We Keep Coding

Circle to Circle collision in Java

So I am doing circle to circle collision in java. I am aware that there are many similiar questions like mine on this website but my problem is unique from all of them. When I run my code, the circle's collide with each other once every 4 times. Meaning: 3 times they will go through without colliding with one another but one time they will collide. Any help is greatly appreciated.
public class Ball {
float x, y; // coordinates of ball rectangle
float xo, yo;
float vx = 2, vy = 2; // coordinates of velocity vector
Color colour; // ball colour
float d; // diameter of the ball or sizes of ball rectangle
Ellipse2D.Float circle;
// overloaded constructor
Ball(int x, int y, int vx, int vy, int d, Color colour) {
this.x = x;
this.y = y;
this.d = d;
xo = x;
yo = y;
this.setColour(colour);
this.setVelocity(vx, vy);
circle = new Ellipse2D.Float(x, y, d, d);
}
public void setColour(Color colour) {
this.colour = colour;
}
public void setVelocity(int vx, int vy) {
this.vx = vx;
this.vy = vy;
}
public void show(Graphics g) {
((Graphics2D) g).setPaint(colour);
circle.setFrame(x, y, d, d);
((Graphics2D) g).fill(circle);
xo = x;
yo = y;
}
public void hide(Graphics g) {
Color c = ((Graphics2D) g).getBackground();
((Graphics2D) g).setPaint(c);
circle.setFrame(xo, yo, d, d);
((Graphics2D) g).fill(circle);
}
public void setPosition(float x, float y) {
this.x = x;
this.y = y;
}
public void move(int a, int b, int xh, int yh) {
if (vy > 0) {
if (y + d + vy - yh - b > 0) {
y = yh + b - d;
vy = -vy;
} else
y += vy;
} else {
if (y + vy <= b) {
y = b;
vy = -vy;
} else
y += vy;
}
if (vx > 0) {
if (x + d + vx - xh - a > 0) {
x = xh + a - d;
vx = -vx;
} else
x += vx;
} else {
if (x + vx <= a) {
x = a;
vx = -vx;
} else
x += vx;
}
}
The Collision Detector is in the class below
public class Game extends JFrame {
int ah, bh, xh, yh; // parameters of the rectangle frame
Color[] ColorAr = { Color.red, Color.blue, Color.pink, Color.green,
Color.yellow, Color.magenta, Color.black, Color.orange, Color.gray,
Color.cyan };
Ball b[];
int quantity = 4;
public void paint(Graphics g) {
int i;
((Graphics2D) g).setPaint(Color.black);
((Graphics2D) g).drawRect(ah, bh, xh, yh);
for (i = quantity - 1; i >= 0; i--) {
b[i].hide(g);
}
for (i = 0; i < quantity; i++) {
b[i].show(g);
}
}
public void prepare() {
int i;
ah = 20;
bh = 40;
xh = 400;
yh = 400;
b = new Ball[quantity];
for (i = 0; i < quantity; i++) {
b[i] = new Ball((int) (Math.random() * (300 - 1 + 1)) + 1, 100, 1,
1, 26, ColorAr[(int) (Math.random() * 9)]);
}
}
public void collision() {
int radius = 13;
int distance = 2 * radius;
if (b[1].x + distance == b[0].x && b[1].y == b[0].y
|| b[1].x - distance == b[0].x && b[1].y == b[0].y) {
b[1].vx = -b[1].vx;
b[0].vx = -b[0].vx;
}
}
public void run() {
int i;
while (true) {
for (i = 0; i < quantity; i++)
b[i].move(ah, bh, xh, yh);// move balls
collision();
for (int j = 0; j < 10000000; j++)
; // delay;
// collision();
repaint();
}
}
public static void main(String args[]) {
Game frame = new Game();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// frame.setBackground(Color.white);
frame.setSize(450, 470);
frame.prepare();
frame.setVisible(true);
frame.run();
}
}

For two circles:
First calculate the sum of lengths: radius_1 + radius_2 (the first and the second circle).
Collision of two circles can be detected if you calculate the length of (imaginary) line between centers. If THAT length <= radius_1 + radius_2, two circles are colliding.

How to trigger multiple MouseEvent events

I have a class that when clicked draws one point, when clicked again it draws another point and draws the line between them.
public class SlopeComponent extends JComponent
{
private static final long serialVersionUID = 1L;
public SlopeComponent()
{
point1 = null;
point2 = null;
class MouseSpy extends MouseAdapter
{
public void mousePressed(MouseEvent event)
{
double x1 = rxPixel(event.getX());
double y1 = ryPixel(event.getY());
point1 = new Point2D.Double(x1, y1);
double x2 = rxPixel(event.getX());
double y2 = ryPixel(event.getY());
point2 = new Point2D.Double(x2, y2);
repaint();
}
}
MouseSpy listener = new MouseSpy ();
addMouseListener(listener);
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
Axes axes = new Axes(xPixel(XMIN), xPixel(XMAX), yPixel(YMIN), yPixel(YMAX),
xPixel(0), yPixel(0), sWidth(1), sHeight(1));
axes.drawAxes(g2); //draw the axes
axes.drawTicks(g2);
if(point1 != null || point2 != null)
{
plotPoint(g2, point1);
plotPoint(g2, point2);
double x1 = point1.getX();
double y1 = point1.getY();
double x2 = point2.getX();
double y2 = point2.getY();
drawSlope(g2, x1, y1, x2, y2);
}
}
public void drawSlope(Graphics2D g2, double x1, double y1, double x2, double y2) //draw the lines
{
Point2D.Double p1 = new Point2D.Double(xPixel(x1), yPixel(y1));
Point2D.Double p2 = new Point2D.Double(xPixel(x2), yPixel(y2));
Line2D.Double line = new Line2D.Double(p1, p2);
g2.draw(line);
}
public void plotPoint(Graphics2D g2, Point2D.Double p) //plot the point
{
double x = p.getX();
double y = p.getY();
double radius = 5 * (XMAX - XMIN) / getWidth();
Ellipse2D.Double point = new Ellipse2D.Double(xPixel(x - radius), yPixel(y + radius),
sWidth(2 * radius), sHeight(2 * radius));
g2.fill(point);
double xR = Rounding.round(x, 1);
double yR = Rounding.round(y, 1);
double gap = 6 * (XMAX - XMIN) / getWidth();
g2.drawString("(" + xR + ", " + yR + ")", (float)xPixel(x + gap), (float)yPixel(y + gap));
}
public double rxPixel(double x)
{
return x * (XMAX - XMIN) / (getWidth() - 1) + XMIN;
}
public double ryPixel(double y)
{
return y * (YMIN - YMAX) / (getHeight() - 1) + YMAX;
}
public double xPixel(double xuser)
{
return (xuser - XMIN) * (getWidth() - 1) / (XMAX - XMIN);
}
public double yPixel(double yuser)
{
return (yuser - YMAX) * (getHeight() - 1) / (YMIN - YMAX);
}
public double sHeight(double yuser)
{
return yuser * (getHeight() - 1) / (YMAX - YMIN);
}
public double sWidth(double xuser)
{
return xuser * (getWidth() - 1) / (XMAX - XMIN);
}
private static final double XMIN = -10;
private static final double XMAX = 10;
private static final double YMIN = -10;
private static final double YMAX = 10;
private Point2D.Double point1;
private Point2D.Double point2;
}
However, when I try to run this, it draws both points on top of each other, then the line on top of that. I know that in my constructor I am calling getX() and getY() on the same event so that point1 and point2 have the coordinates. How do I call multiple events so that this does not happen.

You can count the clicks, you can do something like this
int count = 0;
public void mousePressed(MouseEvent event)
{
if(count == 0){
double x1 = rxPixel(event.getX());
double y1 = ryPixel(event.getY());
point1 = new Point2D.Double(x1, y1);
count++;
}
if(count == 1){
double x2 = rxPixel(event.getX());
double y2 = ryPixel(event.getY());
point2 = new Point2D.Double(x2, y2);
repaint();
}
}

Screen Snake Collision Issue

I am a self taught programmer and I am coding Screen Snake for fun. I am using not using integers to store the position of the snake or apples, I am using doubles. I am having an issue when the snake goes through the apple. When the collide, the code does not register that it collided. I am assuming that this is because their X and Y values might be like .1 off. I have been trying to fix this for 2 weeks but have not been able to. Sorry if my code is a bit messy. I don't know exactly what you guys need from the code so I posted all of it. Also I really appreciate the help! Thanks!!
Main class:
Random random = new Random();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double ScreenW = screenSize.getWidth();
double ScreenH = screenSize.getHeight();
int ScreenX = (int)Math.round(ScreenW);
int ScreenY = (int)Math.round(ScreenH);
JFrame frame = new JFrame();
double x = 1, y = 1;
int size = 5;
int ticks;
private int columnCount = 25;
private int rowCount = 15;
double a = (ScreenW / columnCount) - 1;
double b = (ScreenH / rowCount) - 1;
private Key key;
private List<Rectangle2D> cells;
private Point selectedCell;
boolean up = false;
boolean down = false;
boolean right = true;
boolean left = false;
boolean running = true;
private Thread thread;
private BodyP p;
private ArrayList<BodyP> snake;
private Apple apple;
private ArrayList<Apple> apples;
double width = screenSize.width;
double height = screenSize.height;
double cellWidth = width / columnCount;
double cellHeight = height / rowCount;
double xOffset = (width - (columnCount * cellWidth)) / 2;
double yOffset = (height - (rowCount * cellHeight)) / 2;
public Max_SnakeGame() throws IOException {
System.out.println(screenSize);
System.out.println(a + "," + b);
System.out.println(ScreenH + b);
System.out.println(ScreenW + a);
frame.getContentPane().add(new Screen());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setUndecorated(true);
frame.setBackground(new Color(0, 0, 0, 0));
frame.setLocationRelativeTo(null);
frame.setMaximumSize(screenSize);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
Image img = Toolkit
.getDefaultToolkit()
.getImage(
"C:/Users/Max/My Documents/High School/Sophomore year/Graphic Disign/People art/The Mods Who Tell Pointless Stories.jpg");
frame.setIconImage(img);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
try {
new Max_SnakeGame();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
public class Screen extends JPanel implements Runnable {
private static final long serialVersionUID = 1L;
public Screen() {
key = new Key();
addKeyListener(key);
setMaximumSize(screenSize);
setOpaque(false);
setBackground(new Color(0, 0, 0, 0));
setFocusable(true);
snake = new ArrayList<BodyP>();
apples = new ArrayList<>();
start();
}
public void start() {
running = true;
thread = new Thread(this);
thread.start();
}
public void run() {
while (running) {
MoveUpdate();
repaint();
}
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
repaint();
Graphics2D g2d = (Graphics2D) g.create();
cells = new ArrayList<>(columnCount * rowCount);
if (cells.isEmpty()) {
for (int row = 0; row < rowCount; row++) {
for (int col = 0; col < columnCount; col++) {
Rectangle2D cell = new Rectangle2D.Double(xOffset
+ (col * cellWidth), yOffset
+ (row * cellHeight), cellWidth, cellHeight);
cells.add(cell);
}
}
}
g2d.setColor(Color.GRAY);
for (Rectangle2D cell : cells) {
g2d.draw(cell);
}
for (int i = 0; i < snake.size(); i++) {
snake.get(i).draw(g);
}
for (int i = 0; i < apples.size(); i++) {
apples.get(i).draw(g);
}
}
}
private class Key implements KeyListener {
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
if (keyCode == KeyEvent.VK_RIGHT && !left) {
up = false;
down = false;
right = true;
}
if (keyCode == KeyEvent.VK_LEFT && !right) {
up = false;
down = false;
left = true;
}
if (keyCode == KeyEvent.VK_UP && !down) {
left = false;
right = false;
up = true;
}
if (keyCode == KeyEvent.VK_DOWN && !up) {
left = false;
right = false;
down = true;
}
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
}
public void MoveUpdate() {
if (snake.size() == 0) {
p = new BodyP(x, y, a, b);
snake.add(p);
}
if (apples.size() == 0){
double x1 = random.nextInt(25);
double Ax = ((x1*a+x1+1)*10)/10;
double y1 = random.nextInt(15);
double Ay = ((y1*b+y1+1)*10)/10;
double Afx = Math.round(Ax);
double Afy = Math.round(Ay);
System.out.println("Ax:"+Afx);
System.out.println("Ay:"+Afy);
apple = new Apple(Ax, Ay, a, b);
apples.add(apple);
}
for(int i = 0; i < apples.size(); i++) {
if(Math.round(x)-1 == apples.get(i).getx() || Math.round(x) == apples.get(i).getx() && Math.round(y)== apples.get(i).gety() || Math.round(y)-1 == apples.get(i).gety()) {
size++;
apples.remove(i);
i--;
}
}
ticks++;
if (ticks > 2500000) {
if (up == true) {
if (y <= 2) {
y = ScreenH - b;
System.out.println("Y:" + y);
} else {
y -= b + 1;
System.out.println("Y:" + y);
}
}
// down loop
else if (down == true) {
if (y >= ScreenH - b) {
y = 1;
System.out.println("Y:" + y);
}
else {
y += b + 1;
System.out.println("Y:" + y);
}
}
// left loop
else if (left == true) {
if (x <= 1) {
x = ScreenW - a;
System.out.println("X:" + x);
}
else {
x -= a + 1;
System.out.println("X:" + x);
}
}
// right loop
else if (right == true) {
if (x >= ScreenW - a) {
x = 1;
System.out.println("X:" + x);
}
else {
x += a + 1;
System.out.println("X:" + x);
}
}
ticks = 0;
p = new BodyP(x, y, a, b);
snake.add(p);
// rect.setFrame(x, y, a, b);
if (snake.size() > size) {
snake.remove(0);
}
}
}
}
Snake class:
public class BodyP {
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double ScreenW = screenSize.getWidth();
double ScreenH = screen`enter code here`Size.getHeight();
double x = 1, y = 1;
private int columnCount = 25;
private int rowCount = 15;
double a = (ScreenW / columnCount) - 1;
double b = (ScreenH / rowCount) - 1;
public BodyP(double x, double y, double a, double b) {
this.x = x;
this.y = y;
this.a = a;
this.b = b;
}
public void MoveUpdate(){
}
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
Rectangle2D rect = new Rectangle2D.Double(x, y, a, b);
g.setColor(Color.BLACK);
g2.fill(rect);
}
public double getx() {
return x;
}
public void setx(double x) {
this.x = x;
}
public double gety() {
return y;
}
public void sety(double y) {
this.y = y;
}
}
Apple class:
public class Apple {
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double ScreenW = screenSize.getWidth();
double ScreenH = screenSize.getHeight();
double x = 1, y = 1;
private int columnCount = 25;
private int rowCount = 15;
double a = (ScreenW / columnCount) - 1;
double b = (ScreenH / rowCount) - 1;
public Apple(double x, double y, double a, double b) {
this.x = x;
this.y = y;
this.a = a;
this.b = b;
}
public void MoveUpdate(){
}
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
Rectangle2D rect = new Rectangle2D.Double(x, y, a, b);
g.setColor(Color.RED);
g2.fill(rect);
}
public double getx() {
return x;
}
public void setx(double x) {
this.x = x;
}
public double gety() {
return y;
}
public void sety(double y) {
this.y = y;
}
}

If you think this is due rounding errors, use Euclidean distance and compare with the desired tolerance:
final double tolerance = 1.0; // or whatsoever
double dx = snake.x - apple.x;
double dy = snake.y - apple.y;
if ( dx*dx + dy*dy < tolearance * tolerance ) ...
I suggest to implement something like Point.distanceTo(Point) method to make this convenient.

Moving ball at an Angle

I am a newbie and trying to move a ball at a slope. Here is the code where I am giving coordinates (100,300,300,600) to move the ball in a slope but it's getting away from the the slope line. Here's the code: -
import javax.swing.*;
import java.awt.*;
public class AgentMotion extends JPanel implements Runnable
{
Color color = Color.red;
int dia = 0;
long delay = 40;
private double x;
private double y;
private double x1;
private double y1;
private int dx = 1;
private int dy = 1;
private int dv = 1;
private double direction;
double a;
double b;
double a1;
double b1;
public void abc(double x, double y, double x2, double y2) {
this.x = x;
this.y = y;
this.x1 = x2;
this.y1 = y2;
this.direction=Math.toRadians(Math.atan2(x1-x,y1-y));
System.out.println("segfewg"+direction);
this.a = x;
this.b = y;
this.a1 = x1;
this.b1 = y1;
}
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(color);
//int x=100;
//int y=200;
int x3=(int)this.x;
int y3=(int)this.y;
g.fillOval(x3,y3,5,5); // adds color to circle
g.setColor(Color.black);
g2.drawOval(x3,y3,5,5); // draws circle
g2.drawLine(100, 300, 300, 600);
}
public void run() {
if(direction<0)
{
System.out.println("refregreg");
while(dy!=0) {
try {
Thread.sleep(delay);
} catch(InterruptedException e) {
System.out.println("interrupted");
}
move2();
repaint();
move();
repaint();
}
}
else
{
while(dx!=0) {
try {
Thread.sleep(delay);
} catch(InterruptedException e) {
System.out.println("interrupted");
}
move2();
repaint();
move();
repaint();
}
}
}
public void move() {
if(direction>0)
{
if(x + dv*Math.cos(direction) <a ||x + dia + dv * Math.cos(direction) >b) {
dx *= 0;
color = getColor();
}
x += dx;
}
else
{
System.out.println(x + dia + dv * Math.cos(direction));
if(x + dia + dv * Math.cos(direction) >b) {
dx *= 0;
color = getColor();
}
x -= dx;
}
}
public void move2() {
if(direction>0)
{
if(dv * Math.sin(direction) + y <a1 || dv * Math.sin(direction) + dia + y > b1) {
dy *= 0;
color = getColor();
}
y += dy;
}
else
{
System.out.println(dv * Math.sin(direction) + dia + y);
if(dv * Math.sin(direction) + y <a1 || dv * Math.sin(direction) + dia + y < b1) {
dy *= 0;
color = getColor();
}
y -= dy;
}
}
public Color getColor() {
int rval = (int)Math.floor(Math.random() * 256);
int gval = (int)Math.floor(Math.random() * 256);
int bval = (int)Math.floor(Math.random() * 256);
return new Color(rval, gval, bval);
}
public void start() {
while(dx==0) {
try {
System.out.println("jiuj");
Thread.sleep(25);
} catch(InterruptedException e) {
System.out.println("dwdwdwd");
}
}
Thread thread = new Thread(this);
thread.setPriority(Thread.NORM_PRIORITY);
thread.start();
}
}

A few suggestions
dx and dy should be double
atan is overkill as #Spektre says. What you want is much more simple to calculate direction.
this.direction = (y2 - y) / (x2 - x)
If we give (100,300,300,600) as the arguments to abc (which would presumably be a constructor for this class), the slope is 1.5. Therefore we could say:
dx = 1.0
dy = 1.5
and this would keep on the line perfectly. For the general case where you want to change the begin and the end point, you have to calculate the ratio. So you could set either dx or dy to 1.0 and then set the other one so that the ratio is maintained. Something like the following mathematical pseudocode:
dx = (x2 - x) / minimum(x2-x, y2-y)
dy = (y2 - y) / minimum(x2-x, y2-y)

Calculate x y of Point after increasing distance

I am trying to get the x and y value of a point after increasing the distance r. Perhaps there is a better way of calculate the angle phi too, so that I don't need to check in which quadrant the point is. The 0-point is at the half of the width and height of the window. Here is my attempt:
package test;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
public final class Laser extends java.applet.Applet implements Runnable{
private static final long serialVersionUID = -7566644836595581327L;
Thread runner;
int width = 800;
int height = 600;
Point point = new Point(405,100);
Point point1 = new Point(405,100);
public void calc(){
int x = getWidth()/2;
int y = getHeight()/2;
int px = point.x;
int py = point.y;
int px1 = point1.x;
int py1 = point1.y;
double r = 0;
double phi = 0;
// Point is in:
// Quadrant 1
if(px > x && py < y){
r = Math.hypot(px1-x, y-py1);
phi = Math.acos((px1-x)/r)*(180/Math.PI);
}/*
// Quadrant 2
else if(px < x && py < y){
r = Math.hypot(x-px, y-py);
phi = Math.acos((px-x)/r)*(180/Math.PI);
}
// Quadrant 3
else if(px < x && py > y){
r = Math.hypot(x-px, py-y);
phi = Math.acos((px-x)/r)*(180/Math.PI)+180;
}
// Quadrant 4
else if(px > x && py > y){
r = Math.hypot(px-x, py-y);
phi = Math.acos((px-x)/r)*(180/Math.PI)+180;
}*/
r += 1;
point1.x = (int) (r*Math.cos(phi));
point1.y = (int) (r*Math.sin(phi));
System.out.println(r+";"+point1.x+";"+point1.y);
}
public void paint(Graphics g) {
g.setColor(Color.ORANGE);
calc();
g.drawLine(point.x, point.y, point1.x, point1.y);
int h = getHeight();
int w = getWidth();
g.setColor(Color.GREEN);
g.drawLine(0, h/2, w, h/2);
g.drawLine(w/2, 0, w/2, h);
}
/*
public void initPoints(){
for(int i = 0; i < pointsStart.length; i++){
int x = (int)(Math.random()*getWidth());
int y = (int)(Math.random()*getHeight());
pointsStart[i] = pointsEnd[i] = new Point(x,y);
}
}
*/
public void start() {
if (runner == null) {
runner = new Thread(this);
setBackground(Color.black);
setSize(width, height);
//initPoints();
runner.start();
}
}
#SuppressWarnings("deprecation")
public void stop() {
if (runner != null) {
runner.stop();
runner = null;
}
}
public void run() {
while (true) {
repaint();
try { Thread.sleep(700); }
catch (InterruptedException e) { }
}
}
public void update(Graphics g) {
paint(g);
}
}

You are changing (x,y) to be r from some other point, when it had previously been some distance r' from that point, correct? So why not avoid the trigonometry, and just scale each of the components from that point by r/r'?
Edit: ok, iterate over the pixels along whichever component (x or y) is longer (let's assume it's y); for each xi in (0..x), yi = xi*(y/x), and you plot (xi,yi).

Keep it simple! And use double variables for such computations, I changed it for you.
package test;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.geom.Point2D;
public final class Laser extends java.applet.Applet implements Runnable {
private static final long serialVersionUID = -7566644836595581327L;
Thread runner;
int width = 800;
int height = 600;
Point2D.Double point = new Point2D.Double(400, 100);
Point2D.Double point1 = new Point2D.Double(405, 102);
public void calc() {
double px = point.x;
double py = point.y;
double px1 = point1.x;
double py1 = point1.y;
double dx = px1 - px;
double dy = py1 - py;
double len = Math.hypot(dx, dy);
double newlen = len+2;
double coeff = Math.abs((newlen-len)/len);
point1.x += dx * coeff;
point1.y += dy * coeff;
System.out.println(len+";"+point1.x+";"+point1.y);
}
public void paint(Graphics g) {
g.setColor(Color.ORANGE);
calc();
g.drawLine((int)point.x, (int)point.y, (int)point1.x, (int)point1.y);
int h = getHeight();
int w = getWidth();
g.setColor(Color.GREEN);
g.drawLine(0, h / 2, w, h / 2);
g.drawLine(w / 2, 0, w / 2, h);
}
/*
* public void initPoints(){
*
* for(double i = 0; i < pointsStart.length; i++){ double x =
* (double)(Math.random()*getWidth()); double y =
* (double)(Math.random()*getHeight()); pointsStart[i] = pointsEnd[i] = new
* Point(x,y); }
*
* }
*/
public void start() {
if (runner == null) {
runner = new Thread(this);
setBackground(Color.black);
setSize(width, height);
// initPoints();
runner.start();
}
}
#SuppressWarnings("deprecation")
public void stop() {
if (runner != null) {
runner.stop();
runner = null;
}
}
public void run() {
while (true) {
repaint();
try {
Thread.sleep(700);
}
catch (InterruptedException e) {
}
}
}
public void update(Graphics g) {
paint(g);
}
}