计算机图形学--利用Java实现正负法画圆

import javax.swing.*; import java.awt.*; class SetPixel extends JPanel { Color color; int radius; public SetPixel(){ color = Color.blue; radius = 100; } public void paintComponent(Graphics g){ g.setColor(color); pnarc(g,radius); wangge(g,300,300); } void pnarc(Graphics g ,int radius){ int x0=150,y0=150; int x,y,f; x = 0; y = 0 + radius; f = 0; while (y>0){ g.drawLine(x+x0,y+y0, x+x0, y+y0); g.drawLine(x+x0,-y+y0, x+x0, -y+y0); g.drawLine(-x+x0,-y+y0, -x+x0, -y+y0); g.drawLine(-x+x0, y+y0, -x+x0, y+y0); if (f>0){ f = f - 2 * y + 1; y -- ; }else{ f = f + 2 * x + 1 ; x ++ ; } } if (y==0) g.drawLine(x+x0,y+y0, x+x0, y+y0); g.drawLine(x+x0,-y+y0, x+x0, -y+y0); g.drawLine(-x+x0,-y+y0, -x+x0, -y+y0); g.drawLine(-x+x0, y+y0, -x+x0, y+y0); } void wangge(Graphics g,int x1,int x2){ for (int i=0;i<=x1;i++){ g.drawLine(0,i*10,x1,i*10); } for (int i=0;i<=x2;i++){ g.drawLine(i*10,0,i*10,x2); } } }