#declare tx0=0   ;
#declare ty0=-2 ;
#declare tz0=0   ;

#declare tx1=0    ;
#declare ty1=2    ;
#declare tz1=0    ;

#declare tx2=1     ;
#declare ty2=5      ;
#declare tz2=0     ;

#declare tx3=0      ;
#declare ty3=7       ;
#declare tz3=0      ;

#declare tx4=-1      ;
#declare ty4=5      ;
#declare tz4=0      ;

#declare tx5=0.5      ;
#declare ty5=2.5      ;
#declare tz5=0      ;


#declare tuyau =
union{
#declare tt=1.5       ;
  #declare ltx=tx1    ;
  #declare lty=ty1    ;
  #declare ltz=tz1    ;

#while (tt<5)
  #declare p0=    (1-tt)*(2-tt)*(3-tt)*(4-tt)*(5-tt)/120 ;
  #declare p1=    tt*(2-tt)*(3-tt)*(4-tt)*(5-tt)/24      ;
  #declare p2=    tt*(tt-1)*(3-tt)*(4-tt)*(5-tt)/12      ;
  #declare p3=    tt*(tt-1)*(tt-2)*(4-tt)*(5-tt)/12      ;
  #declare p4=    tt*(tt-1)*(tt-2)*(tt-3)*(5-tt)/24      ;
  #declare p5=    tt*(tt-1)*(tt-2)*(tt-3)*(tt-4)/120     ;

  #declare tx=tx0*p0+tx1*p1+tx2*p2+tx3*p3+tx4*p4+tx5*p5  ;
  #declare ty=ty0*p0+ty1*p1+ty2*p2+ty3*p3+ty4*p4+ty5*p5  ;
  #declare tz=tz0*p0+tz1*p1+tz2*p2+tz3*p3+tz4*p4+tz5*p5  ;

  cylinder { <ltx,lty,ltz>,<tx,ty,tz>,0.23 texture { Silver_Texture } }
  #declare tt=tt+0.25          ;
  #declare ltx=tx              ;
  #declare lty=ty              ;
  #declare ltz=tz              ;
#end
 }