我刚刚开始尝试制作游戏，我做了一个HelloWorld Applet，然后测试了我的想法滚动它，最终它开始变成一个“直升机”风格的游戏。现在一切正常，直到我决定放入一堆switch语句来处理状态（标题屏幕，运行和游戏结束）。以前运行的代码没有改变，我的新“介绍屏幕”工作正常，但是当你切换到游戏状态时，双缓冲似乎没有出现问题。游戏前景快速闪烁，并从中切出三角形，背景几乎无法渲染。这只是我探索游戏编码的基本原则，所以它不优雅或模块化或任何东西，但它应该工作......
[编辑]我知道Applets和AWT一般来说可能是一个糟糕的方式，但我这样开始，我只是想了解它是如何工作的以及我做错了所以我可以满意继续前进。
package testStuff;
import java.awt.*;
import java.applet.*;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class HelloWorld extends Applet implements Runnable{
//game time counter
int count = 0;
//controller object
Controller control;
//accesses images and creates image variables
File wavesource = new File("C:\\sourceimages\\waves.jpg");
File playerSource = new File("C:\\sourceimages\\plane3.png");
Image player = null;
Image waves = null;
//font for score
Font myFont;
//double buffer objects
Graphics bground;
Image bgImage = null;
private int bgx = 0;
//player position
private int xPos=0;
private int yPos=50;
//arrays for tunnel locations
private int[] topTunnel = new int[200];
private int[] botTunnel = new int[200];
//size of tunnel
private int tunnelSize;
//boolean determines direction of tunnel movement
private boolean tunUp;
//state
private int state;
//"constructor"
public void init(){
//set state
state = 0;
//instantiates controller adds it to the applet
control = new Controller();
this.addKeyListener(control);
//instantiates images
try {
waves = ImageIO.read(wavesource);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
player = ImageIO.read(playerSource);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//instantiates arrays and tunnel size
for(int i=0;i<199;i++){
topTunnel[i]=-1;
botTunnel[i]=-1;
}
topTunnel[199]=20;
botTunnel[199]=179;
tunnelSize = botTunnel[199]-topTunnel[199];
tunUp = false;
}
public void paint(Graphics g){
switch(state){
case 0:
g.setColor(Color.black);
myFont = new Font("Courier", Font.BOLD+Font.ITALIC, 12);
g.setFont(myFont);
g.drawString("DON'T CRASH THE PLANE BRO", 10, 100);
myFont = new Font("Courier", Font.PLAIN, 8);
g.setFont(myFont);
g.drawString("Press Spacebar to Play", 40, 150);
break;
case 1:
g.drawImage(player, xPos, yPos, null);
g.setColor(Color.red);
for(int i=0;i<200;i++){
g.fillRect(i, 0, 1, topTunnel[i]);
g.fillRect(i, botTunnel[i], 1, botTunnel[i]);
}
g.setColor(Color.cyan);
myFont = new Font("Helvetica", Font.PLAIN, 12);
setFont(myFont);
if(count<170)
g.drawString("SCORE: " + 0, 0, 12);
else
g.drawString("SCORE: " + (this.count-170), 0, 12);
break;
}
}
public void start(){
Thread thread = new Thread(this);
thread.start();
}
@Override
public void run(){
while(true){
switch(state){
case 0:
//increases count
count++;
//paints
this.repaint();
try {
Thread.sleep(1000/30);
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
if(control.spaceDown()){
state = 1;
count = 0;
}
break;
case 1:
//increases count
count++;
//handles scrolling
if(xPos<75){
xPos++;
}
else{
if(bgx>-600){
bgx--;
}
else{
bgx=0;
}
}
//handles input
if(control.spaceDown()==true&&yPos>=0){
yPos--;
}
else if(yPos<180){
yPos++;
}
//repositions tunnel
if(xPos>=75){
for(int i=1;i<200;i++){
topTunnel[i-1]=topTunnel[i];
botTunnel[i-1]=botTunnel[i];
}
}
//defines new tunnel space
if(topTunnel[199]<=0 || !tunUp)
topTunnel[199]++;
if(botTunnel[199]>=200 || tunUp)
topTunnel[199]--;
botTunnel[199] = topTunnel[199]+tunnelSize;
//randomly chooses direction to move tunnel
double randomNum = Math.random();
if(randomNum>.5)
tunUp = true;
else
tunUp = false;
//narrows tunnel
if(count%20 == 0)
tunnelSize--;
//calls update
this.repaint();
//handles framerate
try {
Thread.sleep(1000/30);
} catch (InterruptedException e) {
//TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
}
}
public void update(Graphics g){
//instantiates image and graphics on first tick
if(bgImage == null){
bgImage = createImage(this.getSize().width, this.getSize().height);
bground = bgImage.getGraphics();
}
//create background based on state
switch(state){
case 0:
//flashing colors!
if(count%20<10){
bground.setColor(Color.yellow);
bground.fillRect(0, 0, 200, 200);
}
else{
bground.setColor(Color.orange);
bground.fillRect(0, 0, 200, 200);
}
break;
case 1:
//draws background image(s)
bground.drawImage(waves,bgx,0,this);
if(bgx<-399)
bground.drawImage(waves,bgx+600,0,this);
break;
}
//paint over the background then draw it to screen
paint(bground);
g.drawImage(bgImage, 0, 0, this);
}
}
答案 0 :(得分：1)
您需要“清除”每个画面上的图形，否则您正在绘制之前绘制的图像......
在下面的示例中，我在“播放”时填充了图形上下文，但是当它暂停时保持原样，您应该能够看到差异......
public class HelloWorld extends Applet implements Runnable {
private int direction = 4;
private int state = 0;
private Image bgImage;
private Graphics bground;
private int count;
private int x = 0;
//"constructor"
public void init() {
addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_SPACE) {
if (state == 0) {
state = 1;
} else if (state == 1) {
state = 0;
}
}
}
});
}
public void paint(Graphics g) {
switch (state) {
case 0:
g.setColor(Color.black);
g.drawString("DON'T CRASH THE PLANE BRO", 10, 100);
g.drawString("Press Spacebar to Play", 40, 150);
break;
case 1:
break;
}
}
public void start() {
Thread thread = new Thread(this);
thread.start();
}
@Override
public void run() {
while (true) {
switch (state) {
case 0:
count++;
this.repaint();
break;
case 1:
x += direction;
if (x < 0) {
x = 0;
direction *= -1;
} else if (x > getWidth()) {
x = getWidth();
direction *= -1;
}
//calls update
this.repaint();
//handles framerate
try {
Thread.sleep(1000 / 30);
} catch (InterruptedException e) {
//TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
}
}
public void update(Graphics g) {
//instantiates image and graphics on first tick
if (bgImage == null) {
bgImage = createImage(this.getSize().width, this.getSize().height);
bground = bgImage.getGraphics();
}
//create background based on state
switch (state) {
case 0:
//flashing colors!
if (count % 20 < 10) {
bground.setColor(Color.yellow);
bground.fillRect(0, 0, 200, 200);
} else {
bground.setColor(Color.orange);
bground.fillRect(0, 0, 200, 200);
}
break;
case 1:
bground.setColor(Color.WHITE);
bground.fillRect(0, 0, getWidth(), getHeight());
bground.setColor(Color.RED);
int y = (getHeight() / 2) - 4;
bground.fillOval(x, y, 8, 8);
break;
}
//paint over the background then draw it to screen
paint(bground);
g.drawImage(bgImage, 0, 0, this);
}
}
答案 1 :(得分：0)
我认为你应该开始但是添加更多大括号。我是编码的初学者，但是从我一直在阅读的内容来看，在代码中的某些语句上编写冗长的语句而没有大括号会导致一些错误。
这里有很多流程，我觉得大括号有帮助
//defines new tunnel space if(topTunnel[199]<=0 || !tunUp) topTunnel[199]++; if(botTunnel[199]>=200 || tunUp) topTunnel[199]--; botTunnel[199] = topTunnel[199]+tunnelSize;
//randomly chooses direction to move tunnel
double randomNum = Math.random();
if(randomNum>.5)
tunUp = true;
else
tunUp = false;
//narrows tunnel
if(count%20 == 0)
tunnelSize--;
//calls update
this.repaint();
如果我错了，请纠正我，我也想学习！