians(latStepRadians * y + latStepRadians / 2);
double el = globe.getElevation(lat, lon);
// Test line of sight from point to center
Vec4 point = globe.computePointFromPosition(lat, lon, el + pointOffset);
double distance = point.distanceTo3(center);
if (distance <= radius)
{
if (RayCastingSupport.intersectSegmentWithTerrain(
globe, point, center, samplingLength, samplingLength) == null)
{
// Center visible from point: set pixel color and shade
float hue = (float)Math.min(distance / radius, 1) * hueScaleFactor;
float shade = shadingCheck.isSelected() ?
(float)computeShading(globe, lat, lon, light, ambiant) : 0f;
image.setRGB(x, y, Color.HSBtoRGB(hue, 1f, 1f - shade));
}
else if (shadingCheck.isSelected())
{
// Center not visible: apply shading nonetheless if selected
float shade = (float)computeShading(globe, lat, lon, light, ambiant);
image.setRGB(x, y, new Color(0f, 0f, 0f, shade).getRGB());
}
}
}
}
// Blur image
PatternFactory.blur(PatternFactory.blur(PatternFactory.blur(PatternFactory.blur(image))));
// Update surface image
if (this.surfaceImage != null)
this.renderableLayer.removeRenderable(this.surfaceImage);
this.surfaceImage = new SurfaceImage(image, sector);
this.surfaceImage.setOpacity(.5);
this.renderableLayer.addRenderable(this.surfaceImage);
// Compute distance scale image
BufferedImage scaleImage = new BufferedImage(64, 256, BufferedImage.TYPE_4BYTE_ABGR);
Graphics g2 = scaleImage.getGraphics();
int divisions = 10;
int labelStep = scaleImage.getHeight() / divisions;
for (int y = 0; y < scaleImage.getHeight(); y++)
{
int x1 = scaleImage.getWidth() / 5;
if (y % labelStep == 0 && y != 0)
{
double d = radius / divisions * y / labelStep / 1000;
String label = Double.toString(d) + "km";
g2.setColor(Color.BLACK);
g2.drawString(label, x1 + 6, y + 6);
g2.setColor(Color.WHITE);
g2.drawLine(x1, y, x1 + 4 , y);
g2.drawString(label, x1 + 5, y + 5);
}
float hue = (float)y / (scaleImage.getHeight() - 1) * hueScaleFactor;
g2.setColor(Color.getHSBColor(hue, 1f, 1f));
g2.drawLine(0, y, x1, y);
}
// Update distance scale screen annotation
if (this.screenAnnotation != null)
this.renderableLayer.removeRenderable(this.screenAnnotation);
this.screenAnnotation = new ScreenAnnotation("", new Point(20, 20));
this.screenAnnotation.getAttributes().setImageSource(scaleImage);
this.screenAnnotation.getAttributes().setSize(
new Dimension(scaleImage.getWidth(), scaleImage.getHeight()));
this.screenAnnotation.getAttributes().setAdjustWidthToText(Annotation.SIZE_FIXED);
this.screenAnnotation.getAttributes().setDrawOffset(new Point(scaleImage.getWidth() / 2, 0));
this.screenAnnotation.getAttributes().setBorderWidth(0);
this.screenAnnotation.getAttributes().setCornerRadius(0);
this.screenAnnotation.getAttributes().setBackgroundColor(new Color(0f, 0f, 0f, 0f));
this.renderableLayer.addRenderable(this.screenAnnotation);
// Redraw
this.getWwd().redraw();
}
finally
{
computeButton.setEnabled(true);
computeButton.setText("Compute");
}
}
/**
* Compute shadow intensity at a globe position.
* #param globe the <code>Globe</code>.
* #param lat the location latitude.
* #param lon the location longitude.
* #param light the light direction vector. Expected to be normalized.
* #param ambiant the minimum ambiant light level (0..1).
* #return the shadow intensity for the location. No shadow = 0, totaly obscured = 1.
*/
private static double computeShading(Globe globe, Angle lat, Angle lon, Vec4 light, double ambiant)
{
double thirtyMetersRadians = 30 / globe.getEquatorialRadius();
Vec4 p0 = globe.computePointFromPosition(lat, lon, 0);
Vec4 px = globe.computePointFromPosition(lat, Angle.fromRadians(lon.radians - thirtyMetersRadians), 0);
Vec4 py = globe.computePointFromPosition(Angle.fromRadians(lat.radians + thirtyMetersRadians), lon, 0);
double el0 = globe.getElevation(lat, lon);
double elx = globe.getElevation(lat, Angle.fromRadians(lon.radians - thirtyMetersRadians));
double ely = globe.getElevation(Angle.fromRadians(lat.radians + thirtyMetersRadians), lon);
Vec4 vx = new Vec4(p0.distanceTo3(px), 0, elx - el0).normalize3();
Vec4 vy = new Vec4(0, p0.distanceTo3(py), ely - el0).normalize3();
Vec4 normal = vx.cross3(vy).normalize3();
return 1d - Math.max(-light.dot3(normal), ambiant);
}
}
public static void main(String[] args)
{
ApplicationTemplate.start("World Wind Line Of Sight Calculation", AppFrame.class);
}
}

You are correct. This code does not take into account the earth curve.
From what I could see, a ray trace is done for the center of the light but the cone of the light was drawn on an image (I am not sure about that, but it looks as if this example draws on an image of gray scale).
Any way this demo is about detecting hitting the ground to stop the ray trace.
From what I understand, the algorithm stops after a distance set in the form (5km,10km ... 200km etc.)
I don't understand the direction of the ray. It makes sense to check for 200km radius only if you check light from out of space....
If you want to take the horizon into account you should check the pitch of the light source first. Its relevant for positive pitch values (above the horizon).
In that case you should decide when to stop once the center of the light gets very high above ground. How high depends on whether you point your light towards a mountain slope of you terrain is relatively flat, or if the source of light is narrow beam or wide.

JFreeChart: how to set gradient paint for series in spider chart

I have a chart with this presentation:
But I require to do this:
How do I set correctly the gradient paint for series?. Here is what I have:
public class SpiderWebChartDemo1 extends ApplicationFrame {
public SpiderWebChartDemo1(String s) {
super(s);
JPanel jpanel = createDemoPanel();
jpanel.setPreferredSize(new Dimension(500, 270));
setContentPane(jpanel);
}
private static CategoryDataset createDataset() {
String s = "First";
String s3 = "Self leadership";
String s4 = "Organization leadership";
String s5 = "Team leadership";
DefaultCategoryDataset defaultcategorydataset = new DefaultCategoryDataset();
defaultcategorydataset.addValue(1.0D, s, s3);
defaultcategorydataset.addValue(4D, s, s4);
defaultcategorydataset.addValue(3D, s, s5);
return defaultcategorydataset;
}
private static JFreeChart createChart(CategoryDataset categorydataset) {
Color bckColor1 = Color.decode("#4282CE"); //Light blue
Color bckColor2 = Color.decode("#9BC1FF"); //Dark blue
Color axisColor = Color.decode("#DD0010"); //Red
SpiderWebPlot plot = new SpiderWebPlot(categorydataset);
Paint p = new GradientPaint(0,0,bckColor1,0,0,bckColor2);
plot.setSeriesPaint(p);
plot.setAxisLinePaint(axisColor);
JFreeChart chart = new JFreeChart("Spider Web Chart Demo 1"
, TextTitle.DEFAULT_FONT, plot, false);
LegendTitle legendtitle = new LegendTitle(plot);
legendtitle.setPosition(RectangleEdge.BOTTOM);
chart.addSubtitle(legendtitle);
return chart;
}
public static JPanel createDemoPanel() {
JFreeChart jfreechart = createChart(createDataset());
return new ChartPanel(jfreechart);
}
public static void main(String args[]) {
SpiderWebChartDemo1 spiderwebchartdemo1 = new SpiderWebChartDemo1("SpiderWebChartDemo1");
spiderwebchartdemo1.pack();
RefineryUtilities.centerFrameOnScreen(spiderwebchartdemo1);
spiderwebchartdemo1.setVisible(true);
}
}
I've seen gradient paint in bar charts, but not for spider charts. All I'm getting is transparent series.
Thanks.

You are setting the paint correctly however there are 2 things you should realize.
Gradient paints in java declare a start and end point. The first color will start at point 1 and transform into color 2 at point 2. If you use it to draw a polygon then the points are not relative to the polygons dimensions. Heres a picture to display, pt1 and pt2 in the picture are where your gradient start and end points are defined.
In an ideal world every setting is editable in a library but many times this just isnt the case. We can overcome that by overwriting methods in a subclass. You will need to override the SpiderWebPlot class and implement some of the painting methods. Heres a quick class I wrote up that does just that.
Take a look at the very end where it actually draws the polygon. I took this directly from the SpiderWebPlot source and altered the very end. To use this in your program call it like this
GradientSpiderWebPlot plot = new GradientSpiderWebPlot(categorydataset, Color.decode("#4282CE"), Color.decode("#9BC1FF"), .8f);
Here are the results
public class GradientSpiderWebPlot extends SpiderWebPlot {
private Color startColor, endColor;
private float alpha;
public GradientSpiderWebPlot(CategoryDataset data, Color startColor, Color endColor, float alpha) {
// TODO Auto-generated constructor stub
super(data);
this.startColor = startColor;
this.endColor = endColor;
this.alpha = alpha;
}
#Override
protected void drawRadarPoly(Graphics2D g2,
Rectangle2D plotArea,
Point2D centre,
PlotRenderingInfo info,
int series, int catCount,
double headH, double headW) {
Polygon polygon = new Polygon();
EntityCollection entities = null;
if (info != null) {
entities = info.getOwner().getEntityCollection();
}
// plot the data...
for (int cat = 0; cat < catCount; cat++) {
Number dataValue = getPlotValue(series, cat);
if (dataValue != null) {
double value = dataValue.doubleValue();
if (value >= 0) { // draw the polygon series...
// Finds our starting angle from the centre for this axis
double angle = getStartAngle()
+ (getDirection().getFactor() * cat * 360 / catCount);
// The following angle calc will ensure there isn't a top
// vertical axis - this may be useful if you don't want any
// given criteria to 'appear' move important than the
// others..
// + (getDirection().getFactor()
// * (cat + 0.5) * 360 / catCount);
// find the point at the appropriate distance end point
// along the axis/angle identified above and add it to the
// polygon
Point2D point = getWebPoint(plotArea, angle,
value / this.getMaxValue());
polygon.addPoint((int) point.getX(), (int) point.getY());
// put an elipse at the point being plotted..
Paint paint = getSeriesPaint(series);
Paint outlinePaint = getSeriesOutlinePaint(series);
Stroke outlineStroke = getSeriesOutlineStroke(series);
Ellipse2D head = new Ellipse2D.Double(point.getX()
- headW / 2, point.getY() - headH / 2, headW,
headH);
g2.setPaint(paint);
g2.fill(head);
g2.setStroke(outlineStroke);
g2.setPaint(outlinePaint);
g2.draw(head);
if (entities != null) {
int row = 0; int col = 0;
if (this.getDataExtractOrder() == TableOrder.BY_ROW) {
row = series;
col = cat;
}
else {
row = cat;
col = series;
}
String tip = null;
if (this.getToolTipGenerator() != null) {
tip = this.getToolTipGenerator().generateToolTip(
this.getDataset(), row, col);
}
String url = null;
if (this.getURLGenerator() != null) {
url = this.getURLGenerator().generateURL(this.getDataset(),
row, col);
}
Shape area = new Rectangle(
(int) (point.getX() - headW),
(int) (point.getY() - headH),
(int) (headW * 2), (int) (headH * 2));
CategoryItemEntity entity = new CategoryItemEntity(
area, tip, url, this.getDataset(),
this.getDataset().getRowKey(row),
this.getDataset().getColumnKey(col));
entities.add(entity);
}
}
}
}
// Plot the polygon
// Lastly, fill the web polygon if this is required
Rectangle2D rec = polygon.getBounds2D();
//Paint paint = getSeriesPaint(series);
// create linear vertical gradient based upon the bounds of the polygon.
Paint paint = new GradientPaint(new Point2D.Double(rec.getCenterX(),rec.getMinY()), startColor,
new Point2D.Double(rec.getCenterX(),rec.getMaxY()), endColor);
g2.setPaint(paint);
g2.setStroke(getSeriesOutlineStroke(series));
g2.draw(polygon);
if (this.isWebFilled()) {
// made this the variable alpha instead of the fixed .1f
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
alpha));
g2.fill(polygon);
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
getForegroundAlpha()));
}
}
}

AffineTransform.rotate() - how do I xlate, rotate, and scale at the same time?

I have the following code which does (the first part of) what I want drawing a chessboard with some pieces on it.
Image pieceImage = getImage(currentPiece);
int pieceHeight = pieceImage.getHeight(null);
double scale = (double)side/(double)pieceHeight;
AffineTransform transform = new AffineTransform();
transform.setToTranslation(xPos, yPos);
transform.scale(scale, scale);
realGraphics.drawImage(pieceImage, transform, this);
that is, it gets a chess piece's image and the image's height, it translates the drawing of that image to the square the piece is on and scales the image to the size of the square.
Llet's say I want to rotate the black pieces 180 degrees. Somewhere I expect to have something like:
transform.rotate(Math.toRadians(180) /* ?, ? */);
But I can't figure out what to put in as X and Y. If I put nothing, the image is nicely rotated around the 0,0 point of its chessboard square, putting the piece upside down in the square to the northeast of where it is supposed to be. I've guessed at various other combinations of x,y, with no luck yet.
I am already using translation to put the piece in the right square, the rotation transform wants another x,y around which to rotate things, but I don't know how to tell the transform to rotate the piece around one x,y and write the image to a different x,y. Can someone help me with the rotation parameters, or point me to something that explains how these things work? I've found examples of things that don't explain how they work, and so far I haven't figured out how to alter them to my situation...
Major edit: addition of working code. Sorry, I don't know how to post images, please substitute your own.
When I run the following I get a 2x2 chess board with a rook at the top left and a knight at the bottom right.
If I go into SmallChessboardComponent and take the comment delims off the first rotation transform statement, I get the rook in its original place upside down and the knight does not appear. If I instead take the comment delims off the second transform statement, neither piece appears at all.
I am looking for a way to turn the pieces upside down on the square on which they would appear anyway. I want to draw each piece onto the board; I don't want code that flips the board.
main program:
package main;
import java.awt.BorderLayout;
import javax.swing.JFrame;
import directredraw.SmallChessboardComponent;
public class SmallChessboardMain
{
private static void dbg (String message) { System.out.println(message); }
public static void main(String[] args)
{
//Create the top-level container and add contents to it.
final JFrame frame = new JFrame("Small Chessboard");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// create the chessboard itself and set it in the component
SmallChessboard chessboard = new SmallChessboard();
// create the GUI component that will contain the chessboard
SmallChessboardComponent chessboardComponent = new SmallChessboardComponent();
chessboardComponent.setBoard (chessboard);
frame.getContentPane().add(chessboardComponent, BorderLayout.CENTER);
// pack and display all this
frame.pack();
frame.setVisible(true);
}
}
chessboard class:
package main;
public class SmallChessboard
{
Piece [][] squares = new Piece[2][2];
public SmallChessboard()
{
squares[0][0] = new Piece(Piece.WHITECOLOR, Piece.ROOK);
squares[1][1] = new Piece(Piece.WHITECOLOR, Piece.KNIGHT);
}
/**
* get the piece at the given rank and file; null if
* no piece exists there.
*/
public Piece getPiece(int rank, int file)
{
if (0 > rank || rank > 2 || 0 > file || file > 2) { return null; }
else { return squares[rank][file]; }
}
}
chessboard component class:
package directredraw;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;
import javax.swing.JPanel;
import main.Piece;
import main.PieceImages;
import main.SmallChessboard;
public class SmallChessboardComponent extends JPanel
{
private static final long serialVersionUID = 1L;
Color whiteSquareColor = Color.yellow;
Color blackSquareColor = Color.blue;
private static void dbg (String msg) { System.out.println(msg); }
private SmallChessboard chessboard = null;
// currently playing with rotating images; this affine transform
// should help
AffineTransform rotationTransform = null;
private final int DEFAULT_PREFERRED_SIDE = 400;
int wholeSide = DEFAULT_PREFERRED_SIDE;
int side = DEFAULT_PREFERRED_SIDE / 8;
public void setBoard (SmallChessboard givenBoard)
{ chessboard = givenBoard;
}
/**
* set either or both colors for this chessboard; if either of
* the arguments are null, they do not change the existing color
* setting.
*/
public void setColors (Color darkSquare, Color lightSquare)
{
if (darkSquare != null) { blackSquareColor = darkSquare; }
if (lightSquare != null) { whiteSquareColor = lightSquare; }
}
/**
* return the preferred size for this component.s
*/
public Dimension getPreferredSize()
{ return new Dimension(wholeSide, wholeSide);
}
/*
* return the image object for the given piece
*/
private Image getImage(Piece piece)
{ return PieceImages.getPieceImage(this, piece);
}
public void paintComponent (Graphics graphics)
{
Graphics2D realGraphics = (Graphics2D) graphics;
// the image container might have been stretched.
// calculate the largest square held by the current container,
// and then 1/2 of that size for an individual square.
int wholeWidth = this.getWidth();
int wholeHeight = this.getHeight();
wholeSide = (wholeWidth / 2) * 2;
if (wholeHeight < wholeWidth) { wholeSide = (wholeHeight / 2) * 2; }
side = wholeSide / 2;
Rectangle clip = realGraphics.getClipBounds();
boolean firstColumnWhite = false;
// for each file on the board:
// set whether top square is white
// set background color according to white/black square
//
for (int fileIndex=0; fileIndex<8; fileIndex++)
{ boolean currentColorWhite = firstColumnWhite;
firstColumnWhite = !firstColumnWhite;
// draw the board and all the pieces
int rankIndex = 2;
for (rankIndex=2; rankIndex>=0; rankIndex--)
{
currentColorWhite = !currentColorWhite;
// x and y position of the top left corner of the square we're drawing,
// and rect becomes the dimensions and position of the square itself.
int xPos = fileIndex * side;
int yPos = rankIndex * side;
Rectangle rect = new Rectangle(xPos, yPos, side, side);
// if this square intersects the clipping rectangle we're drawing,
// then we'll draw the square and the piece on the square.
if (rect.intersects(clip))
{
// this puts down the correct color of square
if (currentColorWhite) { realGraphics.setColor(whiteSquareColor); }
else { realGraphics.setColor(blackSquareColor); }
realGraphics.fillRect(xPos, yPos, side, side);
// if there is a piece on this square and it isn't selected at the
// moment, then draw it.
Piece currentPiece = chessboard.getPiece(rankIndex, fileIndex);
if (currentPiece != null)
{
Image pieceImage = getImage(currentPiece);
int pieceHeight = pieceImage.getHeight(null);
double scalePiece = (double)side/(double)pieceHeight;
AffineTransform transform = new AffineTransform();
// transform.setToRotation(Math.toRadians(180));
transform.setToRotation(Math.toRadians(180), side/2, side/2);
transform.scale(scalePiece, scalePiece);
transform.translate(xPos/scalePiece, yPos/scalePiece);
// if (currentPiece.isBlack())
// {
// transform.translate(xPos + (side+2), yPos + (side+2));
// transform.rotate(Math.toRadians(180) /*, ,*/ );
// }
// else
// {
// transform.translate(xPos, yPos);
// }
realGraphics.drawImage(pieceImage, transform, this);
}
}
}
}
}
}
Piece.java
package main;
public class Piece
{
// piece types; the sum of the piece type and the
// color gives a number unique to both type and color,
// which is used for things like image indices.
public static final int PAWN = 0;
public static final int KNIGHT = 1;
public static final int BISHOP = 2;
public static final int ROOK = 3;
public static final int QUEEN = 4;
public static final int KING = 5;
// one of these is the color of the current piece
public static final int NOCOLOR = -1;
// the sum of the piece type and the
// color gives a number unique to both type and color,
// which is used for things like image indices.
public static final int BLACKCOLOR = 0;
public static final int WHITECOLOR = 6;
int color = NOCOLOR;
int imageIndex;
public Piece(int color, int pieceType)
{
// dbg -- all pieces are white rooks for now...
this.color = color;
imageIndex = color + pieceType;
}
/**
* return the integer associated with this piece's color;
*/
int getPieceColor()
{ return color;
}
/**
* return true if the piece is black
*/
public boolean isBlack()
{
return (color == BLACKCOLOR);
}
/**
* set the color associated with this piece; constants
* found in this class.
*/
public void setPieceColor(int givenColor)
{ color = givenColor;
}
/**
* return the integer designated for the image used for this piece.
*/
int getImageIndex()
{ return imageIndex;
}
}
and PieceImages.java
package main;
import java.awt.Component;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.net.URL;
public class PieceImages
{ static Image images[] = null;
private static void dbg (String msg) { System.out.println(msg); }
public static Image getPieceImage (Component target, Piece piece)
{
if (images == null)
try
{
MediaTracker tracker = new MediaTracker(target);
images = new Image[12];
images[Piece.BLACKCOLOR + Piece.PAWN] = getImage(tracker, "bPawn.gif");
images[Piece.BLACKCOLOR + Piece.KNIGHT] = getImage(tracker, "bKnight.gif");
images[Piece.BLACKCOLOR + Piece.BISHOP] = getImage(tracker, "bBishop.gif");
images[Piece.BLACKCOLOR + Piece.ROOK] = getImage(tracker, "bRook.gif");
images[Piece.BLACKCOLOR + Piece.QUEEN] = getImage(tracker, "bQueen.gif");
images[Piece.BLACKCOLOR + Piece.KING] = getImage(tracker, "bKing.gif");
images[Piece.WHITECOLOR + Piece.PAWN] = getImage(tracker, "wPawn.gif");
images[Piece.WHITECOLOR + Piece.KNIGHT] = getImage(tracker, "wKnight.gif");
images[Piece.WHITECOLOR + Piece.BISHOP] = getImage(tracker, "wBishop.gif");
images[Piece.WHITECOLOR + Piece.ROOK] = getImage(tracker, "wRook.gif");
images[Piece.WHITECOLOR + Piece.QUEEN] = getImage(tracker, "wQueen.gif");
images[Piece.WHITECOLOR + Piece.KING] = getImage(tracker, "wKing.gif");
if (!tracker.waitForAll(10000))
{ System.out.println("ERROR: not all piece main.images loaded");
}
dbg("piece images loaded");
}
catch (Exception xcp)
{ System.out.println("Error loading images");
xcp.printStackTrace();
}
return images[piece.getImageIndex()];
}
private static Image getImage(MediaTracker tracker, String file)
{
URL url = PieceImages.class.getResource("images/" + file);
Image image = Toolkit.getDefaultToolkit().getImage(url);
tracker.addImage(image, 1);
return image;
}
}

Okay, this is a little slight of hand. The example code will only work for 90 degree increments (it was only designed this way), to do smaller increments you to use some trig to calculate the image width and height (there's a answer somewhere for that to ;))
public class ImagePane extends JPanel {
private BufferedImage masterImage;
private BufferedImage renderedImage;
public ImagePane(BufferedImage image) {
masterImage = image;
applyRotation(0);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(renderedImage.getWidth(), renderedImage.getHeight());
}
#Override
public Dimension getMinimumSize() {
return getPreferredSize();
}
protected int getVirtualAngle(int angle) {
float fRotations = (float) angle / 360f;
int rotations = (int) (fRotations - (fRotations / 1000));
int virtual = angle - (rotations * 360);
if (virtual < 0) {
virtual = 360 + virtual;
}
return virtual;
}
public void applyRotation(int angle) {
// This will only work for angles of 90 degrees...
// Normalize the angle to make sure it's only between 0-360 degrees
int virtualAngle = getVirtualAngle(angle);
Dimension size = new Dimension(masterImage.getWidth(), masterImage.getHeight());
int masterWidth = masterImage.getWidth();
int masterHeight = masterImage.getHeight();
double x = 0; //masterWidth / 2.0;
double y = 0; //masterHeight / 2.0;
switch (virtualAngle) {
case 0:
break;
case 180:
break;
case 90:
case 270:
size = new Dimension(masterImage.getHeight(), masterImage.getWidth());
x = (masterHeight - masterWidth) / 2.0;
y = (masterWidth - masterHeight) / 2.0;
break;
}
renderedImage = new BufferedImage(size.width, size.height, masterImage.getTransparency());
Graphics2D g2d = renderedImage.createGraphics();
AffineTransform at = AffineTransform.getTranslateInstance(x, y);
at.rotate(Math.toRadians(virtualAngle), masterWidth / 2.0, masterHeight / 2.0);
g2d.drawImage(masterImage, at, null);
g2d.dispose();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
int width = getWidth() - 1;
int height = getHeight() - 1;
int x = (width - renderedImage.getWidth()) / 2;
int y = (height - renderedImage.getHeight()) / 2;
g2d.drawImage(renderedImage, x, y, this);
}
}
Now, you could simply "flip" the image vertically, if that works better for you
public class FlipPane extends JPanel {
private BufferedImage masterImage;
private BufferedImage renderedImage;
public FlipPane(BufferedImage image) {
masterImage = image;
flipMaster();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(renderedImage.getWidth(), renderedImage.getHeight());
}
#Override
public Dimension getMinimumSize() {
return getPreferredSize();
}
protected void flipMaster() {
renderedImage = new BufferedImage(masterImage.getWidth(), masterImage.getHeight(), masterImage.getTransparency());
Graphics2D g2d = renderedImage.createGraphics();
g2d.setTransform(AffineTransform.getScaleInstance(1, -1));
g2d.drawImage(masterImage, 0, -masterImage.getHeight(), this);
g2d.dispose();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
int width = getWidth() - 1;
int height = getHeight() - 1;
int x = (width - renderedImage.getWidth()) / 2;
int y = (height - renderedImage.getHeight()) / 2;
g2d.drawImage(renderedImage, x, y, this);
}
}
This basically results in:
Original | 180 degree rotation | Vertical inversion...
Now, if you change the flipMaster method to read:
g2d.setTransform(AffineTransform.getScaleInstance(-1, -1));
g2d.drawImage(masterImage, -masterImage.getWidth(), -masterImage.getHeight(), this);
You'll get the same effect as the 180 rotation ;)

Try performing the rotation before translating it into the correct position. Simply reorder the transformations so that first you scale, then you rotate (around the center point of the image), and then you translate:
transform.scale(scale, scale);
transform.rotate(Math.PI, pieceWidth / 2, pieceHeight /2);
transform.translation(xPos, yPos);
By the way, the black pieces on a chess board usually aren't rotated. :)
Update
In what way does it not work? The solution I provided also also differs from your code in that scaling is performed before translating. You can try the rotating, translating, and then scaling.
I strongly suggest that you modify your code so that you can perform the translation last. If you do this, everything will become a lot less complicated. Once you have done so, you only have to scale once to automatically take care of the rotation.
transform.scale(scale, scale); // or transform.scale(scale, -scale); to rotate
transform.translate(xPos, yPos);