;; | ----------------------------------------------------------------------------
;; | GE_GetPoint@DistOnLine
;; | ----------------------------------------------------------------------------
;; | Function : Returns a point on a line at a specified distance from the first
;; |            point of the line.
;; | Argument : 'pt1' - First point of the line (can be a 3d point too)
;; |            'pt2' - Last point of the line  (can be a 3d point too)
;; |            'd'   - Distance of point along line
;; | Returns  : an interpolated 3d point between 'pt1' and 'pt2' at a distance
;; |            of 'd' from 'pt1' along 'pt2'
;; | Updated  : July 25, 2002
;; | e-mail   : rakesh.rao@4d-technologies.com 
;; | Web      : www.4d-technologies.com
;; | ----------------------------------------------------------------------------


(defun GE_GetPoint@DistOnLine ( pt1 pt2 d / len Z Z1 Z2 dZ dH ang pt )

(setq
	Z1  (caddr pt1)
	Z2  (caddr pt2)
	len (distance pt1 pt2)
	ang (angle pt1 pt2)
	dZ  (/ (* d (- Z2 Z1)) len)
	dH  (sqrt (- (MI_Sqr d) (MI_Sqr dZ)))
	pt  (polar pt1 ang dH)
	pt  (list (car pt) (cadr pt) (+ Z1 dZ))
)
pt
)