for(t=[],W=400,c=N=0;N<21;N++)t[N]=[W-20*N,0,20*N,0];draw=a=>{c++||createCanvas(W,W),background(W),t.find(a=>t.find(t=>{[q,r,s]=t,b=a[1]+=atan2(x=a[0]-q,y=a[2]-s)/(1+mag(x,y)),a[3]=W-2*dist(u=a[0]+=cos(b)/3,v=a[2]+=sin(b)/3,q,s),stroke(a),line(u,v,q,s)}))};//#つぶやきProcessing