Java游戏-如何阻止玩家越过障碍物

Question

我制作了一个非常简单的 2D Java 游戏类，由一般的 2D 游戏方法(如渲染和更新)组成，我设置了所有 if 语句，以便玩家使用键盘箭头输入在 map 上移动。我现在正在尝试设置我读过的是碰撞检测，我知道我需要做什么的基础知识，因为在我真正来这里问问题之前我做了很多阅读，从我读过的内容来看像这样:

制作2个矩形

Rectangle rectOne = new Rectangle(playerX, playerY, 40, 40); 
//keep in mind that the variables playerX and playerY are already made previously
Rectangle rectTwo = new Rectangle(50, 50, 100,100);

然后在我的更新方法下我会说:

if(rectOne.intersects(rectTwo)){//change the player direction so that he 
can go no further}

我只是不明白我的 if 语句中会包含什么，我需要一些东西来阻止我的玩家在交叉点发生时继续前进，但我该如何写这个，因为玩家可以在 4 个不同的方向(向上，向下)移动， 左右)。如果它只是一维的，它会简单得多，因为我可以将方向更改为与原来相反的方向，但它是二维的，所以有点困惑。

附加信息:

我玩游戏的 View 类似于以下内容: http://www.2dplay.com/awesome-tanks/awesome-tanks-play.htm

编辑 3:

                package javagame;

                import java.awt.Rectangle;

                IMPORTS ARE HERE


public class Play extends BasicGameState{

    Animation bucky, movingUp, movingDown, movingLeft, movingRight;
    Image worldMap;
    boolean quit = false;//gives user to quit the game
    int[] duration = {200, 200};//how long frame stays up for
    int buckyPositionX = 0;
    int buckyPositionY = 0;
    int x = buckyPositionX + 320;//keeps user in the middle of the screem
    int y = buckyPositionY + 160;//the numbers are half of the screen size

    Rectangle rectOne = new Rectangle(x, y,90,90);
    Rectangle rectTwo = new Rectangle(500 + buckyPositionX, 330 + buckyPositionY, 210, 150);



private int xSpeed, ySpeed;///////////////////////////CODE FOR COLLISION


    public Play(int state){
    }   
    public void init(GameContainer gc, StateBasedGame sbg) throws SlickException{
          worldMap = new Image("res/world.png");
          Image[] walkUp = {new Image("res/b.png"), new Image("res/b.png")}; //these are the images to be used in the "walkUp" animation
          Image[] walkDown = {new Image("res/f.png"), new Image("res/f.png")};
          Image[] walkLeft = {new Image("res/l.png"), new Image("res/l.png")};
          Image[] walkRight = {new Image("res/r.png"), new Image("res/r.png")};


    movingUp = new Animation(walkUp, duration, false);
    movingDown = new Animation(walkDown, duration, false);  
    movingLeft = new Animation(walkLeft, duration, false);  
    movingRight = new Animation(walkRight, duration, false);

    bucky = movingDown;//facing screen initially on startup
    }


    public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException{
    worldMap.draw(buckyPositionX, buckyPositionY);//position 0,0
    bucky.draw(x, y);//makes him appear at center of map
    g.fillRect(x, y,90,90);
    g.fillRect(500 + buckyPositionX, 330 + buckyPositionY, 210, 150);


    if(quit==true){
        g.drawString("Resume(R)", 250, 100);
        g.drawString("Main(M)", 250, 150);
        g.drawString("Quit Game(Q)", 250, 200);      
        if(quit==false){
            g.clear();//wipe off everything from screen
        }
    }
    }

public void setSpeedWithDirection(int speed, int direction)////////////CODE FOR COLLISION
{
xSpeed = (int) (Math.cos(direction) * speed);//////////////////////////CODE FOR COLLISION
ySpeed = (int) (Math.sin(direction) * speed);//////////////////////////CODE FOR COLLISION
}

    public void update(GameContainer gc, StateBasedGame sbg, int delta)throws SlickException{
    Input input = gc.getInput();



x += xSpeed;//////////////////////////////////////////CODE FOR COLLISION
y += ySpeed;//////////////////////////////////////////CODE FOR COLLISION

if(rectOne.intersects(rectTwo))///////////////////////CODE FOR COLLISION
{
xSpeed = 0;////////////////////////////CODE FOR COLLISION
ySpeed = 0;////////////////////////////CODE FOR COLLISION
}



    //up
    if(input.isKeyDown(Input.KEY_UP)){
        bucky = movingUp;//changes the image to his back
        buckyPositionY += 2;;//increase the Y coordinates of bucky (move him up)
        if(buckyPositionY>162){//if I reach the top 
            buckyPositionY -= 2;//stops any further movement in that direction
        }
    }

    //down
    if(input.isKeyDown(Input.KEY_DOWN)){
        bucky = movingDown;
        buckyPositionY -= 2;
        if(buckyPositionY<-550){
            buckyPositionY += 2;//basically change the direction if + make -
    }}
    //left
    if(input.isKeyDown(Input.KEY_LEFT)){
        bucky = movingLeft;
        buckyPositionX += 2;
        if(buckyPositionX>324){
            buckyPositionX -= 2;//delta * .1f
    }}
    //right
    if(input.isKeyDown(Input.KEY_RIGHT)){
        bucky = movingRight;
        buckyPositionX -= 2;
        if(buckyPositionX<-776){
            buckyPositionX += 2;
    }}



     //escape
    if(input.isKeyDown(Input.KEY_ESCAPE)){
        quit=true;
    }
    //when the menu is up
    if(quit==true){//is the menu on the screen
        if(input.isKeyDown(Input.KEY_R)){
            quit = false;//resumes the game, makes menu dissapear
        }
        if(input.isKeyDown(Input.KEY_M)){
            sbg.enterState(0);//takes you to the main menu
        }
        if(input.isKeyDown(Input.KEY_Q)){
            System.exit(0);//quits the game
        }
    }

}   


    public int getID(){
        return 1;
    }
}

Answer 1

作为先决条件，您的播放器类(或其父类(super class)之一)应该有几个字段来描述它们的速度(一对 x 速度和 y 速度的字段非常有效，尽管您需要触发来设置给定方向的玩家)。下面是一个带有 x 和 y 速度字段的简单播放器类的示例:

public class Player
{
     //coordinates of the player 
     private int x, y;

     //horizontal and vertical components of the player's speed.
     private int xSpeed, ySpeed; 

     //call a method similar to this one every time your player updates its position
     public void updatePosition()
     {
          x += xSpeed;
          y += ySpeed;
     }

     //Converts a speed and a direction (much easier to deal with)
     //to an x speed and a y speed (much easier for actually moving) 
     //and sets the player's motion
     public void setSpeedWithDirection(int speed, float direction)
     {
         xSpeed = Math.cos(direction) * speed;
         ySpeed = Math.sin(direction) * speed;
     }
}

为了使其真正反射(reflect)玩家的速度，每次玩家更新时将 x 速度添加到玩家的 x 坐标，并将 y 速度添加到玩家的 y 坐标。现在，碰撞发生时可能会发生很多事情。最简单的方法是通过将其 x 速度和 y 速度设置为零来停止播放器。然而，这看起来有点问题，因为无论玩家朝哪个方向前进，玩家都会停止移动。稍微好一点的方法是分析交叉点的形状(假设您使用的是 java.awt.Rectangle 您可以使用 intersection() 方法，几乎​​所有 Rectangle 类都有类似的东西)并确定是否应将 x 速度、y 速度或两者都设置为零。例如，如果交叉路口的宽度大于高度(x 轴大于 y 轴)，您可能应该将 y 速度设置为零，但 x 速度不受影响。如果你想让玩家转身(180 度)，只需翻转 x-speed 和 y-speed 的符号。如果您希望玩家“弹跳”而不是停止，请像之前的情况一样分析路口，但要反转速度而不是将其设置为零。这里有一些代码示例(可能不会完全按照写的那样工作，因为我不知道你的类是如何设置的):

//simple stop
if(rectOne.intersects(rectTwo))
{
    player.xSpeed = 0;
    player.ySpeed = 0;
}

//variable-axis stop
if(rectOne.intersects(rectTwo))
{
    //depending on Rectangle implementation may need to use other method
    Rectangle overlap = rectOne.intersection(rectTwo);
    if (overlap.height >= overlap.width)
    {
        player.xSpeed = 0;
    }
    if (overlap.width >= overlap.height)
    {
        player.ySpeed = 0;
    }
}

//simple turn-around (about face)
if(rectOne.intersects(rectTwo))
{
    player.xSpeed *= -1;
    player.ySpeed *= -1;
}

//bounce (variable-axis turn around)
if(rectOne.intersects(rectTwo))
{
    Rectangle overlap = rectOne.intersection(rectTwo);
    if (overlap.height >= overlap.width)
    {
        player.xSpeed *= -1;
    }
    if (overlap.width >= overlap.height)
    {
        player.ySpeed *= -1;
    }
}

请注意，无论您选择做什么，碰撞往往都很难顺利进行。我认为所有这些选项都是很好的起点，可以始终构建。我希望这会有所帮助。