Getting a list of polyline vertices using LISP

Here is one way to generate a list of polyline vertices using lisp. This function requires one argument, a polyline entity. The polyline can be the old style POLYLINE entity (2D or 3D), or it can be an LWPOLYLINE entity.

(defun getcoords (ent)
  (vlax-safearray->list
    (vlax-variant-value
      (vlax-get-property
	(vlax-ename->vla-object ent)
	"Coordinates"
      )
    )
  )
)

Example:

(getcoords (car (entsel)))

This function will return a list of coordinates. If the polyline is a LWPOLYLINE entity, the list will be in the form of (x y x y x y x y), and the number of vertices can be determined by dividing the length of the list by 2.

If the polyline is a POLYLINE entity (2D or 3D), then the list will be in the form of (x y z x y z x y z), and the number of vertices can be determined by dividing the length of the list by 3.

A sample of the output is shown below:
(-3.65553 2.56916 -0.83241 5.477 3.9698 3.23796 6.50188 4.54649 10.0235 2.71455 14.8257 6.78553)