import java.awt.*;
import java.applet.*;
public class solarSystem extends Applet {
private int height, width;
private solarSystemCanvas ssc;
private motion move;
public void init() {
//Get width and height of applet
width = Integer.parseInt(getParameter("width"));
height = Integer.parseInt(getParameter("height"));
setBackground(Color.black);
ssc = new solarSystemCanvas(width, height);
setLayout(new BorderLayout());
add("Center", ssc);
// a thread for animation
}
public void start() {
if (move == null) {
motion move = new motion(ssc);
move.start();
}
}
public void stop() {
if (move != null) {
move.stop();
move = null;
}
}
}
class solarSystemCanvas extends Canvas {
//Constants for numbers of items
static int NUM_STARS = 200;
static int NUM_PLANETS = 9;
static int NUM_ROIDS = 100;
//Constant names for planets in array
static int MERCURY = 0;
static int VENUS = 1;
static int EARTH = 2;
static int MARS = 3;
static int JUPITER = 4;
static int SATURN = 5;
static int URANUS = 6;
static int NEPTUNE = 7;
static int PLUTO = 8;
private int centerX, centerY;
private Star[] star;
private Graphics offgfx, bggfx;
private Image offimage, background;
private Planet[] planet, asteroid;
public solarSystemCanvas(int width, int height) {
//Find the Coordinates of the Center of Applet
this.centerX = width / 2;
this.centerY = height / 2;
//Initialize Stars
this.star = new Star[NUM_STARS];
for (int i = 0; i < NUM_STARS; i++) {
this.star[i] = new Star(width, height);
}
//Initialize Planets
this.planet = new Planet[NUM_PLANETS];
this.planet[MERCURY] = new Planet(4, 40, Color.cyan);
this.planet[VENUS] = new Planet(10, 60, Color.yellow);
this.planet[EARTH] = new Planet(10, 80, Color.blue);
this.planet[MARS] = new Planet(6, 100, Color.red);
this.planet[JUPITER] = new Planet(20, 140, Color.red);
this.planet[SATURN] = new Planet(18, 160, Color.magenta);
this.planet[URANUS] = new Planet(15, 180, Color.orange);
this.planet[NEPTUNE] = new Planet(15,200, Color.blue);
this.planet[PLUTO] = new Planet(4, 218, Color.green);
//Initialize Asteroids
this.asteroid = new Planet[NUM_ROIDS];
for (int i = 0; i < NUM_ROIDS; i++) {
this.asteroid[i] = new Planet((int)(Math.random() * 3) + 2,
110 + (int)(Math.random() * 20), Color.white);
}
//Position Objects
repaint();
}
public void update(Graphics g) {
//Create Background
if (background == null) {
background = createImage(centerX * 2, centerY * 2);
bggfx = background.getGraphics();
//Draw Stars
bggfx.setColor(Color.white);
for (int i = 0; i < NUM_STARS; i++) {
star[i].drawStar(bggfx);
}
//Draw Sun
circle(bggfx, Color.yellow, centerX, centerY, 50);
//Draw Planet Orbits
for (int i = 0; i < NUM_PLANETS; i++) {
planet[i].drawOrbit(bggfx, centerX, centerY);
}
}
//create double buffer
if (offgfx == null) {
offimage = createImage(centerX * 2, centerY * 2);
offgfx = offimage.getGraphics();
}
offgfx.drawImage(background, 0, 0, null);
//Draw Planets
for (int i = 0; i < NUM_PLANETS; i++) {
planet[i].movePlanet(centerX, centerY);
planet[i].drawPlanet(offgfx);
}
//Draw Asteroids
for (int i = 0; i < NUM_ROIDS; i++) {
asteroid[i].movePlanet(centerX, centerY);
asteroid[i].drawPlanet(offgfx);
}
g.drawImage(offimage, 0, 0, null);
}
public void circle(Graphics g, Color c, int x, int y, int radius) {
g.setColor(c);
g.fillOval(x - radius / 2, y - radius / 2, radius, radius);
}
public boolean mouseDown(Event e, int x, int y) {
//See if User Clicks on a Planet
for(int i = 0; i < NUM_PLANETS; i++) {
this.planet[i].testPlanet(x, y);
}
//See if User Clicks on the Sun
if ((x > centerX - 25) && (y > centerY - 25) &&
(x < centerX + 25) && (y < centerY + 25)) {
for(int i = 0; i < NUM_PLANETS; i++) {
this.planet[i].unBouncePlanet();
}
}
return super.mouseDown(e, x, y);
}
}
class Star {
private int x, y, size;
Star(int width, int height) {
this.x = (int)(Math.random() * (width - 2) + 1);
this.y = (int)(Math.random() * (height - 2) + 1);
this.size = (int)(Math.random() * 3 + 1);
}
public void drawStar(Graphics g) {
g.fillRect(this.x, this.y, this.size, this.size);
}
}
class Planet {
private static double pi = 3.141569;
private int size, distance;
private double radians, speed, x, y, xSpeed, ySpeed;
private boolean bounce;
private Color color;
Planet(int size, int distance, Color color) {
this.size = size;
this.distance = distance;
this.bounce = false;
this.color = color;
this.radians = Math.random() * 2 * pi;
this.speed = 2 * pi / distance ;
}
public void movePlanet(int centerX, int centerY) {
if (!(this.bounce)) {
//Orbit Planet around Sun
this.radians += speed;
this.x = Math.cos(this.radians) * distance + centerX - size / 2;
this.y = Math.sin(this.radians) * distance + centerY - size / 2;
}
else {
//Bounce Planet around Screen
this.x += xSpeed;
this.y += ySpeed;
if ((this.x <= 2) || (this.x + size >= (centerX * 2) - 2)) {
xSpeed = -xSpeed;
}
if ((this.y <= 2) || (this.y + size >= (centerY * 2) - 2)) {
ySpeed = -ySpeed;
}
}
}
public void testPlanet(int x, int y) {
if ((x > this.x) && (y > this.y) &&
(x < this.x + size) && (y < this.y + size)) {
this.bounce = true;
xSpeed = Math.random() * 8 + 2;
if (Math.random() > .5) {
xSpeed = -xSpeed;
}
ySpeed = Math.random() * 8 + 2;
if (Math.random() > .5) {
ySpeed = -ySpeed;
}
}
}
public void unBouncePlanet() {
this.bounce = false;
}
public void drawOrbit(Graphics g, int centerX, int centerY) {
g.setColor(Color.white);
g.drawOval(centerX - distance, centerY - distance, distance * 2, distance * 2);
}
public void drawPlanet(Graphics g) {
g.setColor(this.color);
g.fillOval((int)(this.x), (int)(this.y), this.size, this.size);
}
}
class motion extends Thread {
private solarSystemCanvas ssc;
public motion(solarSystemCanvas ssc) {
this.ssc = ssc;
}
public void run() {
while(true) {
ssc.repaint();
try {
sleep(20);
}
catch(InterruptedException ie) {}
}
}
}