Points inside a tube

Generates a list of random points that lie inside a tube

function random_points_inside_tube(r,r2,h,n)=

          [for(i=[1:n])tube_point(r,r2,h)];

function tube_point(r,r2,h)=

let (p=[

rands(-r,r,1)[0],

rands(-r,r,1)[0],

rands(0,h,1)[0] ],

d=(pow(p.x,2) + pow(p.y,2) ))

 d > pow(r,2)||d < pow(r2,2)?tube_point(r,r2,h):p;


p=random_points_inside_tube(50,30,100,1000);
for(t=p)translate(t) sphere(4);
echo(p);