JAVA笛卡尔曲线

效果图如下：

import java.applet.*;
import java.awt.*;

public class Descartes extends Applet 
{
    int AppletWidth,AppletHeight;
    Image OffScreen;
    Graphics drawOffScreen;
    public void init()
    {
        setBackground(Color.black);    //设置背景为黑色
        AppletWidth = getSize().width * 2; //获取applet的宽度
        AppletHeight = getSize().height * 2; //获取appplet的高度
        OffScreen = createImage(AppletWidth,AppletHeight); //创建一副使用了双缓冲技术的不可见的画布
        drawOffScreen = OffScreen.getGraphics();
    }
    public void paint(Graphics g)
    {
        //设置前景色为白色
        drawOffScreen.clearRect(0,0,AppletWidth,AppletHeight);
        drawOffScreen.setColor(Color.white);
        double x,y,r;
        for(int i=0; i<=90 ; i++)
        {
            for(int j=0; j<=90; j++)
            {
                r=Math.PI / 45 * i * ( 1 - Math.sin(Math.PI / 45 * j)) * 18;
                x = r * Math.cos(Math.PI / 45 * j) * Math.sin(Math.PI / 45 * i)+AppletWidth / 2;
                y = -r*Math.sin(Math.PI / 45 * j) + AppletHeight / 4;
                drawOffScreen.fillOval((int)x,(int)y,2,2); //绘制椭圆形
            }
        }
        g.drawImage(OffScreen,0,0,this); //生成图片
    }
}