import graph; // Uncomment the following 2 lines to support pdf animations: // usepackage("animate"); // settings.tex="pdflatex"; import animation; size(0,200); defaultpen(3); dotfactor=4; pair wheelpoint(real t) { return (t+cos(t),-sin(t)); } guide wheel(guide g=nullpath, real a, real b, int n) { real width=(b-a)/n; for(int i=0; i <= n; ++i) { real t=a+width*i; g=g--wheelpoint(t); } return g; } real t1=0; real t2=t1+2*pi; animation a; draw(circle((0,0),1)); draw(wheel(t1,t2,100),linetype("0 2")); yequals(Label("$y=-1$",1.0),-1,extend=true,linetype("4 4")); xaxis(Label("$x$",align=3SW),0); yaxis("$y$",0,1.2); pair z1=wheelpoint(t1); pair z2=wheelpoint(t2); dot(z1); dot(z2); int n=10; real dt=(t2-t1)/n; for(int i=0; i <= n; ++i) { save(); real t=t1+dt*i; draw(circle((t,0),1),red); dot(wheelpoint(t)); a.add(); // Add currentpicture to animation. restore(); } erase(); // Merge the images into a gif animation. a.movie(BBox(0.25cm),loops=10,delay=250); // Merge the images into a pdf animation. // label(a.pdf(BBox(0.25cm),delay=250,"controls",multipage=false));