So here is the first entry in the learning class!!
Subject : What is your core applet code? The essential part that you have in every applet when you make a game.
Description
The essential parts of my applet are the following elements :
- start() method creating the canvas, the bufferstrategy and the input listeners as well as starting the gameloop.
- a gameloop.
- a couple of input listeners (MouseListener, KeyListener, etc.).
- render(Graphics2D g) method to draw on the canvas.
- update(int deltaTime) method to update the game state.
Code
import java.applet.Applet;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.image.BufferStrategy;
public class BasicApplet extends Applet implements Runnable{
private final int width = 800;
private final int height = 600;
Canvas canvas;
BufferStrategy bufferStrategy;
Thread gameloopThread;
@Override
public void init(){
canvas = new Canvas();
canvas.setBounds(0, 0, width, height);
add(canvas);
canvas.setIgnoreRepaint(true);
canvas.createBufferStrategy(2);
bufferStrategy = canvas.getBufferStrategy();
canvas.addMouseListener(new MouseControl());
canvas.addMouseMotionListener(new MouseControl());
canvas.requestFocus();
}
@Override
public void start(){
gameloopThread = new Thread(this);
gameloopThread.start();
}
@Override
public void stop(){
setRunning(false);
try {
gameloopThread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private class MouseControl extends MouseAdapter{
}
private long desiredFPS = 60;
private long desiredDeltaLoop = (1000*1000*1000)/desiredFPS;
private boolean running = true;
private synchronized void setRunning(boolean running){
this.running = running;
}
private synchronized boolean isRunning(){
return running;
}
public void run(){
setRunning(true);
long beginLoopTime;
long endLoopTime;
long currentUpdateTime = System.nanoTime();
long lastUpdateTime;
long deltaLoop;
while(!isActive()){
Thread.yield();
}
while(isRunning()){
beginLoopTime = System.nanoTime();
render();
lastUpdateTime = currentUpdateTime;
currentUpdateTime = System.nanoTime();
update((int) ((currentUpdateTime - lastUpdateTime)/(1000*1000)));
endLoopTime = System.nanoTime();
deltaLoop = endLoopTime - beginLoopTime;
if(deltaLoop > desiredDeltaLoop){
//Do nothing. We are already late.
}else{
try{
Thread.sleep((desiredDeltaLoop - deltaLoop)/(1000*1000));
}catch(InterruptedException e){
//Do nothing
}
}
}
}
private void render() {
try{
Graphics2D g = (Graphics2D) bufferStrategy.getDrawGraphics();
g.clearRect(0, 0, width, height);
render(g);
bufferStrategy.show();
g.dispose();
}catch(Exception e){
e.printStackTrace();
}
}
/**
* Overwrite this method in subclass
*/
protected void update(int deltaTime){
}
/**
* Overwrite this method in subclass
*/
protected void render(Graphics2D g){
}
}
Notes
[Warning] There might be some tearing with the rendering.
