matlab的bresenham画圆

function [X,Y]=Bresenhamcircle(x0,y0,r)
X=ones(1,1000);
Y=X;                                      %坐标向量，用于存储绘制的点的坐标
x1=X;x2=X;x3=X;x4=X;x5=X;x6=X;x7=X;x8=X;
y1=Y;y2=Y;y3=Y;y4=Y;y5=Y;y6=Y;y7=Y;y8=Y;  %将圆对称划分为8个部分，分别用xi，yi记录坐标
D=ones(1,1002);                           %判别向量
i=1;
x1(1)=x0;x2(1)=x0+r;x3(1)=x2(1);x4(1)=x0;x5(1)=x4(1);x6(1)=x0-r;x7(1)=x6(1);x8(1)=x1(1);
y1(1)=y0+r;y2(1)=y0;y3(1)=y2(1);y4(1)=y0-r;y5(1)=y4(1);y6(1)=y0;y7(1)=y6(1);y8(1)=y1(1);     %初始条件
xd=2^(1/2)/2*r+x0;
while x1(i)<xd
    i=i+1;
    x1(i)=x1(i-1)+1;y2(i)=y2(i-1)+1;y3(i)=y3(i-1)-1; x4(i)=x4(i-1)+1; x5(i)=x5(i-1)-1;y6(i)=y6(i-1)-1;y7(i)=y7(i-1)+1; x8(i)=x8(i-1)-1;         %计长方向总加1
    D(i)=2*(y1(i-1)-y0-(r^2-(x1(i)-x0)^2)^(1/2))-1;
    if D(i)<0
        y1(i)=y1(i-1);x2(i)=x2(i-1);x3(i)=x3(i-1);y4(i)=y4(i-1);y5(i)=y5(i-1);x6(i)=x6(i-1);x7(i)=x7(i-1); y8(i)=y8(i-1);
    end
    if D(i)>=0
        y1(i)=y1(i-1)-1;x2(i)=x2(i-1)-1;x3(i)=x3(i-1)-1;y4(i)=y4(i-1)+1;y5(i)=y5(i-1)+1;x6(i)=x6(i-1)+1;x7(i)=x7(i-1)+1; y8(i)=y8(i-1)-1;
    end
end
X(1:i)=x1(1:i);X(i+1:2*i)=x2(1:i);X(2*i+1:3*i)=x3(1:i);X(3*i+1:4*i)=x4(1:i);X(4*i+1:5*i)=x5(1:i);X(5*i+1:6*i)=x6(1:i);X(6*i+1:7*i)=x7(1:i);X(7*i+1:8*i)=x8(1:i);
Y(1:i)=y1(1:i);Y(i+1:2*i)=y2(1:i);Y(2*i+1:3*i)=y3(1:i);Y(3*i+1:4*i)=y4(1:i);Y(4*i+1:5*i)=y5(1:i);Y(5*i+1:6*i)=y6(1:i);Y(6*i+1:7*i)=y7(1:i);Y(7*i+1:8*i)=y8(1:i);
X=X(1:8*i);Y=Y(1:8*i);
a=0:pi/2000:2*pi;
x=x0+r*cos(a);
y=y0+r*sin(a);
plot(x,y,'k');
legend('实际图像');hold on;
plot(X,Y,'r.');