如果我有代码：
private final FPS = 30;
private final SIZE = 10;
private int x = 10;
private int y = 0;
private String myFps;
private void start(){
while(true){
moveRect();
paint();
}
}
private void paint(){
g2.drawRect(x, y, SIZE, SIZE);
g2.drawString(myFps, 10, 10);
}
private void moveRect(){
x++;
}
答案 0 :(得分：1)
这是我非常古老的简单Java Graphics + BufferStrategy gameloop测试应用程序的copypaste。动画循环绘制很少的移动矩形和fps计数器。
java -cp ./lib/test.jar GameLoop2“fullscreen = false”“fps = 60” “VSYNC =真”
//http://www.javagaming.org/index.php/topic,19971.0.html
//http://fivedots.coe.psu.ac.th/~ad/jg/ch1/ch1.pdf
import java.util.*;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferStrategy;
import java.awt.DisplayMode; // for full-screen mode
public class GameLoop2 implements KeyListener {
Frame mainFrame;
private static final long NANO_IN_MILLI = 1000000L;
// num of iterations with a sleep delay of 0ms before
// game loop yields to other threads.
private static final int NO_DELAYS_PER_YIELD = 16;
// max num of renderings that can be skipped in one game loop,
// game's internal state is updated but not rendered on screen.
private static int MAX_RENDER_SKIPS = 5;
private static int TARGET_FPS = 60;
//private long prevStatsTime;
private long gameStartTime;
private long curRenderTime;
private long rendersSkipped = 0L;
private long period; // period between rendering in nanosecs
long fps;
long frameCounter;
long lastFpsTime;
Rectangle2D rect, rect2, rect3;
/**
* Create a new GameLoop that will use the specified GraphicsDevice.
*
* @param device
*/
public GameLoop2(Map<String,String> args, GraphicsDevice device) {
try {
if (args.containsKey("fps"))
TARGET_FPS = Integer.parseInt(args.get("fps"));
// Setup the frame
GraphicsConfiguration gc = device.getDefaultConfiguration();
mainFrame = new Frame(gc);
//mainFrame.setUndecorated(true);
mainFrame.setIgnoreRepaint(true);
mainFrame.setVisible(true);
mainFrame.setSize(640, 480);
//mainFrame.setLocationRelativeTo();
mainFrame.setLocation(700,100);
mainFrame.createBufferStrategy(2);
mainFrame.addKeyListener(this);
if ("true".equalsIgnoreCase(args.get("fullscreen"))) {
device.setFullScreenWindow(mainFrame);
device.setDisplayMode(new DisplayMode(640, 480, 8, DisplayMode.REFRESH_RATE_UNKNOWN));
}
final boolean VSYNC = "true".equalsIgnoreCase(args.get("vsync"));
// Cache the buffer strategy and create a rectangle to move
BufferStrategy bufferStrategy = mainFrame.getBufferStrategy();
rect = new Rectangle2D.Float(0,100, 64,64);
rect2 = new Rectangle2D.Float(0,200, 32,32);
rect3 = new Rectangle2D.Float(500,300, 128,128);
// loop initialization
long beforeTime, afterTime, timeDiff, sleepTime;
long overSleepTime = 0L;
int noDelays = 0;
long excess = 0L;
gameStartTime = System.nanoTime();
//prevStatsTime = gameStartTime;
beforeTime = gameStartTime;
period = (1000L*NANO_IN_MILLI)/TARGET_FPS; // rendering FPS (nanosecs/targetFPS)
System.out.println("FPS: " + TARGET_FPS + ", vsync=" + VSYNC);
System.out.println("FPS period: " + period);
// Main loop
while(true) {
// **2) execute physics
updateWorld(0);
// **1) execute drawing
Graphics g = bufferStrategy.getDrawGraphics();
drawScreen(g);
g.dispose();
// Synchronise with the display hardware. Note that on
// Windows Vista this method may cause your screen to flash.
// If that bothers you, just comment it out.
if (VSYNC) Toolkit.getDefaultToolkit().sync();
// Flip the buffer
if( !bufferStrategy.contentsLost() )
bufferStrategy.show();
afterTime = System.nanoTime();
curRenderTime = afterTime;
calculateFramesPerSecond();
timeDiff = afterTime - beforeTime;
sleepTime = (period-timeDiff) - overSleepTime;
if (sleepTime > 0) { // time left in cycle
//System.out.println("sleepTime: " + (sleepTime/NANO_IN_MILLI));
try {
Thread.sleep(sleepTime/NANO_IN_MILLI);//nano->ms
} catch(InterruptedException ex){}
overSleepTime = (System.nanoTime()-afterTime) - sleepTime;
} else { // sleepTime <= 0;
System.out.println("Rendering too slow");
// this cycle took longer than period
excess -= sleepTime;
// store excess time value
overSleepTime = 0L;
if (++noDelays >= NO_DELAYS_PER_YIELD) {
Thread.yield();
// give another thread a chance to run
noDelays = 0;
}
}
beforeTime = System.nanoTime();
/* If the rendering is taking too long, then
update the game state without rendering
it, to get the UPS nearer to the
required frame rate. */
int skips = 0;
while((excess > period) && (skips < MAX_RENDER_SKIPS)) {
// update state but don’t render
System.out.println("Skip renderFPS, run updateFPS");
excess -= period;
updateWorld(0);
skips++;
}
rendersSkipped += skips;
}
} catch (Exception ex) {
ex.printStackTrace();
} finally {
device.setFullScreenWindow(null);
}
}
private void updateWorld(long elapsedTime) {
// speed: 150 pixels per second
//double xMov = (140f/(NANO_IN_MILLI*1000)) * elapsedTime;
double posX = rect.getX() + (140f / TARGET_FPS);
if (posX > mainFrame.getWidth())
posX = -rect.getWidth();
rect.setRect(posX, rect.getY(), rect.getWidth(), rect.getHeight());
posX = rect2.getX() + (190f / TARGET_FPS);
if (posX > mainFrame.getWidth())
posX = -rect2.getWidth();
rect2.setRect(posX, rect2.getY(), rect2.getWidth(), rect2.getHeight());
posX = rect3.getX() - (300f / TARGET_FPS);
if (posX < -rect3.getWidth())
posX = mainFrame.getWidth();
rect3.setRect(posX, rect3.getY(), rect3.getWidth(), rect3.getHeight());
}
private void drawScreen(Graphics g) {
g.setColor(Color.BLACK);
g.fillRect(0, 0, mainFrame.getWidth(), mainFrame.getHeight());
g.setColor(Color.WHITE);
g.drawString("FPS: " + fps, 40, 50);
g.setColor(Color.RED);
g.fillRect((int)rect.getX(), (int)rect.getY(), (int)rect.getWidth(), (int)rect.getHeight());
g.setColor(Color.GREEN);
g.fillRect((int)rect2.getX(), (int)rect2.getY(), (int)rect2.getWidth(), (int)rect2.getHeight());
g.setColor(Color.BLUE);
g.fillRect((int)rect3.getX(), (int)rect3.getY(), (int)rect3.getWidth(), (int)rect3.getHeight());
}
private void calculateFramesPerSecond() {
if( curRenderTime - lastFpsTime >= NANO_IN_MILLI*1000 ) {
fps = frameCounter;
frameCounter = 0;
lastFpsTime = curRenderTime;
}
frameCounter++;
}
public void keyPressed(KeyEvent e) {
if( e.getKeyCode() == KeyEvent.VK_ESCAPE ) {
System.exit(0);
}
}
public void keyReleased(KeyEvent e) { }
public void keyTyped(KeyEvent e) { }
public static void main(String[] args) {
try {
Map<String,String> mapArgs = parseArguments(args);
GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice device = env.getDefaultScreenDevice();
new GameLoop2(mapArgs, device);
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* Parse commandline arguments, each parameter is a name-value pair.
* Example: java.exe MyApp "key1=value1" "key2=value2"
*/
private static Map<String,String> parseArguments(String[] args) {
Map<String,String> mapArgs = new HashMap<String,String>();
for(int idx=0; idx < args.length; idx++) {
String val = args[idx];
int delimIdx = val.indexOf('=');
if (delimIdx < 0) {
mapArgs.put(val, null);
} else if (delimIdx == 0) {
mapArgs.put("", val.substring(1));
} else {
mapArgs.put(
val.substring(0, delimIdx).trim(),
val.substring(delimIdx+1)
);
}
}
return mapArgs;
}
}