demi-tour dans l'espace

import solids;
import markers;
size(7.5cm,0);

currentprojection=orthographic(3,1,2);

triple vectaxe=(0,0,1);
triple poinaxe=(2,2,2);
triple vecu=(0,0,2);
transform3 r=rotate(180,poinaxe,poinaxe+vectaxe);
triple pM=poinaxe+(1,0,0);
triple pMp=r*pM;

dot(("$M$"),pM,S);
dot(("$M'$"),pMp,SE);
dot("$c$",poinaxe,S);

//limits(O,X+Y+Z);
//xaxis3(Label("$x$",1),Arrow3);
//yaxis3(Label("$y$",1),Arrow3);
//zaxis3(Label("$z$",1),Arrow3);

pen dotteddash=linetype("0 4 4 4"),
    pen2=.8bp+blue+dotted;
draw (poinaxe--pM,red+dotteddash);
draw (poinaxe--pMp,red+dotteddash);
draw((poinaxe+vectaxe)--(poinaxe-vectaxe),red+dotteddash);
path3 arcp = arc(poinaxe,pM,pMp,vectaxe,true);
draw(arcp,pen2);
path3 arctheta = shift(poinaxe)*scale3(.5)*shift(-poinaxe)*arcp;
draw(arctheta,Arrow3);
label("$\pi$",relpoint(arctheta,0.5),S);
draw(poinaxe--poinaxe+.3*vectaxe,Arrow3);
label("$\vec{e}$",poinaxe+.3*vectaxe,NW);

label("$D$",poinaxe+vectaxe,NW);

path3 plancentre(triple v1, triple v2, triple P) {return plane (2*v1,2*v2,P-v1-v2);};
path3 plan=plancentre((pM-poinaxe),(pMp-poinaxe),poinaxe);
draw(surface(plan),paleblue+opacity(.1));