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
1 function DrawRect(a,b,L,W,c) 2 %Adda a Rectangle to the current window .Assumes hold is on. 3 %The Rectangle has vertices (a,b),(a+L,b),(a,b+W),(a+L,b+W) 4 %The c is color which is in the form of 'rgb vector' or one of the built-in 5 %clolors such as 'r','g','y','b' 6 x=[a,a+L,a+L,a]; 7 y=[b,b,b+W,b+W]; 8 fill(x,y,c);
然后是绘制五角星的代码
1 function DrawStar(x1,y1,dr,c) 2 %the center of the five-stars is at (x1,y1) 3 %the radius of five-stars 4 %the color of the five-star 5 dtheta=2*pi/5; 6 hold on 7 axis equal off 8 j=0:4; 9 %外部五个点 10 x=x1+dr*cos(j*dtheta+pi/2); 11 y=y1+dr*sin(j*dtheta+pi/2); 12 %内部五个点 13 xl=x1+dr*cos(j*dtheta+2*pi/3)/2; 14 yl=y1+dr*sin(j*dtheta+2*pi/3)/2; 15 %Seperately take the ten points into vector 16 X=[x(1),xl(1),x(2),xl(2),x(3),xl(3),x(4),xl(4),x(5),xl(5)]; 17 Y=[y(1),yl(1),y(2),yl(2),y(3),yl(3),y(4),yl(4),y(5),yl(5)]; 18 %then draw it. 19 fill(X,Y,c);
然后调用上面的两个函数，绘制整个旗帜
1 function DrawFlag(a,b,L1,W1,L2,r1,r2) 2 %Adds a 13-star,13-stripe Colonial flag to the current 3 %Figure window.Assumes hold id on 4 %The flag is L1-by-W1 with lower left corner at(a,b). 5 %The length fo the blue area is L2.The ring of stars has radius r1 and its 6 %center is the center of the blue area 7 %the radius of the individual stars is r2 8 clc 9 close all 10 figure 11 hold on 12 s=W1/13; 13 axis equal off 14 for k=1:13 15 %Draw the kth stripe 16 bk=b+(k-1)*s; 17 if rem(k,2)==1&&k<=6 18 DrawRect(a,bk,L1,s,'r'); 19 elseif rem(k,2)==0&&k<=6 20 DrawRect(a,bk,L1,s,'w'); 21 elseif rem(k,2)==1&&k>=6 22 DrawRect(a+L2,bk,L1-L2,s,'r'); 23 else DrawRect(a+L2,bk,L1-L2,s,'w'); 24 end 25 end 26 DrawRect(a,b+6*s,L2,7*s,'b'); 27 %draw star 28 theta=2*pi/13; 29 xc=(a+L2)/2; 30 yc=9.5*s; 31 for k=0:12 32 xr=xc+r1*cos(k*theta+pi/2); 33 yr=yc+r1*sin(k*theta+pi/2); 34 DrawStar(xr,yr,r2,'w');5 35 end 36 hold off