code: function InfiniteCylinder3D( x , y , z , nx , ny , nz , r ) {
  	this.axis = new BoundVector3D( x , y , z , nx , ny , nz ).normalizeCheck() ;
  	this.r = + r ;
  }
docs: /*
  A InfiniteCylinder3D is a 3D line with a radius.
  
  axis: BoundVector3D.
  r: radius of the cylinder.