我正在尝试用下载的applet制作游戏。我改变了一切，直到我没有错误，但当我运行它时，它显示一个空框架，我不知道什么是错的！
a.java：
package game;
import javax.swing.JFrame;
public class a {
public a() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,500);
frame.add(new b());
frame.setVisible(true);
}
public static void main(String [] args) {
a a = new a();
}
}
b.java：
package game;
import java.awt.Color;
import java.awt.Event;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;
public class b extends JPanel implements Runnable {
Thread thread;
static final int TILE_SIZE = 16;
static final int WALL_HEIGHT = 16;
static final int PROJECTIONPLANEWIDTH = 320;
static final int PROJECTIONPLANEHEIGHT = 200;
static final int ANGLE60 = PROJECTIONPLANEWIDTH;
static final int ANGLE30 = (ANGLE60 / 2);
static final int ANGLE15 = (ANGLE30 / 2);
static final int ANGLE90 = (ANGLE30 * 3);
static final int ANGLE180 = (ANGLE90 * 2);
static final int ANGLE270 = (ANGLE90 * 3);
static final int ANGLE360 = (ANGLE60 * 6);
static final int ANGLE0 = 0;
static final int ANGLE5 = (ANGLE30 / 6);
static final int ANGLE10 = (ANGLE5 * 2);
float fSinTable[];
float fISinTable[];
float fCosTable[];
float fICosTable[];
float fTanTable[];
float fITanTable[];
float fFishTable[];
float fXStepTable[];
float fYStepTable[];
Image fOffscreenImage;
Graphics fOffscreenGraphics;
int fPlayerX = 100;
int fPlayerY = 160;
int fPlayerArc = ANGLE0;
int fPlayerDistanceToTheProjectionPlane = 277;
int fPlayerHeight = 32;
int fPlayerSpeed = 8;
int fProjectionPlaneYCenter = PROJECTIONPLANEHEIGHT / 2;
boolean fKeyUp = false;
boolean fKeyDown = false;
boolean fKeyLeft = false;
boolean fKeyRight = false;
byte fMap[];
static final byte W = 1; // wall
static final byte O = 0; // opening
static final int MAP_WIDTH = 12;
static final int MAP_HEIGHT = 12;
private boolean run = true;
float arcToRad(float arcAngle) {
return ((float) (arcAngle * Math.PI) / (float) ANGLE180);
}
public void createTables() {
int i;
float radian;
fSinTable = new float[ANGLE360 + 1];
fISinTable = new float[ANGLE360 + 1];
fCosTable = new float[ANGLE360 + 1];
fICosTable = new float[ANGLE360 + 1];
fTanTable = new float[ANGLE360 + 1];
fITanTable = new float[ANGLE360 + 1];
fFishTable = new float[ANGLE60 + 1];
fXStepTable = new float[ANGLE360 + 1];
fYStepTable = new float[ANGLE360 + 1];
for (i = 0; i <= ANGLE360; i++) {
radian = arcToRad(i) + (float) (0.0001);
fSinTable[i] = (float) Math.sin(radian);
fISinTable[i] = (1.0F / (fSinTable[i]));
fCosTable[i] = (float) Math.cos(radian);
fICosTable[i] = (1.0F / (fCosTable[i]));
fTanTable[i] = (float) Math.tan(radian);
fITanTable[i] = (1.0F / fTanTable[i]);
if (i >= ANGLE90 && i < ANGLE270) {
fXStepTable[i] = (float) (TILE_SIZE / fTanTable[i]);
if (fXStepTable[i] > 0) {
fXStepTable[i] = -fXStepTable[i];
}
} else {
fXStepTable[i] = (float) (TILE_SIZE / fTanTable[i]);
if (fXStepTable[i] < 0) {
fXStepTable[i] = -fXStepTable[i];
}
}
if (i >= ANGLE0 && i < ANGLE180) {
fYStepTable[i] = (float) (TILE_SIZE * fTanTable[i]);
if (fYStepTable[i] < 0) {
fYStepTable[i] = -fYStepTable[i];
}
} else {
fYStepTable[i] = (float) (TILE_SIZE * fTanTable[i]);
if (fYStepTable[i] > 0) {
fYStepTable[i] = -fYStepTable[i];
}
}
}
for (i = -ANGLE30; i <= ANGLE30; i++) {
radian = arcToRad(i);
fFishTable[i + ANGLE30] = (float) (1.0F / Math.cos(radian));
}
byte[] map = {
W, W, W, W, W, W, W, W, W, W, W, W,
W, O, O, O, O, O, O, O, O, O, O, W,
W, O, O, O, O, O, O, O, O, O, O, W,
W, O, O, O, O, O, O, O, W, O, O, W,
W, O, O, W, O, W, O, O, W, O, O, W,
W, O, O, W, O, W, W, O, W, O, O, W,
W, O, O, W, O, O, W, O, W, O, O, W,
W, O, O, O, W, O, W, O, W, O, O, W,
W, O, O, O, W, O, W, O, W, O, O, W,
W, O, O, O, W, W, W, O, W, O, O, W,
W, O, O, O, O, O, O, O, O, O, O, W,
W, W, W, W, W, W, W, W, W, W, W, W
};
fMap = map;
}
public void start() {
createTables();
thread = new Thread(this);
thread.start();
}
public void run() {
start();
fOffscreenImage = createImage(size().width, size().height);
fOffscreenGraphics = fOffscreenImage.getGraphics();
while (true) {
if (fKeyLeft) {
if ((fPlayerArc -= ANGLE10) < ANGLE0) {
fPlayerArc += ANGLE360;
}
} else if (fKeyRight) {
if ((fPlayerArc += ANGLE10) >= ANGLE360) {
fPlayerArc -= ANGLE360;
}
}
float playerXDir = fCosTable[fPlayerArc];
float playerYDir = fSinTable[fPlayerArc];
if (fKeyUp) {
fPlayerX += (int) (playerXDir * fPlayerSpeed);
fPlayerY += (int) (playerYDir * fPlayerSpeed);
} else if (fKeyDown) {
fPlayerX -= (int) (playerXDir * fPlayerSpeed);
fPlayerY -= (int) (playerYDir * fPlayerSpeed);
}
render();
try {
Thread.sleep(50);
} catch (Exception sleepProblem) {
System.out.println("Sleep problem");
}
}
}
public void drawBackground() {
int c = 25;
int r;
for (r = 0; r < PROJECTIONPLANEHEIGHT / 2; r += 10) {
fOffscreenGraphics.setColor(new Color(c, 125, 225));
fOffscreenGraphics.fillRect(0, r, PROJECTIONPLANEWIDTH, 10);
c += 20;
}
c = 22;
for (; r < PROJECTIONPLANEHEIGHT; r += 15) {
fOffscreenGraphics.setColor(new Color(c, 20, 20));
fOffscreenGraphics.fillRect(0, r, PROJECTIONPLANEWIDTH, 15);
c += 15;
}
}
public void render() {
drawBackground();
int verticalGrid;
int horizontalGrid;
int distToNextVerticalGrid;
int distToNextHorizontalGrid;
float xIntersection;
float yIntersection;
float distToNextXIntersection;
float distToNextYIntersection;
int xGridIndex;
int yGridIndex;
float distToVerticalGridBeingHit;
float distToHorizontalGridBeingHit;
int castArc, castColumn;
castArc = fPlayerArc;
castArc -= ANGLE30;
if (castArc < 0) {
castArc = ANGLE360 + castArc;
}
for (castColumn = 0; castColumn < PROJECTIONPLANEWIDTH; castColumn += 5) {
if (castArc > ANGLE0 && castArc < ANGLE180) {
horizontalGrid = (fPlayerY / TILE_SIZE) * TILE_SIZE + TILE_SIZE;
distToNextHorizontalGrid = TILE_SIZE;
float xtemp = fITanTable[castArc] * (horizontalGrid - fPlayerY);
xIntersection = xtemp + fPlayerX;
} else {
horizontalGrid = (fPlayerY / TILE_SIZE) * TILE_SIZE;
distToNextHorizontalGrid = -TILE_SIZE;
float xtemp = fITanTable[castArc] * (horizontalGrid - fPlayerY);
xIntersection = xtemp + fPlayerX;
horizontalGrid--;
}
if (castArc == ANGLE0 || castArc == ANGLE180) {
distToHorizontalGridBeingHit = 9999999F;
} else {
distToNextXIntersection = fXStepTable[castArc];
while (true) {
xGridIndex = (int) (xIntersection / TILE_SIZE);
yGridIndex = (horizontalGrid / TILE_SIZE);
if ((xGridIndex >= MAP_WIDTH)
|| (yGridIndex >= MAP_HEIGHT)
|| xGridIndex < 0 || yGridIndex < 0) {
distToHorizontalGridBeingHit = Float.MAX_VALUE;
break;
} else if ((fMap[yGridIndex * MAP_WIDTH + xGridIndex]) != O) {
distToHorizontalGridBeingHit = (xIntersection - fPlayerX) * fICosTable[castArc];
break;
}
else {
xIntersection += distToNextXIntersection;
horizontalGrid += distToNextHorizontalGrid;
}
}
}
if (castArc < ANGLE90 || castArc > ANGLE270) {
verticalGrid = TILE_SIZE + (fPlayerX / TILE_SIZE) * TILE_SIZE;
distToNextVerticalGrid = TILE_SIZE;
float ytemp = fTanTable[castArc] * (verticalGrid - fPlayerX);
yIntersection = ytemp + fPlayerY;
}
else {
verticalGrid = (fPlayerX / TILE_SIZE) * TILE_SIZE;
distToNextVerticalGrid = -TILE_SIZE;
float ytemp = fTanTable[castArc] * (verticalGrid - fPlayerX);
yIntersection = ytemp + fPlayerY;
verticalGrid--;
}
if (castArc == ANGLE90 || castArc == ANGLE270) {
distToVerticalGridBeingHit = 9999999;
} else {
distToNextYIntersection = fYStepTable[castArc];
while (true) {
xGridIndex = (verticalGrid / TILE_SIZE);
yGridIndex = (int) (yIntersection / TILE_SIZE);
if ((xGridIndex >= MAP_WIDTH)
|| (yGridIndex >= MAP_HEIGHT)
|| xGridIndex < 0 || yGridIndex < 0) {
distToVerticalGridBeingHit = Float.MAX_VALUE;
break;
} else if ((fMap[yGridIndex * MAP_WIDTH + xGridIndex]) != O) {
distToVerticalGridBeingHit = (yIntersection - fPlayerY) * fISinTable[castArc];
break;
} else {
yIntersection += distToNextYIntersection;
verticalGrid += distToNextVerticalGrid;
}
}
}
float scaleFactor;
float dist;
int topOfWall;
int bottomOfWall;
if (distToHorizontalGridBeingHit < distToVerticalGridBeingHit) {
dist = distToHorizontalGridBeingHit;
fOffscreenGraphics.setColor(Color.gray);
} else {
dist = distToVerticalGridBeingHit;
fOffscreenGraphics.setColor(Color.darkGray);
}
dist /= fFishTable[castColumn];
int projectedWallHeight = (int) (WALL_HEIGHT * (float) fPlayerDistanceToTheProjectionPlane / dist);
bottomOfWall = fProjectionPlaneYCenter + (int) (projectedWallHeight * 0.5F);
topOfWall = PROJECTIONPLANEHEIGHT - bottomOfWall;
if (bottomOfWall >= PROJECTIONPLANEHEIGHT) {
bottomOfWall = PROJECTIONPLANEHEIGHT - 1;
}
fOffscreenGraphics.fillRect(castColumn, topOfWall, 5, projectedWallHeight);
castArc += 5;
if (castArc >= ANGLE360) {
castArc -= ANGLE360;
}
}
paint(getGraphics());
}
public void paint(Graphics g) {
if (fOffscreenImage!=null) g.drawImage(fOffscreenImage, 0, 0, this);
}
public boolean keyDown(Event evt, int key)
{
switch (key)
{
case Event.ESCAPE:
System.exit(0);
case Event.UP:
fKeyUp=true;
break;
case Event.DOWN:
fKeyDown=true;
break;
case Event.LEFT:
fKeyLeft=true;
break;
case Event.RIGHT:
fKeyRight=true;
break;
default:
}
return true;
}
public boolean keyUp(Event evt, int key)
{
switch (key)
{
case Event.UP:
fKeyUp=false;
break;
case Event.DOWN:
fKeyDown=false;
break;
case Event.LEFT:
fKeyLeft=false;
break;
case Event.RIGHT:
fKeyRight=false;
break;
default:
}
return true;
}
}
答案 0 :(得分：3)
我没有查看所有代码，但是您发布的课程中存在一些基本缺陷：
b的新实例与创建空JPanel相同。当然，面板是空的，你什么都看不见。首先填充面板，然后添加它。Thread填充b面板违反了Swing线程规则。您应该只访问/修改/ ...在事件调度线程上摆动组件。有关详细信息，请参阅Swing concurrency guide Thread.sleep会阻止您的用户界面。从来没有这样做过。如果您想要某种动画，请改用javax.swing.Timer类。此类旨在定期更新您的UI。paint方法，而应覆盖paintComponent方法，并且不要忘记致电super