How can I create sphere in this code?

X=(0:0.02:1);
Y=(0:0.02:1);
[x,y] = meshgrid(X,Y);
%z=rand(size(x))*1000;
%z=1e6*ones(size(x));
z=zeros(size(x));

x0=mean(X);
y0=mean(Y);
b_center1 = [0.2,0.8];
b_center2 = [0.6,0.2];
b_center3 = [0.4,0.55];
r1=0.1*max(X);
r2=0.1*max(X);
r3=0.1*max(X);

for i=1:length(X)
    for j=1:length(Y)
        dist = pdist([[X(i),Y(j)];b_center1]);
        if (dist < r1)
        z(i,j)=1;
        end
        
        dist = pdist([[X(i),Y(j)];b_center2]);
        if (dist < r2)
        z(i,j)=1;
        end
        
        dist = pdist([[X(i),Y(j)];b_center3]);
        if (dist < r3)
        z(i,j)=1;
        end
        
    end
end


surf(x,y,z)

Answer 1

[Ayush Gupta]

 The above code is not able to generate spheres primarily because in the workflow any point that is less than r1 is given a true value by giving it 1 whereas for a sphere the points should be all equidistant from a center. To plot a sphere with center at (a,b,c) and radius r, refer to the following code:

[x,y,z]  = sphere; 

x = x*r; 

y = y*r; 

z = z*r; 

figure 

surf(x+a,y+b,z+c)