Hello I would like to prevent graphics drawing and drawing again but I don't know how to do, I just want my panel delete all painted graphics and restart with same code. I tried some methods posted here but no one does the job.
public class Main extends JPanel implements ActionListener {
Timer timer;
private double angle = 444;
private double scale = 1;
private double delta = 0.0001;
RoundRectangle2D.Float r = new RoundRectangle2D.Float();
int counter = 0;
public Main() {
timer = new Timer(55, this);
timer.start();
}
public void paint(Graphics g) {
counter++;
int h = getHeight();
int w = getWidth();
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(new Color(randomNumber(0, 155), randomNumber(0, 255),randomNumber(0, 155), randomNumber(0, 255)));
drawCircles(g2d, getWidth()/2, getHeight()/2, 250);
if(counter > 200){
g2d.clearRect (0, 0, getWidth(), getHeight());
super.paintComponent(g2d);
counter = 0;
}
}
public int randomNumber(int min, int max) {
int c = new Random().nextInt((max - min) + 1);
return c;
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setUndecorated(true);
Dimension dim = new Dimension(Toolkit.getDefaultToolkit()
.getScreenSize().width, Toolkit.getDefaultToolkit()
.getScreenSize().height);
frame.setSize(dim);
frame.setLocation(0, 0);
frame.setBackground(new Color(0, 0, 0, 255));
frame.add(new Main());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
void drawCircles(Graphics graphics, int xMid, int yMid, int radius) {
// end recursion
if(radius < 5)
return;
// Draw circle
// start recursion
//left
drawCircles(graphics, xMid-radius, yMid, radius / 2);
((Graphics2D) graphics).rotate(angle);
graphics.drawOval(xMid - radius, yMid - radius, radius * 2, radius * 2);
//right
drawCircles(graphics, xMid+radius, yMid, radius / 2);
graphics.drawOval(xMid - radius, yMid - radius, radius * 2, radius * 2);
((Graphics2D) graphics).rotate(angle);
((Graphics2D) graphics).rotate(angle);
((Graphics2D) graphics).setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
((Graphics2D) graphics).setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
}
public void actionPerformed(ActionEvent e) {
if (scale < 0.01)
delta = -delta;
else if (scale > 0.99)
delta = -delta;
scale += delta;
angle += 0.001;
repaint();
}
}
I am not sure I understand you fully, but you can use a JToggleButton (for example) where is the toggle button is down it prevents drawing. I can see something like this inside your drawCircles() method:
void drawCircles(Graphics graphics, int xMid, int yMid, int radius)
{
if(!toggleBtn.isSelected() // the toggle button is pressed
{
// draw something
}
}
In your example, you are drawing two circles and two ovals. If I understood you correctly, you want to be able to pause in the middle of the method, for example, and only draw the first circle. Then, at some point, you want to continue drawing the two ovals and the remaining circle. Unfortunately, you cannot do that. You cannot stop (or pause) a method in the middle of it.
Methods have to execute to completion (whether to the end, or an exception is thrown). However, you can create some kind of task to draw ONE shape (for example, a circle). If you create multiple tasks, you can draw many circles. To accomplish this, you will need to learn about Concurrency and probably about Java Tasks. You can have these tasks execute in some kind of order and because of concurrency, you could pause and resume these drawing tasks the way I think you would want.
Related
I'm quite new to Java and want to program an easy sun system where the moon rotates around the earth and the earth around the sun.
Everything works well except the moon doesn't want to move correctly :/
Because the earth diverges from the moon's initial position, the rotation radius of the moon grows accordingly to that distance. And again when the earth gets closer to the moons inertial position, the rotation radius decreases.
If the initial position is (0;0), it works but the moon hits the sun...
So how can I keep the distance between earth and moon constant?
I'm using AffineTransforms and here is a snippet of my code ;)
Thanks in advance!
Ellipse2D.Double MoonFrame = new Ellipse2D.Double(orbitEarth + orbitMoon - radiusMoon, -radiusMoon, radiusMoon*2, radiusMoon*2);
for (int i = 0; i < 360; i++)
{
theta += Math.PI/30;
AffineTransform TransformMoon = AffineTransform.getRotateInstance(theta,TransformEarth.getTranslateX(),TransformEarth.getTranslateY());
g2d.fill(TransformMond.createTransformedShape(MoonFrame));
}
So, your basic question comes down to "how do I find a point on a circle for a give angle" ... seriously, it's that simple
Based on many hours of googling and trial and error, I basically use the following, more or less.
protected Point pointOnCircle() {
double rads = Math.toRadians(orbitAngle - 180); // Make 0 point out to the right...
int fullLength = Math.round((outterRadius));
// Calculate the outter point of the line
int xPosy = Math.round((float) (Math.cos(rads) * fullLength));
int yPosy = Math.round((float) (Math.sin(rads) * fullLength));
return new Point(xPosy, yPosy);
}
The rest basically comes down to properly handling the compounding nature of transformations,
Basically, this takes a base Graphics context, applies the translation to it (the Earth's position) and creates two other contexts off it to apply additional transformations, one for the Earth and one for the moon...
Graphics2D g2d = (Graphics2D) g.create();
int yPos = (getHeight() - size) / 2;
// Transform the offset
g2d.transform(AffineTransform.getTranslateInstance(xPos, yPos));
Graphics2D earthG = (Graphics2D) g2d.create();
// Rotate around the 0x0 point, this becomes the center point
earthG.transform(AffineTransform.getRotateInstance(Math.toRadians(angle)));
// Draw the "earth" around the center point
earthG.drawRect(-(size / 2), -(size / 2), size, size);
earthG.dispose();
// Removes the last transformation
Graphics2D moonG = (Graphics2D) g2d.create();
// Calclate the point on the circle - based on the outterRadius or
// distance from the center point of the earth
Point poc = pointOnCircle();
int moonSize = size / 2;
// This is only a visial guide used to show the position of the earth
//moonG.drawOval(-outterRadius, -outterRadius, outterRadius * 2, outterRadius * 2);
moonG.fillOval(poc.x - (moonSize / 2), poc.y - (moonSize / 2), moonSize, moonSize);
moonG.dispose();
g2d.dispose();
And because I know how much that would have you scratching your head, a runnable example...
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private double angle;
private double orbitAngle;
private int xPos = 0;
private int size = 20;
private int outterRadius = size * 2;
private int delta = 2;
public TestPane() {
new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
xPos += delta;
if (xPos + size >= getWidth()) {
xPos = getWidth() - size;
delta *= -1;
} else if (xPos < 0) {
xPos = 0;
delta *= -1;
}
angle += 4;
orbitAngle -= 2;
repaint();
}
}).start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 200);
}
protected Point pointOnCircle() {
double rads = Math.toRadians(orbitAngle - 180); // Make 0 point out to the right...
int fullLength = Math.round((outterRadius));
// Calculate the outter point of the line
int xPosy = Math.round((float) (Math.cos(rads) * fullLength));
int yPosy = Math.round((float) (Math.sin(rads) * fullLength));
return new Point(xPosy, yPosy);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int yPos = (getHeight() - size) / 2;
// Transform the offset
g2d.transform(AffineTransform.getTranslateInstance(xPos, yPos));
Graphics2D earthG = (Graphics2D) g2d.create();
// Rotate around the 0x0 point, this becomes the center point
earthG.transform(AffineTransform.getRotateInstance(Math.toRadians(angle)));
// Draw the "earth" around the center point
earthG.drawRect(-(size / 2), -(size / 2), size, size);
earthG.dispose();
// Removes the last transformation
Graphics2D moonG = (Graphics2D) g2d.create();
// Calclate the point on the circle - based on the outterRadius or
// distance from the center point of the earth
Point poc = pointOnCircle();
int moonSize = size / 2;
// This is only a visial guide used to show the position of the earth
//moonG.drawOval(-outterRadius, -outterRadius, outterRadius * 2, outterRadius * 2);
moonG.fillOval(poc.x - (moonSize / 2), poc.y - (moonSize / 2), moonSize, moonSize);
moonG.dispose();
g2d.dispose();
}
}
}
This moves a "Earth" object, which is rotating in one direction and then rotates the moon around it, in the opposite direction
You can simplify your math by concatenating transforms. Work backwards from the last transform to the first, or use preConcatenate to build them in a more natural order.
Compose complex transforms from simple transforms, for example by building an orbital transform from a translate and a rotate:
// Earth transform.
// Set the orbital radius to 1/3rd the panel width
AffineTransform earthTx = AffineTransform.getTranslateInstance(getWidth() / 3, 0);
// Rotate
earthTx.preConcatenate(AffineTransform.getRotateInstance(angle));
Later transforms (e.g. the moon orbiting the earth) can then be built on top of earlier results:
// Moon transform.
// Set the orbital radius to 1/10th the panel width
AffineTransform moonTx = AffineTransform.getTranslateInstance(getWidth() / 10, 0);
// Rotate
moonTx.preConcatenate(AffineTransform.getRotateInstance(angle));
// Add the earth transform
moonTx.preConcatenate(earthTx);
Full example:
public class Orbit {
public static class OrbitPanel extends JComponent {
int width;
int height;
public OrbitPanel(int width, int height) {
this.width = width;
this.height = height;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(width, height);
}
#Override
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// Clear the background.
g2.setColor(getBackground());
g2.fillRect(0, 0, getWidth(), getHeight());
// Sun transform. Just centre it in the window.
AffineTransform sunTx = AffineTransform.getTranslateInstance(getWidth() / 2, getHeight() / 2);
// Draw the sun
g2.setTransform(sunTx);
drawBody(g2, 30, Color.YELLOW);
// Orbital period.
// One rotation every 10s.
double percentRotation = System.currentTimeMillis() % 10000 / 10000.0;
// To radians.
double angle = Math.PI * 2 * percentRotation;
// Earth transform.
// Set the orbital radius to 1/3rd the panel width
AffineTransform earthTx = AffineTransform.getTranslateInstance(getWidth() / 3, 0);
// Rotate
earthTx.preConcatenate(AffineTransform.getRotateInstance(angle));
// Add the sun transform
earthTx.preConcatenate(sunTx);
// Draw the earth
g2.setTransform(earthTx);
drawBody(g2, 10, Color.BLUE);
// Moon transform.
// Set the orbital radius to 1/10th the panel width
AffineTransform moonTx = AffineTransform.getTranslateInstance(getWidth() / 10, 0);
// Rotate
moonTx.preConcatenate(AffineTransform.getRotateInstance(angle));
// Add the earth transform (already includes the sun transform)
moonTx.preConcatenate(earthTx);
// Draw the moon
g2.setTransform(moonTx);
drawBody(g2, 5, Color.DARK_GRAY);
}
private void drawBody(Graphics2D g2, int size, Color color) {
g2.setColor(color);
g2.fillOval(-size / 2, -size / 2, size, size);
}
}
public static void main(String[] args) throws IOException, InterruptedException {
JFrame frame = new JFrame("Orbit");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
JComponent orbitPanel = new OrbitPanel(250, 250);
frame.add(orbitPanel);
frame.pack();
frame.setVisible(true);
while (true) {
Thread.sleep(20);
orbitPanel.repaint();
}
}
}
I am new in Java. I want to make simple agario game for my project. But I have a problem. I want to make random stopping circles on Panel but my circles don't stop and changing.
The Problem is I think Timer.
class TestPanel extends JPanel implements ActionListener{
TestPanel(){
Timer t = new Timer(50,this);
t.start();
}
Random rnd = new Random();
int r = rnd.nextInt(256);
int b = rnd.nextInt(256);
int gr = rnd.nextInt(256);
Color randomColor = new Color(r,b,gr);
Ellipse2D.Double ball = new Ellipse2D.Double(0, 0, 40, 40);
double v = 10;
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 =(Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(Color.RED);
g2.fill(ball);
int NumOfCircles = 70;
int diameter;
int x, y;
Graphics2D g3 =(Graphics2D)g;
for(int count = 0; count < NumOfCircles; count++){
diameter = rnd.nextInt(10);
x = rnd.nextInt(600);
y = rnd.nextInt(620);
g3.setColor(randomColor);
g3.fillOval(x, y, diameter, diameter);
}
}
#Override
public void actionPerformed(ActionEvent arg0) {
Point p = getMousePosition();
if(p==null) return;
double dx = p.x - ball.x - 20;
double dy = p.y - ball.y - 20;
if(dx*dx+dy*dy >12){
double a=Math.atan2(dy, dx);
ball.x += v * Math.cos(a);
ball.y += v * Math.sin(a);}
repaint();
}
}
The problem is in your painting code. You can't control when Swing invokes the painting logic. So the painting code should only paint the object based on the properties of the panel and should not modify the properties.
This means:
Don't generate random values is a painting method.
In the constructor of your class you generate the Circles and assign a default size/location to each Circle. This information is then stored in in an ArrayList. Then in the paintComponent() method you simply iterate through the List and paint each circle.
In the ActionListener of the Timer you then itereate through the ArrayList and update the location of each Circle. Then you invoke repaint() on the panel so all the Circles get repainted.
For example check out: How to move two circles together in a JFrame from two different classes
Essentially, in this program bugs move around the screen eating food.
The issue that I am having is that graphics "circle" repaints fine and moves around the frame, but none of the bugs are repainted (However they are drawn initially).
I've tested it with console outputs and the x and y coordinates of the bugs do update, but the graphic in the frame does not.
So my question is, why is it the x/y of the circle is updated and repainted, but the bugs are not?
(As far as I can see, I'm approaching the task of changing the bugs x/y in the same way as with the circle)
(I've removed some of the things like the world getters and setters, and cut the code down a bit. The actual program has a movebug() method which handles the moving of the bugs in a correct fashion with hit detection.)
public class Run extends JPanel implements ActionListener{
double x, y, velX, velY, newx, newy;
public Timer t;
private static AWorld world1;
ArrayList<Ellipse2D> graphicBugArrayList = new ArrayList<Ellipse2D>();
public Run(){
x = 150;
y = 150;
velX = 2;
velY = 2;
t = new Timer(5, this);
setWorld1(new AWorld());
getWorld1().populatemap();
AWorld.direction directionchecker;
repaint();
t.start();
}
public void paintComponent(Graphics g){
//Creating circle that move
g.setColor(Color.BLACK);
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
Ellipse2D circle = new Ellipse2D.Double(x, y, 10, 10);
//creating and drawing the bugs
for(int i=0; i<world1.getNumberofbugs(); i++)
{
Ellipse2D obscircle = new Ellipse2D.Double(getWorld1().bugArrayList.get(i).getHPosition(), getWorld1().bugArrayList.get(i).getVPosition(), 14, 15);
graphicBugArrayList.add(obscircle);
g2.setPaint(Color.RED);
g2.fill(graphicBugArrayList.get(i));
g2.draw(graphicBugArrayList.get(i));
}
//Drawing the circle that moves
g2.setPaint(Color.BLACK);
g2.draw(circle);
}
public void actionPerformed(ActionEvent arg0) {
//Moving the circle
if(x<0 || x > 500)
{
velX = -velX;
}
if(y<0 || y > 500)
{
velY = -velY;
}
x += velX;
y -= velY;
//Test moving the bugs
getWorld1().bugArrayList.get(i).setHPosition(getWorld1().bugArrayList.get(i).getHPosition()+1);
repaint();
}
}
You never clear your graphicBugArrayList, but only draw the first few elements over and over. Try this in your loop:
for(int i=0; i<world1.getNumberofbugs(); i++)
{
Ellipse2D obscircle = new Ellipse2D.Double(getWorld1().bugArrayList.get(i).getHPosition(), getWorld1().bugArrayList.get(i).getVPosition(), 14, 15);
graphicBugArrayList.add(i, obscircle);
g2.setPaint(Color.RED);
g2.fill(graphicBugArrayList.get(i));
g2.draw(graphicBugArrayList.get(i));
}
I am trying to display two rotating wheels with diameter 512untis at different rates but i am not able to remove the previous drawn image graphics and set the rotated graphics at the correct position.
For now i am doing a rotation with arbitrary angle.
I tried affineTransform and got the rotations but it was weird like all pixels spread away.
Im using a while loop with thread.sleep(). The following is the code :
//The drawSmallCircle and drawBigCircle return two images.
class MyFramePart2 extends JFrame
{
String name;
JPanel big_obj_panel,small_obj_panel;
JLabel bigLabel,smallLabel;BufferedImage imgRet,imgRetSmall;
static double radians,angle,rev,fps,smallAngle,smallRadians;
int numLines,i=0;
MyFramePart2(String frameName,int numStrokes,double revolutions,double frameps)
{
numLines=numStrokes;
smallAngle=smallRadians=angle=radians=Math.toRadians(360/numLines);
rev=revolutions;
fps=frameps;
setSize(1240,720);
setLocation(0,0);
setLayout(null);
getContentPane().setBackground(Color.WHITE);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
big_obj_panel=new JPanel();
big_obj_panel.setLayout(null);
big_obj_panel.setSize(512,512);
big_obj_panel.setLocation(100,100);
big_obj_panel.setBackground(Color.white);
add(big_obj_panel);
imgRet=drawBigCircle();
bigLabel = new JLabel(new ImageIcon(imgRet));
bigLabel.setLayout(null);
bigLabel.setLocation(0,0);
bigLabel.setSize(512,512);
bigLabel.setOpaque(true);
bigLabel.setBackground(Color.white);
big_obj_panel.add(bigLabel);
small_obj_panel=new JPanel();
small_obj_panel.setLayout(null);
small_obj_panel.setSize(512,512);
small_obj_panel.setLocation(700,100);
small_obj_panel.setBackground(Color.white);
add(small_obj_panel);
imgRetSmall=drawSmallCircle();
smallLabel = new JLabel(new ImageIcon(imgRetSmall));
smallLabel.setLayout(null);
smallLabel.setLocation(0,0);
smallLabel.setSize(512,512);
smallLabel.setOpaque(true);
smallLabel.setBackground(Color.white);
small_obj_panel.add(smallLabel);
setVisible(true);
while(i!=5) // suppose to be while true, just checking
{
setVisible(true);
bigLabel.setIcon(new ImageIcon(imgRet));
smallLabel.setIcon(new ImageIcon(imgRetSmall));
try{
Thread.sleep(10);
}
catch(Exception e)
{}
i++;
}
}
#Override
public void paint(Graphics g)
{
super.paint(g);
Graphics2D g2d=(Graphics2D)g;
g2d.translate(256,256);
g2d.rotate(Math.toRadians(20));
g2d.translate(-256,-256);
g2d.drawImage(imgRet,0,0,null);
g2d.dispose();
super.paint(g);
g2d=(Graphics2D)g;
g2d.translate(256,256);
g2d.rotate(Math.toRadians(30));
g2d.translate(-256,-256);
g2d.drawImage(imgRetSmall,0,0,null);
g2d.dispose();
}
public static BufferedImage drawBigCircle()
{
BufferedImage img=new BufferedImage(512,512,BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d=img.createGraphics();
g2d.setColor(Color.black);
g2d.drawOval(0,0,511,511);
Line2D l2d;
while(angle <= 2*Math.PI)
{
l2d=new Line2D.Double(256,256,256+256*Math.cos(angle),256+256*Math.sin(angle));
g2d.draw(l2d);
angle=angle+radians;
}
return img;
}
}
First rule of Swing. Don't block the Event Dispatching Thread. Doing so will make you application look like it's hung and prevent the EDT from processing any repaint requests.
This means, you need some way to schedule updates that doesn't block the EDT
Second rule of Swing. Don't create or modify any UI component from any thread other then the EDT.
Generally, you should avoid overriding the paint method of top level containers like JFrame, apart from everything else, they're not double buffered, meaning your painting will flicker as it's updated. Instead, you should use one of the Swing containers, like JPanel
There are lots of different ways to achieve this. Basically, here I've used three lists, but if I was serious, I would create an object that could maintain all the required information (image, angle an delta)
In order to achieve the actual animation, I've used a javax.swing.Timer. This will trigger an event at least every n periods, but more importantly, it does it within the context of the Event Dispatching Thread. This ensures that all the changes made to the angles are done in way that will prevent any possibility of painting occurring while we're updating the values...
This example rotates the three images at different (random) speeds...
public class TestRotation {
public static void main(String[] args) {
new TestRotation();
}
public TestRotation() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new AnimationPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class AnimationPane extends JPanel {
private List<BufferedImage> images;
private List<Double> angles;
private List<Double> speed;
public AnimationPane() {
images = new ArrayList<>(5);
images.add(createWheel(50, 4));
images.add(createWheel(50, 3));
images.add(createWheel(50, 6));
angles = new ArrayList<>();
speed = new ArrayList<>();
for (int index = 0; index < images.size(); index++) {
angles.add(0d);
speed.add(Math.random() * 5d);
}
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
for (int index = 0; index < angles.size(); index++) {
double angle = angles.get(index);
double delta = speed.get(index);
angle += delta;
angles.set(index, angle);
}
repaint();
}
});
timer.setRepeats(true);
timer.setCoalesce(true);
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int x = 0;
int y = 0;
for (int index = 0; index < images.size(); index++) {
BufferedImage image = images.get(index);
double angle = angles.get(index);
// This is important. Basically we going to grab a isolated snap shot
// of the current graphics context. This means any changes we make
// will not affect the original graphics context (other then painting)
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
AffineTransform at = new AffineTransform();
at.translate(x, y);
at.rotate(Math.toRadians(angle), image.getWidth() / 2, image.getHeight() / 2);
g2d.setTransform(at);
g2d.drawImage(image, 0, 0, this);
g2d.dispose();
x += image.getWidth();
}
}
}
protected Point2D calculateOutterPoint(int radius, double angel) {
int x = Math.round(radius / 2);
int y = Math.round(radius / 2);
double rads = Math.toRadians((angel + 90));
// This determins the length of tick as calculate from the center of
// the circle. The original code from which this derived allowed
// for a varible length line from the center of the cirlce, we
// actually want the opposite, so we calculate the outter limit first
double fullLength = (radius / 2d);
// Calculate the outter point of the line
double xPosy = (x + Math.cos(rads) * fullLength);
double yPosy = (y - Math.sin(rads) * fullLength);
return new Point2D.Double(xPosy, yPosy);
}
public BufferedImage createWheel(int radius, int spokes) {
BufferedImage img = new BufferedImage(radius, radius, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(Color.black);
g2d.drawOval(0, 0, radius - 1, radius - 1);
Point2D center = new Point2D.Double(radius / 2d, radius / 2d);
double angle = 360d / spokes;
for (int index = 0; index < spokes; index++) {
Point2D p = calculateOutterPoint(radius, index * angle);
g2d.draw(new Line2D.Double(center, p));
}
g2d.dispose();
return img;
}
}
I am making a maze and I would like to use the recursive method as defined here. However, I need some help as to how to randomly open up the lines once I randomly draw them. Right now I'm creating the lines (walls of the maze) simply by drawing them with their beginning and end x- and y-coordinates. I just can't seem to find a simple way to "erase" (or "open up") parts of the lines.
EDIT: Okay I need to be slightly more specific. How could I randomly select places on each line to "open up?"
EDIT 2: Here is some code of what I'm trying to do:
public static void draw() {
// picks a random spot in the rectangle
Random r = new Random();
int x0 = r.nextInt(w)
int y0 = r.nextInt(h)
// draws the 4 lines that are perpendicular to each other and meet
// at the selected point
StdDraw.line(x0, 0, x0, y0);
StdDraw.line(0, y0, x0, y0);
StdDraw.line(x0, h, x0, y0);
StdDraw.line(w, y0, x0, y0);
}
public static void main(String[] args) {
// set up the walls of the maze
// given w = width and h = height
StdDraw.setXscale(0, w);
StdDraw.setYscale(0, h);
StdDraw.line(0, 0, 0, h);
StdDraw.line(0, h, w, h);
StdDraw.line(w, h, w, 0);
StdDraw.line(w, 0, 0, 0);
draw();
}
Now I just need to figure out how to randomly select 3 of these lines, and for each line randomly erase a portion.
Assuming you're using swing and the paintComponent method, you would set the Graphic's color to the background color and draw over the line again. Here's an example:
public class DrawTest extends JPanel{
public static void main(String[] args)
{
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DrawTest());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public Dimension getPreferredSize(){
return new Dimension(400,300);
}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.black);
g.drawLine(10, 10, 100, 10);
g.setColor(getBackground());
g.drawLine(50, 10, 60, 10);
}
}
EDIT
I suppose you're not creating the Maze in the paintComponent method (or you'd end up with a new maze every time you repainted). So, I'd recommend creating a sub-class similar to below and storing instances of it in an ArrayList field of your main class. Then you can iterate through your ArrayList when you're doing your panting.
public static class MazeWall{
public static final int OpeningWidth = 10;
Point start;
Point end;
Point opening;
public MazeWall(Point start, Point end, boolean hasOpening){
this.start = start;
this.end = end;
if(hasOpening){
int range;
if(start.x == end.x){
range = end.x - start.x - OpeningWidth;
int location = (int)(Math.random() * range + start.x);
opening = new Point(location, start.y);
} else{
range = end.y - start.y - OpeningWidth;
int location = (int)(Math.random() * range + start.y);
opening = new Point(location, start.x);
}
}
}
}