Betsy Ross Problem

Matlab学习中的betsy ross 问题。用matlab函数画1777年的美国国旗。

五角星绘制部分是自己想出来的方法去画上的。具体代码参考如下。

先是绘制矩形的函数

 function DrawRect(a,b,L,W,c)
 %Adda a Rectangle to the current window .Assumes hold is on.
 %The Rectangle has vertices (a,b),(a+L,b),(a,b+W),(a+L,b+W)
 %The c is color which is in the form of 'rgb vector' or one of the built-in
 %clolors such as 'r','g','y','b'
 x=[a,a+L,a+L,a];
 y=[b,b,b+W,b+W];
 fill(x,y,c);

然后是绘制五角星的代码

 function DrawStar(x1,y1,dr,c)
 %the center of the five-stars is  at (x1,y1)
 %the radius of five-stars
 %the color of the five-star
 dtheta=*pi/;
 hold on
 axis equal off
 j=:;
 %外部五个点
 x=x1+dr*cos(j*dtheta+pi/);
 y=y1+dr*sin(j*dtheta+pi/);
 %内部五个点
 xl=x1+dr*cos(j*dtheta+*pi/)/;
 yl=y1+dr*sin(j*dtheta+*pi/)/;
 %Seperately take the ten points into vector
 X=[x(),xl(),x(),xl(),x(),xl(),x(),xl(),x(),xl()];
 Y=[y(),yl(),y(),yl(),y(),yl(),y(),yl(),y(),yl()];
 %then draw it.
 fill(X,Y,c);

然后调用上面的两个函数，绘制整个旗帜

 function DrawFlag(a,b,L1,W1,L2,r1,r2)
 %Adds a -star,-stripe Colonial flag to the current
 %Figure window.Assumes hold id on
 %The flag is L1-by-W1 with lower left corner at(a,b).
 %The length fo the blue area is L2.The ring of stars has radius r1 and its
 %center is the center of the blue area
 %the radius of the individual stars is r2
 clc
 close all
 figure
 hold on
 s=W1/;
 axis equal off
 for k=:
     %Draw the kth stripe
     bk=b+(k-)*s;
     if rem(k,)==&&k<=
         DrawRect(a,bk,L1,s,'r');
     elseif rem(k,)==&&k<=
         DrawRect(a,bk,L1,s,'w');
     elseif rem(k,)==&&k>=
         DrawRect(a+L2,bk,L1-L2,s,'r');
     else DrawRect(a+L2,bk,L1-L2,s,'w');
     end
 end
 DrawRect(a,b+*s,L2,*s,'b');
 %draw star
 theta=*pi/;
 xc=(a+L2)/;
 yc=9.5*s;
 for k=:
     xr=xc+r1*cos(k*theta+pi/);
     yr=yc+r1*sin(k*theta+pi/);
     DrawStar(xr,yr,r2,'w');
 end
 hold off