子弹的发射
Posted B_Lasting_尊
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实现思路：
1、获取tank的宽高
2、根据tank的方向更换子弹的图片
3、获取每个方向子弹图片的宽高
4、计算出子弹的坐标
5、为子弹加速
代码实现：
1、定义Element类，属性有坐标、宽高和图片路径，方法有draw()方法和getSize()方法
1 package Itheima.bean;
2
3 import java.io.IOException;
4
5 import org.itheima.game.utils.DrawUtils;
6
7 public class Element {
8 int x; //x坐标
9 int y; //y坐标
10 int width; //宽度
11 int height; //高度
12 String imagePath; //图片路径
13 public void draw() {
14 try {
15 DrawUtils.draw(imagePath, x, y);
16 } catch (IOException e) {
17 // TODO 自动生成的 catch 块
18 e.printStackTrace();
19 }
20 }
21 public void getSize(){ //获取图片宽高
22 try {
23 int[] size = DrawUtils.getSize(imagePath);
24 this.width=size[0];
25 this.height=size[1];
26 } catch (IOException e) {
27 // TODO 自动生成的 catch 块
28 e.printStackTrace();
29 }
30 }
31 }
2、让Tank类和Bullet类继承Element类
1 package Itheima;
2
3 import java.util.List;
4 import java.util.concurrent.CopyOnWriteArrayList;
5
6 import org.itheima.game.Window;
7 import org.lwjgl.input.Keyboard;
8
9 import Itheima.bean.Bullet;
10 import Itheima.bean.Direction;
11 import Itheima.bean.Element;
12 import Itheima.bean.Tank;
13
14 public class TankWorld extends Window {
15 Tank tank;
16 List<Element> list;
17
18 public TankWorld(String title, int width, int height, int fps) {
19 super(title, width, height, fps);
20 // TODO 自动生成的构造函数存根
21 }
22
23 @Override
24 protected void onCreate() {
25 list = new CopyOnWriteArrayList<>();
26 tank = new Tank(0, 0);
27 list.add(tank);
28 }
29
30 @Override
31 protected void onMouseEvent(int key, int x, int y) {
32 // TODO 自动生成的方法存根
33
34 }
35
36 @Override
37 protected void onKeyEvent(int key) {
38 switch (key) {
39 case Keyboard.KEY_UP:
40 tank.move(Direction.UP);
41 break;
42
43 case Keyboard.KEY_DOWN:
44 tank.move(Direction.DOWN);
45 break;
46 case Keyboard.KEY_LEFT:
47 tank.move(Direction.LEFT);
48 break;
49 case Keyboard.KEY_RIGHT:
50 tank.move(Direction.RIGHT);
51 break;
52 case Keyboard.KEY_SPACE:
53 Bullet bullet = tank.fire();
54 list.add(bullet);
55 break;
56 }
57 }
58
59 @Override
60 protected void onDisplayUpdate() {
61 for (Element e : list) {
62 e.draw();
63 }
64 }
65
66 }
1 package Itheima.bean;
2
3 import Itheima.Constants;
4
5 public class Tank extends Element {
6 private int speed = 32; //移动速度
7 Direction dir = Direction.UP; //方向默认向上
8 public Tank(int x, int y) { //构造方法
9 this.x = x;
10 this.y = y;
11 this.imagePath = "res/img/tank_u.gif";
12 getSize(); //获取tank宽高
13 }
14
15 public void move(Direction dir) {
16 if(dir!=this.dir){ //传入的方向不等于当前方向
17 this.dir=dir; //当前方向等于传入的方向
18 switch (dir) { //只更换方向不做移动
19 case UP:
20 this.imagePath = "res/img/tank_u.gif";
21 break;
22
23 case DOWN:
24 this.imagePath = "res/img/tank_d.gif";
25 break;
26 case LEFT:
27 this.imagePath = "res/img/tank_l.gif";
28 break;
29 case RIGHT:
30 this.imagePath = "res/img/tank_r.gif";
31 break;
32 }
33 }
34 switch (dir) { //如果当前方向等于传入的方向
35 case UP:
36 y -= speed;
37 break;
38
39 case DOWN:
40 y += speed;
41 break;
42 case LEFT:
43 x -= speed;
44 break;
45 case RIGHT:
46 x += speed;
47 break;
48 }
49 //越界处理
50 if(x<0){
51 x=0;
52 }
53 if(x>Constants.WIDTH-this.width){
54 x=Constants.WIDTH-this.width;
55 }
56 if(y<0){
57 y=0;
58 }
59 if(y>Constants.HEIGHT-this.height){
60 y=Constants.HEIGHT-this.height;
61 }
62 }
63
64 public Bullet fire() {
65 Bullet b = new Bullet(this); //根据tank坐标生成子弹
66 return b;
67 }
68 }
1 package Itheima.bean;
2
3 import java.io.IOException;
4
5 import org.itheima.game.utils.DrawUtils;
6
7 public class Bullet extends Element {
8 Direction dir;
9 private int speed = 32; //子弹速度
10 public Bullet(Tank tank) {
11 int x1 = tank.x;
12 int y1 = tank.y;
13 int w1 = tank.width;
14 int h1 = tank.height;
15 this.dir = tank.dir;
16 switch (dir) { //根据tank的方向计算子弹坐标
17 case UP:
18 this.imagePath = "res/img/bullet_u.gif";
19 getSize();
20 this.x = x1 + (w1 - this.width) / 2;
21 this.y = y1 - this.height;
22 break;
23
24 case DOWN:
25 this.imagePath = "res/img/bullet_d.gif";
26 getSize();
27 this.x = x1 + (w1 - this.width) / 2;
28 this.y = y1 + w1;
29 break;
30 case LEFT:
31 this.imagePath = "res/img/bullet_l.gif";
32 getSize();
33 this.x = x1 - this.width;
34 this.y = y1 + (h1 - this.height) / 2;
35 break;
36 case RIGHT:
37 this.imagePath = "res/img/bullet_r.gif";
38 getSize();
39 this.x = x1 + w1;
40 this.y = y1 + (h1 - this.height) / 2;
41 break;
42 }
43 }
44
45 public void draw() { //重写draw方法
46 try {
47 DrawUtils.draw(imagePath, x, y);
48 } catch (IOException e) {
49 // TODO 自动生成的 catch 块
50 e.printStackTrace();
51 }
52 switch (dir) {
53 case UP:
54 y -= speed;
55 break;
56
57 case DOWN:
58 y += speed;
59 break;
60 case LEFT:
61 x -= speed;
62 break;
63 case RIGHT:
64 x += speed;
65 break;
66 }
67 }
68 }
随笔说：
本节实现了子弹对象的创建、坐标的计算、移动效果。体会到继承的好处，
以及游戏实现原理。
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