java球到线碰撞不起作用

Question

我正在研究Java中的游戏项目原型，我遇到了线路问题＆＃34;碰撞＆＃34;。我尝试了许多不同的方法让它发挥作用。有人可以帮我吗？我刚刚用完了想法，检查了一些像Mathworld这样的网站，但是当我尝试将这个数学重做为代码时，它并没有真正起作用。

class Ball {

    int x, y, radius, dx, dy;
    Color BallColor;

    public Ball(int x, int y, int radius, int dx, int dy, Color bColor) {
        this.x = x;
        this.y = y;
        this.radius = radius;
        this.dx = dx;
        this.dy = dy;
        BallColor = bColor;
    }
}

public class ball_1 extends Applet implements Runnable, MouseListener, MouseMotionListener {

    Ball ball1, ball2;
    int x1, x2, y1, y2,r1;
    int a, b;
    String msg = "";
    double c,d,e;


    @Override
    public void init() {
        this.setSize(800, 800);
        ball1 = new Ball(400, 70, 20, 4, 1, Color.green);
        ball2 = new Ball(40, 70, 20, 4, 1, Color.black);
        Thread t = new Thread(this);
        t.start();
        addMouseListener(this);
        addMouseMotionListener(this);
        Point p1 = new Point(x1,y1);
        Point p2 = new Point(x2,y2);
    }

    @Override
    public void paint(Graphics g) {
        g.setColor(ball1.BallColor);
        g.fillOval(ball1.x, ball1.y, ball1.radius, ball1.radius);
        g.setColor(ball2.BallColor);
        g.fillOval(ball2.x, ball2.y, ball2.radius, ball2.radius);
        g.drawLine(x1, y1, x2, y2);
        g.drawString(msg, 80, 80);
    }

    @Override
    public void run() {
        boolean run = true;
        while (run) {
            try {

                displacementOperation(ball2);
                lineCollision(ball1);
                ballCollision(ball1);
                ballCollision(ball2);
                Thread.sleep(40);
                repaint();
            } catch (Exception e) {
            }
            if (ball1.x >= 780 || ball1.y <= 0) {
                run = false;
                msg = "game over";
            }
            if (ball1.y >= 780 || ball1.x <= 0) {
                run = false;
                msg = "game over";
            }
        }
    }

    public void displacementOperation(Ball ball) {
        if (ball.y >= 780 || ball.y <= 0) {
            ball.dy = -ball.dy;
        }
        if (ball.x >= 780 || ball.x <= 0) {
            ball.dx = -ball.dx;
        }
        ball.y = ball.y - ball.dy;
        ball.x = ball.x - ball.dx;

    }

    public void lineCollision(Ball ball) {
        d = ((y2-y1)*(ball.radius) -(x2-x1)*(ball.radius) +x2*y1 -y2*x1)/((y2-y1)*(y2-y1))/2 + ((x2-x1)*(x2-x1))/2 ;
        if (ball.radius <= d){
            ball.dy = -ball.dy;
            ball.dx = -ball.dx;

        }

        ball.y = ball.y - ball.dy;
        ball.x = ball.x - ball.dx;


    }

    public void ballCollision(Ball ball) {
        a = (ball2.y - ball1.y) * (ball2.y - ball1.y) + (ball2.x - ball1.x) * (ball2.x - ball1.x);
        b = ((ball1.radius + 10) + (ball2.radius + 10)) / 2 * ((ball1.radius + 10) + (ball2.radius + 10)) / 2;
        if (a <= b) {
            ball.dy = -ball.dy;
            ball.dx = -ball.dx;

        }

        ball.y = ball.y - ball.dy;
        ball.x = ball.x - ball.dx;

    }

    @Override
    public void mouseClicked(MouseEvent e) {

    }

    @Override
    public void mousePressed(MouseEvent e) {
        x1 = e.getX();
        y1 = e.getY();
        repaint();
    }

    @Override
    public void mouseReleased(MouseEvent e) {

        x2 = e.getX();
        y2 = e.getY();
        repaint();
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        x2 = e.getX();
        y2 = e.getY();
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }