(prompt "\nAngle Trisection by AutoCAD - SPIRAL_A.LSP")
(prompt "\nCommands:  TEST_1 TEST_2 SPIRAL_3 SPIRAL_4 ")
(prompt "\nCommands:  DIVIDE_ANGLE  ")
(prompt "\n           ")
;----------------------------------------------------------
;;	by Takaya Iwamoto
;;	Nov 27, 2006	fixed bug in spiral_4
;;	SPIRAL_A.LSP
;;    Spiral by Archimedes
;;
;;
;;SPIRAL_A.LSP
;;					;Spiral_1-- Archimedian
;;	click left mouse to define a point
(defun c:TEST_1 ()
  (setvar "PDMODE" 32)
  (setvar "PDSIZE" -1)
  (setup_sysvar)
  (setq	const_a	   (/ 2.0 pi)	two_pi	   (* 2.0 pi)
	x_left	   '(-3.0 0)	x_right	   '(4.25 0)
	y_up	   '(0 2.5)	y_down	   '(0 -3.0)
	pnt_origin '(0 0)
  )
  (setq pnt_old pnt_origin)
  
  (make_line_1 "0" 8 x_left x_right)
  (make_line_1 "0" 8 y_down y_up)
  (make_circle_1 "0" 2 pnt_origin 1.0)
  (make_circle_1 "0" 3 pnt_origin 2.0)

  (command "_.zoom" "_EXTENT")
  (setvar "OSMODE" 512)

  (regapp "my_point")
  (make_point "0" 0 '(0 0) "O" 3 0.20)
  (make_point "0" 0 '(1 0) "P" 1 0.20)
  (make_point "0" 0 '(2 0) "Q" 1 0.20)
  
  (while (setq pnt_temp	(getpoint
		  "\nPick a point on the inner circle. Hit return key to quit"))
    (setq theta (angle pnt_origin pnt_temp))
    (if	(> (distance pnt_origin pnt_temp) 1.5)
      (setq theta (+ theta two_pi))
    )
    (setq radius  (* const_a theta)
	  pnt_new (polar pnt_origin theta radius)
    )
    (make_pt "0" 4 pnt_new)
    (make_line_1 "0" 1 pnt_old pnt_new)
    (setq pnt_old pnt_new)
  )
)
;;
;;
;;	Continuous mouse pick		;Spiral_2-- Archimedian
(defun c:TEST_2 ()
  (setvar "PDMODE" 32)
  (setvar "PDSIZE" -1)
  (setup_sysvar)
  (setq	const_a	   (/ 2.0 pi)	x_left	   '(-1 0)
	x_right	   '(1 0)	y_up	   '(0 1)
	y_down	   '(0 -1)	pnt_origin '(0 0)
	pnt_old	   pnt_origin
  )

  (make_line_1 "0" 8 '(0 -3.25) '(0 1.25))
  (make_line_1 "0" 8 '(-2.25 0) '(4.25 0))
  (regapp "my_point")
  (make_point "0" 0 '(0 0) "O" 3 0.15)
  (make_point "0" 0 '(1 0) "P" 1 0.15)
  (make_point "0" 0 '(0 1) "Q" 1 0.15)
  (make_point "0" 0 '(-2 0) "R" 3 0.15)

  (make_point "0" 0 '(0 -3) "S" 1 0.15)
  (make_point "0" 0 '(4 0) "T" 2 0.15)

  (command "_.zoom" "_EXTENT")
  (setvar "OSMODE" 8)
  (setq	answer
	 (getpoint
	   "Place the cursor at P, then press left mouse to start.\n
	Press left mouse or return key to terminate."
	 )
  )

;;; while loop to pick a point continuously

  (make_line_1 "0" 2 pnt_origin '(1 0))
  (setq line_ent (entlast))
  (while (and (setq key (grread T)) (= (car key) 5))
    (setq pnt_temp (cadr key))

    (setq theta	  (angle pnt_origin pnt_temp)
	  radius  (* const_a theta)
	  pnt_new (polar pnt_origin theta radius)
    )
    (entdel line_ent)
    (make_line_1 "0" 4 pnt_old pnt_new)
    (make_line_1 "0" 2 pnt_origin pnt_new)
    (setq line_ent (entlast)
	  pnt_old  pnt_new
    )
  )					;while
  (entdel (entlast))
  (reset_sysvar)
)
;;
;;
					;Spiral_3-- Archimedian
(defun c:SPIRAL_3 ()
  (setvar "PDMODE" 32)
  (setvar "PDSIZE" -1)
  (setup_sysvar)
  (setq n_cycle (getreal "\nHow many rounds (def = 2 )"))
	(if (= n_cycle nil) (setq n_cycle 2))
  (setq	const_a	   (/ 2.0 pi)	pnt_org '(0 0)
	theta_end  (* (* 2 n_cycle)  pi)	theta_old  0.0
	pnt_old	   pnt_org chr_size 0.15
  )
  (setq del_theta (getreal "\nInput angle step in radian<0.01>:"))
  (if (<= del_theta 0.0) (setq del_theta 0.01))
  (while (<= (setq theta_new (+ theta_old del_theta)) theta_end)
    (setq radius  (* const_a theta_new)
	  pnt_new (polar pnt_org theta_new radius)
    )
    (make_line_1 "0" 4 pnt_old pnt_new)
    (setq pnt_old   pnt_new
	  theta_old theta_new
    )
  )
;;;;
  (setq pl_entity (entlast))
  (command "_pedit" pl_entity "Y" "_Join" "all" "" "_X")
  (reset_sysvar)
  (make_pt "0" 1 pnt_org)
  (make_line_1 "0" 8 '(-2.25 0) '(1.25 0))
  (make_line_1 "0" 8 '(0 1.25) '(0 -1.25))
  (regapp "my_point")
  (make_point "0" 0 '(0 0) "O" 4 chr_size)
  (make_point "0" 0 '(1.25 0) "B" 1 chr_size)
  (command "_.zoom" "_EXTENT")
  (command "_ucsicon" "off")
)
;;;
;;;
;;;Use Archimedes' Spiral to trisect a given angle
;;;					;Spiral_4-- Archimedian
(defun c:SPIRAL_4 ()
  (setvar "PDMODE" 32)
  (setvar "PDSIZE" -1)
  (setup_sysvar)
  (setq	const_a	   (/ 2.0 pi)	pnt_org '(0 0)
	theta_end  (* 2.0 pi)	del_theta  0.001
	theta_old  0.0	pnt_old	   pnt_org
  )
  (while (<= (setq theta_new (+ theta_old del_theta)) theta_end)
    (setq radius  (* const_a theta_new)
	  pnt_new (polar pnt_org theta_new radius)
    )
    (make_line_1 "0" 4 pnt_old pnt_new)
    (setq pnt_old   pnt_new
	  theta_old theta_new
    )
  )
;;;;
  (setq pl_entity (entlast))
  (command "_pedit" pl_entity "Y" "_Join" "all" "" "_X")
	(setq pl_total (entlast))

  (make_pt "0" 1 pnt_org)
  (make_line_1 "0" 8 '(-2.25 0) '(4.25 0))
  (make_line_1 "0" 8 '(0 1.25) '(0 -3.25))
  (command "_.zoom" "_EXTENT")

  (c:divide_angle)			;execute trisection
  (reset_sysvar)
  (command "_ucsicon" "off")
)

;;
;;   DIVIDE_ANGLE
;(defun c:DIVIDE_ANGLE (/	     line_end	   one_third
;		       line_fortest  end_point	   radius_circle
;		       begin_arc     end_arc	   arc_ent
;		       trisect
;		      )
(defun c:DIVIDE_ANGLE ( )
  (setq chr_size 0.15)
  (setq line_end (getpoint '(0 0)
	       "Pick a point to define an angle crossing the spiral:")
  )(terpri)
	
  (make_line_1 "0" 2  line_end pnt_org)
  ;(mark_point line_end -0.3 0.3 "A" chr_size)	
  (command "_.delay" 500)
  (setq one_third (/ 1.0 3.0))
	
  (alert "\nTrim the line using spiral as delimiter")
  (command "_.trim" pl_total "" line_end "")
 	
  	(setq line_fortest (entlast))
  (command "_.delay" 500)
  
  (setq end_point (cdr (assoc 10 (entget line_fortest)))
       radius_circle (/ (get_length line_fortest) 3)
	trisect (* radius_circle pi 0.5)
  )
  ;(make_pt "0" 0 pnt_org )
 ; (make_line_1 "0" 8 line_end end_point)

  (mark_point end_point -0.3 0.3 "P" chr_size)
  ;(mark_point pnt_org 0.3 -1. "O" chr_size)
(alert "\nDivide the yellow line into 3 equal length")
  (command "_.divide" line_fortest 3)
	(command "_.delay" 1000)
  (setq	begin_arc (polar pnt_org trisect radius_circle )
	end_arc	  (plt pnt_org end_point one_third)
  )
;(alert "\nDraw an arc from x-axis to the end")
  (command "_.arc" "c" '(0 0) begin_arc end_arc)
  (setq arc_ent (entlast))
  (command "_.delay" 1000)

 (setq arc_ent (entget (entlast)))
   
  (make_line_1 "0" 1 pnt_org begin_arc )
  
  (make_point "0" 0 begin_arc "E" 1 0.15)
;;;display the result
 (mark_point line_end -0.3 0.3 "A" chr_size)
 (mark_point '(3.75 0) 0. 0. "B" chr_size)
 (make_line_1 "0" 8 line_end end_point)
 (mark_point pnt_org 0.3 -1. "O" chr_size)
  (setq original (cdr (assoc 51 arc_ent))
	ang_aob (angtos original 0 10)
   	ang_eob (angtos trisect 0 10)
   	result_aob (strcat "Angle AOB = " ang_aob " deg")
   	result_eob (strcat "Angle EOB = " ang_eob " deg" )
   	ang_ratio (rtos (/ original trisect ) 1 10)
   	result (strcat "Angle ratio = " ang_ratio)
  )
  (textdisplay result_aob '(0.05 -0.75)  chr_size 0.)
  (textdisplay result_eob '(0.05 -1.25)  chr_size 0.)
  (textdisplay result     '(0.05 -1.75)  chr_size 0.)
  (command "_.zoom" "_Extent")
)
;;--------------------------------------------------------------------------
(princ)