I have figured it out, thanks for the feedback Tanmay.
I noticed that the y-offset was incorrect for n - cols
and should be row - half
instead.
Below is the most comprehensive and compact code I could obtain. Although it is preferred to enter an odd integer for the size, you could enter a positive value. I also added a padding to the offset.
This if-conditional still troubles me: int xLbl = row < half ? col - row : col - half;
private void drawHexGridLoop(Graphics g, Point origin, int size, int radius, int padding) {
double ang30 = Math.toRadians(30);
double xOff = Math.cos(ang30) * (radius + padding);
double yOff = Math.sin(ang30) * (radius + padding);
int half = size / 2;
for (int row = 0; row < size; row++) {
int cols = size - java.lang.Math.abs(row - half);
for (int col = 0; col < cols; col++) {
int xLbl = row < half ? col - row : col - half;
int yLbl = row - half;
int x = (int) (origin.x + xOff * (col * 2 + 1 - cols));
int y = (int) (origin.y + yOff * (row - half) * 3);
drawHex(g, xLbl, yLbl, x, y, radius);
}
}
}
Main.java
import java.awt.*;
import javax.swing.*;
public class Main extends JPanel {
private static final long serialVersionUID = 1L;
private final int WIDTH = 1200;
private final int HEIGHT = 800;
private Font font = new Font("Arial", Font.BOLD, 18);
FontMetrics metrics;
public Main() {
setPreferredSize(new Dimension(WIDTH, HEIGHT));
}
@Override
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Point origin = new Point(WIDTH / 2, HEIGHT / 2);
g2d.setStroke(new BasicStroke(4.0f, BasicStroke.CAP_SQUARE, BasicStroke.JOIN_MITER));
g2d.setFont(font);
metrics = g.getFontMetrics();
drawCircle(g2d, origin, 380, true, true, 0x4488FF, 0);
drawHexGridLoop(g2d, origin, 7, 50, 8);
}
private void drawHexGridLoop(Graphics g, Point origin, int size, int radius, int padding) {
double ang30 = Math.toRadians(30);
double xOff = Math.cos(ang30) * (radius + padding);
double yOff = Math.sin(ang30) * (radius + padding);
int half = size / 2;
for (int row = 0; row < size; row++) {
int cols = size - java.lang.Math.abs(row - half);
for (int col = 0; col < cols; col++) {
int xLbl = row < half ? col - row : col - half;
int yLbl = row - half;
int x = (int) (origin.x + xOff * (col * 2 + 1 - cols));
int y = (int) (origin.y + yOff * (row - half) * 3);
drawHex(g, xLbl, yLbl, x, y, radius);
}
}
}
private void drawHex(Graphics g, int posX, int posY, int x, int y, int r) {
Graphics2D g2d = (Graphics2D) g;
Hexagon hex = new Hexagon(x, y, r);
String text = String.format("%s : %s", coord(posX), coord(posY));
int w = metrics.stringWidth(text);
int h = metrics.getHeight();
hex.draw(g2d, x, y, 0, 0x008844, true);
hex.draw(g2d, x, y, 4, 0xFFDD88, false);
g.setColor(new Color(0xFFFFFF));
g.drawString(text, x - w/2, y + h/2);
}
private String coord(int value) {
return (value > 0 ? "+" : "") + Integer.toString(value);
}
public void drawCircle(Graphics2D g, Point origin, int radius,
boolean centered, boolean filled, int colorValue, int lineThickness) {
// Store before changing.
Stroke tmpS = g.getStroke();
Color tmpC = g.getColor();
g.setColor(new Color(colorValue));
g.setStroke(new BasicStroke(lineThickness, BasicStroke.CAP_ROUND,
BasicStroke.JOIN_ROUND));
int diameter = radius * 2;
int x2 = centered ? origin.x - radius : origin.x;
int y2 = centered ? origin.y - radius : origin.y;
if (filled)
g.fillOval(x2, y2, diameter, diameter);
else
g.drawOval(x2, y2, diameter, diameter);
// Set values to previous when done.
g.setColor(tmpC);
g.setStroke(tmpS);
}
public static void main(String[] args) {
JFrame f = new JFrame();
Main p = new Main();
f.setContentPane(p);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
Hexagon.java
import java.awt.*;
public class Hexagon extends Polygon {
private static final long serialVersionUID = 1L;
public static final int SIDES = 6;
private Point[] points = new Point[SIDES];
private Point center = new Point(0, 0);
private int radius;
private int rotation = 90;
public Hexagon(Point center, int radius) {
npoints = SIDES;
xpoints = new int[SIDES];
ypoints = new int[SIDES];
this.center = center;
this.radius = radius;
updatePoints();
}
public Hexagon(int x, int y, int radius) {
this(new Point(x, y), radius);
}
public int getRadius() {
return radius;
}
public void setRadius(int radius) {
this.radius = radius;
updatePoints();
}
public int getRotation() {
return rotation;
}
public void setRotation(int rotation) {
this.rotation = rotation;
updatePoints();
}
public void setCenter(Point center) {
this.center = center;
updatePoints();
}
public void setCenter(int x, int y) {
setCenter(new Point(x, y));
}
private double findAngle(double fraction) {
return fraction * Math.PI * 2 + Math.toRadians((rotation + 180) % 360);
}
private Point findPoint(double angle) {
int x = (int) (center.x + Math.cos(angle) * radius);
int y = (int) (center.y + Math.sin(angle) * radius);
return new Point(x, y);
}
protected void updatePoints() {
for (int p = 0; p < SIDES; p++) {
double angle = findAngle((double) p / SIDES);
Point point = findPoint(angle);
xpoints[p] = point.x;
ypoints[p] = point.y;
points[p] = point;
}
}
public void draw(Graphics2D g, int x, int y, int lineThickness, int colorValue, boolean filled) {
// Store before changing.
Stroke tmpS = g.getStroke();
Color tmpC = g.getColor();
g.setColor(new Color(colorValue));
g.setStroke(new BasicStroke(lineThickness, BasicStroke.CAP_SQUARE, BasicStroke.JOIN_MITER));
if (filled)
g.fillPolygon(xpoints, ypoints, npoints);
else
g.drawPolygon(xpoints, ypoints, npoints);
// Set values to previous when done.
g.setColor(tmpC);
g.setStroke(tmpS);
}
}