Question

下面显示的代码是一个绿色的球，墙上有碰撞检测。

有什么方法可以改进吗？

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

public class Launcher extends Applet implements Runnable {

    private static final long serialVersionUID = 1L;

    private final int WIDTH = 50;
    private final int HIEGHT = 50;

    private int x = 5, velX = 1;
    private int y = 5, velY = 1;


    public void init() {

        this.setSize(800, 600);
    }

    public void run() {
        while (true) {

            if (x > this.getWidth() - WIDTH) {
                velX = -velX;
            }
            if (x < 0 + WIDTH / 2) {
                x = 0 + WIDTH / 2;
                velX = -velX;
            } else {
                x += velX;
            }
            if (y > this.getHeight() - HIEGHT) {

                velY = -velY;
            }
            if (y < 0 + HIEGHT / 2) {
                y = 0 + HIEGHT / 2;
                velY = -velY;
            } else {
                y += velY;
            }
            repaint();
            try {
                Thread.sleep(17);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public void start() {
        Thread thread = new Thread(this);
        thread.start();
    }

    public void stop() {
    }

    public void destroy() {
    }

    public void paint(Graphics g) {
        g.setColor(Color.GREEN);
        g.fillOval(x, y, WIDTH, HIEGHT);
    }
}

Answer 1

当你检查混合检查边界和绘图之间的顶部/左侧和中心坐标时，球从未到达左/顶部边界，但是会跨越右/下边界。我已经解决了这个问题，所以你只使用了上/左角（如果超过了边界就会这样做，那么就会重新计算它的位置，就像它已经反弹一样）。
重新绘制画布时，您正在清除所有内容并重新绘制。如果你覆盖update(Graphics)方法并且只是清除球的位置，那么重绘的次数就会少得多，而且（有点）更顺畅。

像这样：

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

public class Test extends Applet implements Runnable {

    private static final long serialVersionUID = 1L;

    private final int SIZE = 50;
    private final int VELOCITY = 1;

    private int x = 5, velX = VELOCITY;
    private int y = 5, velY = VELOCITY;


    @Override
    public void init() {
        this.setSize(800, 600);
    }

    @Override
    public void run() {
        while (true) {
            x += velX;
            if (x > this.getWidth() - SIZE) {
                x = 2*(this.getWidth() - SIZE)-x;
                velX = -velX;
            }
            else if (x < 0) {
                x = -x;
                velX = -velX;
            }

            y += velY;
            if (y > this.getHeight() - SIZE) {
                y = 2*(this.getHeight() - SIZE)-y;
                velY = -velY;
            }
            else if (y < 0) {
                y = -y;
                velY = -velY;
            }
            repaint();
            try {
                Thread.sleep(17);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void start() {
        new Thread(this).start();
    }

    @Override
    public void stop() {
    }

    @Override
    public void destroy() {
    }

    @Override
    public void update(Graphics g)
    {
        g.clearRect(
                x - VELOCITY,
                y - VELOCITY,
                SIZE+2*VELOCITY,
                SIZE+2*VELOCITY
        );
        paint(g);
    }

    @Override
    public void paint(Graphics g) {
        g.setColor(Color.GREEN);
        g.fillOval(x, y, SIZE, SIZE);
    }
}

具有墙壁的碰撞检测Java小程序无法正常工作

1 个答案: