prologues := 3;
u=18mm;
textscale=u/12mm;
def cylinder =
begingroup;
save pmax,dmax,persp,persp_nt,arr;
save harrtop,harrbot,rarrlft,rarrrt;
save p,d;
save axisprotrusion;
save xax,yax,zax;
pmax = 3; dmax = 0;
persp_nt = 0.3;
persp = persp_nt*u;
arr = 0.2u; % how far to offset the arrows from the diagram
axisprotrusion = 1u; % how far do the axes protrude?
pair harrtop,harrbot,rarrlft,rarrrt; % endpoints for arrows
path p[],d[]; % original, dotted
pair xax[],yax[],zax[]; % x,y,z are taken; these are for the axes
% solid paths
p0 = (-1u,-1u)--(-1u,1u);
p1 = (1u,-1u)--(1u,1u);
p2 = fullcircle scaled u xscaled 2 yscaled (2*persp_nt) shifted (0,1u);
p3 = halfcircle scaled u xscaled 2 yscaled (2*persp_nt) rotated 180 shifted (0,-1u);
% dashed paths
d0 = halfcircle scaled u xscaled 2 yscaled (2*persp_nt) shifted (0,-1u);
% endpoints of dimension arrows
harrtop = (-1u-arr,1u);
harrbot = (-1u-arr,-1u);
rarrlft = (0,1u);
rarrrt = (1u,1u);
% actually draw
pickup pencircle scaled 1pt;
for i=0 upto pmax:
draw p[i];
endfor;
for i=0 upto dmax:
draw d[i] dashed evenly;
endfor;
drawdblarrow (harrtop..harrbot);
drawdblarrow (rarrlft..rarrrt);
label.lft(btex $h$ etex scaled textscale,.5[harrtop,harrbot]);
label.top(btex $r$ etex scaled textscale,.5[rarrlft,rarrrt]);
% x axis
xax0 = (0,0);
xax1 = point 1.5 of p3 shifted (0,1u);
xax2 = (1.+axisprotrusion/u)[xax0,xax1];
drawarrow (xax1..xax2);
draw xax0..xax1 dashed evenly;
label.rt(btex $y$ etex scaled textscale,xax2);
% y axis
yax0 = (0,0);
yax1 = (1u,0);
yax2 = (1u+axisprotrusion*0.5,0);
drawarrow (yax1..yax2);
draw yax0..yax1 dashed evenly;
label.top(btex $x$ etex scaled textscale,yax2);
% z axis
zax0 = (0,0);
zax1 = (0,1u);
zax2 = (0,1u+axisprotrusion);
drawarrow (zax1..zax2);
draw zax0..zax1 dashed evenly;
label.top(btex $z$ etex scaled textscale,zax2);
endgroup;
enddef;
beginfig(1)
cylinder;
currentpicture := currentpicture shifted (100,100); % avoid unwanted clipping
endfig;
end