function L = ladder(c)
qd1 = quarter_disk([-.1; 0; 10]);
qd2 = quarter_disk([.1; 0; 10]);
b = bars([0; 0; 10], 10, .2);
L = [qd1, qd2, b];

function QD = quarter_disk(c)
QD = [];
for th = 0:(pi/200):(pi/2)
    QD = [QD, c+[0; sin(th); -cos(th)]];
end

function P = bars(c, n, w)
P = [];
for th = 0:(pi/(2*n)):pi/2
    for x = (-w/2):(w/200):(w/2)
        P = [P, c+[x; sin(th); -cos(th)]];
    end
end
