(glCoreVertex3f x0 y0 z0 . xtra)

glCoreVertex3f simulate OpenGL 3D vertex call.

Parameter	Description
x0	x coordinate of Vertex
y0	y coordinate of Vertex
z0	z coordinate of Vertex
xtra	Optional: tx and ty

From DemoCube the custom rendering function:

(let loop ((vs cube_vertices)(cs cube_colors))
  (if (> (length vs) 0) (begin
    (glCoreColor (car cs))
    (glCoreBegin GL_TRIANGLE_STRIP)
    (map (lambda (l) (apply glCoreVertex3f l)) (car vs))
    (glCoreEnd)
    (loop (cdr vs) (cdr cs)))))