dim = 60;
[xi, yi, zi] = meshgrid(1:dim, 1:dim, 1:dim);
dist = (xi - 30).^2 + (yi - 30).^2 + (zi - 30).^2;

v = zeros(size(xi));
v(dist < 100) = 1;
v = v + 1;

fid = fopen('spherebox.bin', 'wb');
aa = fwrite(fid, v, 'uchar');
fclose(fid);
