;;;
;;;STRING_HYPOCYCLOID.LSP
(prompt "\nCurve-Stitching by AutoCAD - Hypocycloid.LSP")
(prompt "\nCommands:  hypocycloid   ")
(prompt "\n           ")
;;;Ref. Jon Millington
;;;		
;;;Takaya Iwamoto  Jan 01-03, 2004
;;;		July 3,2007	modified for web release
;;; Commands	hypocycloid  then input number of cusps
;;;		Oct 10,2007	renamed hypocycloid.lsp -->string_hypocycloid.lsp
;;;
(defun C:string_hypocycloid_old()
	(setq num_cusp (getint "\nNumber of cusp ? (def = 3)"))
	(if (= num_cusp nil) (setq num_cusp 3))
	(if (>= num_cusp 7) (C:case_7) ) 
	(setup_shypocycloid)
	(make_jpg)
	;;;execute the selected program
	(cond
		((= num_cusp 3)	 (C:deltoid) )
		((= num_cusp 4)	 (C:astroid) )
		((= num_cusp 5)	 (C:five_cusped) );;;to be implemented
		((= num_cusp 6)	 (C:six_cusped) )
		(t nil)
	);;;end of cond 
	(make_jpg)
	(make_jpg)
	(reset_sysvar)	
);;;STRING_HYPOCYCLOID_Old
;;;
;;;
(defun C:string_hypocycloid()			
	(setup_hypocycloid)				;set up 
	(make_jpg)
	(make_jpg)
	(setq ndiv (getint "\nNo of division (def = 36)"))
	(if (= ndiv nil) (setq ndiv 36))
	(alert "\nStart ?")
	(setq counter 0)
	(setq 	total_angle (* 2 pi)
		del_theta (/ total_angle ndiv)
		curve_pnt_old pnt_start
		n_cusp (fix rad_ratio)
		limit_angle (* pi (float (/ radius_in radius_out)))
		cur_theta 0.
		delay_time (fix (/ 18000 ndiv))
	)	
	(setq counter 1)
	(make_line_1 "layer7" 2 pnt_a pnt_b)
		(make_jpg)
	(while (< cur_theta limit_angle)
		(setq cur_theta (* counter del_theta)
			alpha (* c2 cur_theta)
			pnt_u (polar pnt_org (- pi alpha) ref_radius)
			pnt_um (polar pnt_org (+ pi alpha) ref_radius)
			pnt_p (polar pnt_org cur_theta ref_radius)
		)
;;if U & P coincide, then draw a tangent line on P and find V.
		(if (> (distance pnt_u pnt_p) 0.00001)
			(setq pnt_v (inters pnt_u pnt_p pnt_a pnt_b nil))
			(setq pnt_v (list (/ ref_radius (cos cur_theta)) 0.))
		)
		
		(make_line_1 "layer7" 2 pnt_u pnt_v)
			(make_jpg)
		(make_line_1 "layer7" 2 pnt_um pnt_v)
			(make_jpg)
		(setq counter (1+ counter))
		(command "_.delay" delay_time)
	);;;while loop
		(make_jpg)
		(make_jpg)
		(command "_.delay" delay_time)
	(alert "\nCopy this unit around the circle \nusing ARRAY command.") 
;;make a selection set of layer7
	(setq set_cusp (ssget "X" (list (cons 8 "layer7") ) ))
	(command "_.array" set_cusp "" "_P"  pnt_org n_cusp ""  "")
	
;
	(command "_.zoom" "_E")
	(command "_.regen")
	
	(reset_sysvar)
);;
;;;
;;;
(defun C:string_one_cusp()			
	(setup_hypocycloid)				;set up 
	(make_jpg)
	(make_jpg)
	(setq ndiv (getint "\nNo of division (def = 36)"))
	(if (= ndiv nil) (setq ndiv 36))
	(alert "\nStart ?")
	(setq counter 0)
	(setq 	total_angle (* 2 pi)
		del_theta (/ total_angle ndiv)
		curve_pnt_old pnt_start
		n_cusp (fix rad_ratio)
		limit_angle (* pi (float (/ radius_in radius_out)))
		cur_theta 0.
		delay_time (fix (/ 18000 ndiv))
	)	
	(setq counter 1)
	(make_line_1 "layer7" 2 pnt_a pnt_b)
		(make_jpg)
	(while (< cur_theta limit_angle)
		(setq cur_theta (* counter del_theta)
			alpha (* c2 cur_theta)
			pnt_u (polar pnt_org (- pi alpha) ref_radius)
			pnt_um (polar pnt_org (+ pi alpha) ref_radius)
			pnt_p (polar pnt_org cur_theta ref_radius)
		)
;;if U & P coincide, then draw a tangent line on P and find V.
		(if (> (distance pnt_u pnt_p) 0.00001)
			(setq pnt_v (inters pnt_u pnt_p pnt_a pnt_b nil))
			(setq pnt_v (list (/ ref_radius (cos cur_theta)) 0.))
		)
		
		(make_line_1 "layer7" 2 pnt_u pnt_v)
			(make_jpg)
		(make_line_1 "layer7" 2 pnt_um pnt_v)
			(make_jpg)
		(setq counter (1+ counter))
		(command "_.delay" delay_time)
	);;;while loop
		(make_jpg)
		(make_jpg)
		(command "_.delay" delay_time)

	(command "_.zoom" "_E")
	(command "_.regen")
	
	(reset_sysvar)
);;
;;;
;;;
(defun C:five_cusped()
	(alert "\nNot implemented yet.")
	(C:refresh_all)
	(exit)
)
;;;
;;;
(defun C:case_7()
	(alert "\nNot implemented yet.")
	(exit)
)
;;;
;;;
(defun C:deltoid()
	(setq num_sec (getint "\nNumber of section (def=36)"))
	(if (= num_sec nil) (setq num_sec 36))
	(command "_.divide" ref_circle num_sec)
	(setq EL1 (entnext ref_circle))

	(while EL1 (ssadd EL1 ss1)
		(setq EL1 (entnext EL1))
	);;;now ss1 has entity list of points on the circle
	(setq   del_theta (/ (* 2 pi) num_sec)
		nstep 1  n_section 100  color_id 2
	)
	(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) 
		IN 1 EN (ssname ss1 IN)
	) 
	(while (< IN num_sec)
		(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget EN)))))
		 IN (1+ IN) EN (ssname ss1 IN)
		)
	);;;end of WHILE LOOP
	;;;add the first element to the last
(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) )
	;;;now the N-th entry corresponds to pnt_N
	;;;define points A,B,C,D,E,F & G.
	(setq pnt_id 1)
	(repeat num_sec
		(set (read (strcat "pnt_" (itoa pnt_id))) (nth pnt_id pt_list))
		(setq pnt_id (1+ pnt_id))
	)
	(setq 	pnt_g (plt pnt_org pnt_6 3.0)
		pnt_a (plt pnt_org pnt_6 2.0)
		pnt_b (inters pnt_org pnt_6 pnt_34 pnt_1 nil)
		pnt_c (inters pnt_org pnt_6 pnt_32 pnt_2 nil)
		pnt_d (inters pnt_org pnt_6 pnt_30 pnt_3 nil)
		pnt_e (inters pnt_org pnt_6 pnt_28 pnt_4 nil)
		pnt_f (inters pnt_org pnt_6 pnt_26 pnt_5 nil)
	)
	(command "_.point" pnt_a)
	(command "_.point" pnt_b)
	(command "_.point" pnt_c)
	(command "_.point" pnt_d)
	(command "_.point" pnt_e)
	(command "_.point" pnt_f)
	(command "_.point" pnt_g)

	(setq start nil end nil
		start (list pnt_36 pnt_34 pnt_32 pnt_30 pnt_28 pnt_26 pnt_24
				pnt_22 pnt_20 pnt_18 pnt_16 pnt_14 pnt_12)
		end   (list pnt_a pnt_b pnt_c pnt_d pnt_e pnt_f pnt_g
				pnt_f pnt_e pnt_d pnt_c pnt_b pnt_a)
		line_num 0 
	)
	(repeat 13
		(setq p_start (nth line_num start) 
			p_end (nth line_num end)
		)
		(make_line_1 "layer2" color_id p_start p_end)
		;(slow_line n_section "layer2" color_id p_start p_end)
		
		(setq line_num (1+ line_num))
		(make_jpg)
		(command "_.delay" 250)
	)
	;;;point connection for the first cusp
	; 36 a   ;;;Tangent	 34 b	 32 c	 30 d	 28 e	 26 f
	; 24 g   ;;;Diameter	 22 f	 20 e	 18 d	 16 c	 14 b
	; 12 a   ;;;Tangent
	
	;;;copy this cusp mode using "Polar" array command
	(alert "\nCopy this Cusp to other 2 positions")
	(entdel outer_circle)
	(command "_.delay" 500)
	(command "_.array" "all" "" "P" pnt_org 3 "" "Y")
	
	
	
	(make_jpg)
	(command "_.delay" 250)
	
	;(alert "\nWant to make - Four Deltoid -  ?")
	(if (= (Yes_or_No "Want to make - Four Deltoid -  ?  def is OK ") "_Y")
		(command "_.array" "all" "" "P" '(-3 0) 4 "" "Y")
	)
	(command "_.zoom" "E")
	(command "_.regen")
	(make_jpg)
	(make_jpg)
	(reset_sysvar)	
);;;deltoid
;;;
;;;function to find the number to subtract from
;;;
(defun find_bound (test_num / low high test upper_bound)
	(setq low 0 high num_sec test "no" upper_bound ref_num)
	(while (= test "no")
		(if (and (>= test_num low) (< test_num high))
			(setq test "yes" upper_bound high)
			(setq low high high (+ high ref_num))
		)
	);;;end of while loop
	(prin1 upper_bound)
);;;FIND_BOUND		
;;;
(defun setup_shypocycloid()
	(setup_sysvar)
	(setvar "PDMODE" 32)
	(setvar "PDSIZE" -1)

	(setq ref_rad 1.0 pnt_org '(0 0) ref_rad2 (* 2 ref_rad)
		r_factor  (/ (float num_cusp) (- num_cusp 2))
		ref_rad3 (* r_factor ref_rad) ss1 nil ss1 (ssadd)
		pt_list nil
	)
	(make_circle_1 "0" 8 pnt_org ref_rad3)
		(setq outer_circle (entlast))
	(make_circle_1 "0" 8 pnt_org ref_rad)
	(setq ref_circle (entlast))
	(command "_.zoom" "E")
	(command "_.regen")
);;;SETUP_sHYPOCYCLOID
;;;
(defun C:test2()
	(setup_shypocycloid)
	(setq num_sec (getint "\nNumber of section (def=72)"))
	(if (= num_sec nil) (setq num_sec 72))
	(setq   del_theta (/ (* 2 pi) num_sec)
		nstep 0  n_section 50  color_id 2
	)
	(setq num_cusp (getint "\nNumber of cusp ? (def = 1)"))
	(if (= num_cusp nil) (setq num_cusp 1))
	(setq ref_num (/ num_sec (1+ num_cusp)) )

	(repeat  num_sec
		(setq start_angle (* nstep del_theta)
			p_start (polar pnt_org start_angle ref_rad)
			end_angle (* (1+ num_cusp) del_theta (rem nstep ref_num))
			p_end (polar pnt_org end_angle ref_rad)
		)
		(make_line_1  "0" color_id p_start p_end)
		(setq  nstep (1+ nstep) )
	);;;outer loop
	(reset_sysvar)	
);;;TEST2
;;;
;;;
(defun C:astroid()
	;(setup_shypocycloid)
	(make_jpg)
	(setq num_sec (getint "\nNumber of section (def=36)"))
	(if (= num_sec nil) (setq num_sec 36))
	(command "_.divide" ref_circle num_sec)
	(setq EL1 (entnext ref_circle))

	(while EL1 (ssadd EL1 ss1)
		(setq EL1 (entnext EL1))
	);;;now ss1 has entity list of points on the circle
	(setq   del_theta (/ (* 2 pi) num_sec)
		nstep 1  n_section 100  color_id 2
	)
	
	(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) 
		IN 1 EN (ssname ss1 IN)
	) 
	(while (< IN num_sec)
		(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget EN)))))
		 IN (1+ IN) EN (ssname ss1 IN)
		)
	);;;end of WHILE LOOP
	;;;add the first element to the last
(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) )
	;;;now the N-th entry corresponds to pnt_N
	;;;define points A,B,C,D,E,F & G.
	(setq pnt_id 1)
	(repeat num_sec
		(set (read (strcat "pnt_" (itoa pnt_id))) (nth pnt_id pt_list))
		(setq pnt_id (1+ pnt_id))
	)
	(setq 	pnt_45  (polar pnt_org (* 4.5 del_theta) 1.0)
		pnt_2223 (polar pnt_org (* 22.5 del_theta) 1.0)
		pnt_g (plt pnt_org pnt_45 2.0)
		pnt_a (plt pnt_org pnt_45 (sqrt 2.0))
		pnt_b (inters pnt_org pnt_45 pnt_33 pnt_1 nil)
		pnt_c (inters pnt_org pnt_45 pnt_30 pnt_2 nil)
		pnt_d (inters pnt_org pnt_45 pnt_27 pnt_3 nil)
		pnt_e (inters pnt_org pnt_45 pnt_24 pnt_4 nil)
		;pnt_f (inters pnt_org pnt_6 pnt_26 pnt_5 nil)
	)
	(command "_.point" pnt_a)
	(command "_.point" pnt_b)
	(command "_.point" pnt_c)
	(command "_.point" pnt_d)
	(command "_.point" pnt_e)
	;(command "_.point" pnt_f)
	(command "_.point" pnt_g)

	(setq start nil end nil
		start (list pnt_36 pnt_33 pnt_30 pnt_27 pnt_24  
				pnt_21 pnt_18 pnt_15 pnt_12 pnt_9)
		end   (list pnt_a pnt_b pnt_c pnt_d pnt_e 
				  pnt_e pnt_d pnt_c pnt_b pnt_a)
		line_num 0 
	)
	(repeat 10
		(setq p_start (nth line_num start) 
			p_end (nth line_num end)
		)
		(make_line_1 "layer2" color_id p_start p_end)
		;(slow_line n_section "layer2" color_id p_start p_end)
		(setq line_num (1+ line_num))
		(make_jpg)
		(command "_.delay" 250)
	)

		
	;;;copy this cusp mode using "Polar" array command
	(alert "\nCopy this Cusp to other 3 positions")
	(entdel outer_circle)
	(command "_.delay" 500)
	(command "_.array" "all" "" "P" pnt_org 4 "" "Y")
	(make_jpg)
	(command "_.delay" 250)
	(command "_.zoom" "E")
	(command "_.regen")
	(make_jpg)
	(reset_sysvar)	
);;;Astroid
;;;
;;;
(defun C:six_cusped()
	(setq num_sec (getint "\nNumber of section (def=72)"))
	(if (= num_sec nil) (setq num_sec 72))
	(command "_.divide" ref_circle num_sec)
	(setq EL1 (entnext ref_circle))

	(while EL1 (ssadd EL1 ss1)
		(setq EL1 (entnext EL1))
	);;;now ss1 has entity list of points on the circle
	(setq   nstep 1  n_section 100  color_id 2
	        pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) 
		IN 1 EN (ssname ss1 IN)
	) 
	(while (< IN num_sec)
		(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget EN)))))
		 IN (1+ IN) EN (ssname ss1 IN)
		)
	);;;end of WHILE LOOP
	;;;add the first element to the last
(setq   pt_list (append pt_list (list (cdr (assoc 10 (entget (ssname ss1 0)))))) )
	;;;now the N-th entry corresponds to pnt_N
	;;;define points A,B,C,D,E,F & G.
	(setq pnt_id 1)
	(repeat num_sec
		(set (read (strcat "pnt_" (itoa pnt_id))) (nth pnt_id pt_list))
		(setq  pnt_id (1+ pnt_id))
		
	)
	(setq 	pnt_g (plt pnt_org pnt_6 1.5)
		pnt_a (plt pnt_org pnt_6 (/ 2. (sqrt 3)) )
		pnt_b (inters pnt_org pnt_6 pnt_67 pnt_1 nil)
		pnt_c (inters pnt_org pnt_6 pnt_62 pnt_2 nil)
		pnt_d (inters pnt_org pnt_6 pnt_57 pnt_3 nil)
		pnt_e (inters pnt_org pnt_6 pnt_52 pnt_4 nil)
		pnt_f (inters pnt_org pnt_6 pnt_47 pnt_5 nil)
	)
	(command "_.point" pnt_a)
	(command "_.point" pnt_b)
	(command "_.point" pnt_c)
	(command "_.point" pnt_d)
	(command "_.point" pnt_e)
	(command "_.point" pnt_f)
	(command "_.point" pnt_g)

	(setq start nil end nil
		start (list pnt_72 pnt_67 pnt_62 pnt_57 pnt_52 pnt_47 pnt_42
				pnt_37 pnt_32 pnt_27 pnt_22 pnt_17 pnt_12)
		end   (list pnt_a pnt_b pnt_c pnt_d pnt_e pnt_f pnt_g
			    pnt_f pnt_e pnt_d pnt_c pnt_b pnt_a)
		line_num 0 
	)
	(repeat 13
		(setq p_start (nth line_num start) 
			p_end (nth line_num end)
		)
		(make_line_1 "layer2" color_id p_start p_end)
		;(slow_line n_section "layer2" color_id p_start p_end)
		(setq line_num (1+ line_num))
		(make_jpg)
		(command "_.delay" 250)
	)
	;;;copy this cusp mode using "Polar" array command
	(alert "\nCopy this Cusp to other 5 positions")
	(entdel outer_circle)
	(command "_.delay" 500)
	(command "_.array" "all" "" "P" pnt_org 6 "" "Y")
	(command "_.delay" 250)
	(command "_.zoom" "E")
	(command "_.regen")
	(make_jpg)
	(make_jpg)
	(reset_sysvar)	
);;;six_cusped
;;;
;;;
(defun C:string_hypocycloid_model()			
	(setup_hypocycloid)				;set up 
	(make_jpg)
	(make_jpg)
	(setq ndiv (getint "\nNo of division (def = 36)"))
	(if (= ndiv nil) (setq ndiv 36))
	(alert "\nStart ?")
	(setq counter 0)
	(setq 	total_angle (* 2 pi)
		del_theta (/ total_angle ndiv)
		curve_pnt_old pnt_start
		n_cusp (fix rad_ratio)
		last_step (1- (fix (/ ndiv (* 2 n_cusp))) )
	)	
	(setq counter 0)
	
	(repeat last_step
		(setq cur_theta (* counter del_theta)
			pnt_tmp (polar pnt_org cur_theta 1.0))
		(get_value)
		(if (>= counter 1) 
			(progn
				(clear_lines)
				(setq x_new (+ (* c1 (cos cur_theta)) (* radius_in (cos (* c2 cur_theta))))
					y_new (- (* c1 (sin cur_theta)) (* radius_in (sin (* c2 cur_theta))))
					curve_pnt_new (list x_new y_new)
				)
				(make_line_1 "layer4" 4 curve_pnt_old curve_pnt_new)
				(setq curve_pnt_old curve_pnt_new)
			)
		);;end if
			
		(command "_.insert" "hypo_cycle" pnt_new 1.0 1.0 angle_disk1)
		(command "explode" (entlast))
		(setq counter (1+ counter))
		(command "_.delay" 250)
	);;;repeat loop
	(make_circle_1 "layer4" 8 pnt_org ref_radius)
		(setq ref_circle (entlast))
	(make_pt "0" 0 pnt_org)
	(setq pnt_r (polar pnt_org cur_theta radius_out)
		pnt_w (shift_pnt pnt_new '(1. 0))
		pnt_q pnt_new
		pnt_s curve_pnt_old	
		pnt_p (polar pnt_org cur_theta ref_radius)
		alpha (angle pnt_q pnt_s)
		theta (angle pnt_org pnt_r)
		beta (+ pi alpha)
		pnt_t (polar pnt_org alpha ref_radius)
		pnt_m (polar pnt_org alpha radius_out)
		pnt_u (polar pnt_org beta ref_radius)
		pnt_n (polar pnt_org beta radius_out)
		pnt_v (inters pnt_p pnt_s pnt_org pnt_x nil)
	)
;;make points & lines
	(make_pt "0" 0 pnt_v)
	(make_pt "0" 0 pnt_w)
	(make_pt "0" 0 pnt_u)
	(make_pt "0" 0 pnt_t)
	(make_pt "0" 0 pnt_a)
	(make_pt "0" 0 pnt_p)
	(make_pt "0" 0 pnt_q)
	(make_pt "0" 0 pnt_r)





	(make_line_1 "0" 8 pnt_org in_center)
	(make_line_1 "0" 8 pnt_org pnt_r)
	(make_line_1 "0" 8 pnt_q pnt_w)
	(make_line_1 "0" 8 pnt_m pnt_u)
	(make_line_1 "0" 8 pnt_r pnt_m)
	(make_line_1 "0" 2 pnt_u pnt_v)
	;(make_line_1 "0" 8 pnt_n pnt_r)
;;mark_id
	(mark_id pnt_org "O" 3 chr_size)
	(mark_id pnt_p "P" 2 chr_size)
	(mark_id pnt_q "Q" 2 chr_size)
	(mark_id pnt_r "R" 1 chr_size)
	(mark_id pnt_s "S" 1 chr_size)
	(mark_id pnt_w "W" 1 chr_size)
	(mark_id pnt_a "A" 3 chr_size)
	(mark_id pnt_b "B" 1 chr_size)
	(mark_id pnt_t "T" 4 chr_size)
	(mark_id pnt_u "U" 2 chr_size)
	(mark_id pnt_v "V" 4 chr_size)
	(mark_id pnt_m "M" 3 chr_size)
	;(mark_id pnt_n "N" 3 chr_size)
;;divide circles- ref_circle & out_circle
	;(command "_.divide" ref_circle ndiv)
	;(command "_.divide" out_circle ndiv)
;;mark_angle
	(mark_angle pnt_s pnt_q pnt_w 0.3 "a" 0.175 4)
	(mark_angle pnt_b pnt_org pnt_r 0.4 "q" 0.175 1)
	(mark_angle pnt_m pnt_org pnt_b 0.5 "a" 0.175 1)
	(mark_angle pnt_b pnt_org pnt_u 0.65 "b" 0.175 2)
	(mark_angle pnt_u pnt_org pnt_a 0.5 "a" 0.175 3)

	(command "_.zoom" "_E")
	(command "_.regen")
	
	(reset_sysvar)
);;
;;;
;;;
;;;
;compute translation & angle values from pnt_tmp
(defun get_value( / theta )
	(setq theta (angle out_center pnt_tmp))
	(setq angle_disk1 (- (rtd (* (- rad_ratio 1.0) theta))))
	(setq pnt_new (polar out_center theta rad_dif))
)
;clear construction lines
(defun clear_lines( / block_set n nminus index )
	;(setq block_set (ssget "X" (list (cons -4 "<OR")(cons 8 "layer1")(cons 8 "layer8")
	;				  (cons -4 "OR>")) ))
	(setq block_set (ssget "X" (list  (cons 8 "layer8")) ) )
	(setq n (sslength block_set))
	;(setq nminus (- n 3))
	;repeat for all circle & line  elements
	(setq index 0)
	;(repeat nminus  
	(repeat n     
            (entdel (ssname block_set index)) 
	    (setq index (1+ index))
	)
);;;CLEAR_LINES	
;;;
;;;
;setup_hypocycloid
(defun setup_hypocycloid( /  set_hypo  fraction
				x_upper x_lower pnt_upper pnt_lower
			)
	(setup_sysvar)
	(setvar "PDMODE" 32)
	(setvar "PDSIZE" -2)
	(setvar "OSMODE" 0)
	(setq radius_out (getreal "\nradius of outer circle ? (def = 3.0)")
		radius_in (getreal "\nRadius of inner circle ? (def=1.0)"))
	(if (= radius_in nil) (setq radius_in 1.0))
	(if (= radius_out nil) (setq radius_out 3.0))	
	;(setup_hypo_dialog)
	(setq rad_ratio (/ (float radius_out) (float radius_in)) 
		n_cusp (fix rad_ratio)
		radius_in (/ (float radius_out) rad_ratio)
		rad_dif (- radius_out radius_in)
		ref_radius (- radius_out (* 2 radius_in))
		c1 rad_dif
		c2 (/ rad_dif radius_in)
		pnt_org '(0 0)
		out_center '(0 0)  in_center (list rad_dif 0.0)
		pnt_start (list  radius_out  0.0  )
		pnt_a (list (- ref_radius) 0)
		pnt_b pnt_start
		fraction (* radius_in 0.2) 
		x_upper (+ (car pnt_start) fraction)
		x_lower (- (car pnt_start) fraction)
		pnt_upper (list x_upper fraction)
		pnt_lower (list x_lower (- fraction))
		chr_size 0.20
	)
 	(make_circle_1 "0" 0 out_center radius_out)
		(setq out_circle (entlast))
	(make_circle_1 "layer4" 8 pnt_org ref_radius)
		(setq ref_circle (entlast))
	(make_line_1 "0" 8 pnt_a pnt_b)
;define block named "hypo_cycle"
	;layer 8
		(make_circle_1 "layer8" 8 in_center radius_in)
		(make_pt "layer8" 8 in_center)
	;layer 2
		(make_pt "layer2" 2 pnt_start)
	;layer 3
		(make_line_1 "layer3" 3 pnt_start in_center)

	(command "_.zoom" "_EXTENT")
	(command "_.regen")
	;select entity set for block
	(setq set_hypo (ssget "X" (list (cons -4 "<OR")(cons 8 "layer2")(cons 8 "layer3")(cons 8 "layer8")
					  (cons -4 "OR>")) ))
	(command "_.block" "hypo_cycle" in_center set_hypo "")	;block definition

);;;SETUP_HYPOCYCLOID