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
     }
 }