;            <<<<Courtesy of PC-AUG BBS * 602-952-0638 * 24 HR *>>>>
;           
;USAGE:      (load "ARCTLN") COMMAND:ATL
;
;            Copyright (c) 1990 -- Fred Bertagnolli -- Engramme Engr.
;            for PC-AUG BBS. Donation of $15.00 would be appreciated. 
;            NOT FOR COMMERCIAL OR BUSINESS USE, OF ANY KIND.
;            For info contact Fred Bertagnolli at 801-621-3634
;
;FUNCTION:   ARCTLN draws an arc TANGENT to a line.
;
;INPUTS:     PICK AN EXISTING LINE, NEAR ITS END POINT
;            Enter Delta (CENTRAL ANGLE) of new ARC
;            <LEFT> or <RIGHT> curvature from end of line     
;            RADIUS OF NEW ARC
;  
;            ATL does the rest!  
;
;COMMENTS:   This is a difficult construct with standard methods.
;            Use to construct SURVEYOR STYLE ARCS to lines.
;
(DEFUN C:ATL (/ AU E E1 BP PH EP CA LR RD LA ANG CTR SA)
(SETVAR "OSMODE" 0)
(SETVAR "FLATLAND" 1)
(SETQ
 AU (GETVAR "AUNITS")
 E (ENTSEL "PICK LINE NEAR ARC START: ")
 E1 (ENTGET (CAR E))
 BP (OSNAP (CADR E) "END")
 PH (/ PI 2.0)
 EP (CDR (ASSOC '10 E1))
)
(SETQ EP (IF (EQUAL BP EP) (CDR (ASSOC '11 E1)) EP))
(SETVAR "AUNITS" 1) ;DMS INPUT
(SETQ CA (GETANGLE "\nDelta <DdM'S.s> :"))
(INITGET 1 "L R")
(SETQ LR (GETKWORD "\nCURVE <L>eft or <R>ight: "))
(INITGET (+ 1 2 4))
(SETQ RD (GETDIST "\nRADIUS: "))
(IF (= LR "R") (SETQ PH (- PH)))
(SETQ LA (ANGLE EP BP))
(SETQ ANG (+ PH LA))
(SETQ CTR (POLAR BP ANG RD))
(SETQ SA (ANGTOS CA 1 15))
(IF (= LR "R")(SETQ SA (STRCAT "-" SA)))
(COMMAND "ARC" BP "C" CTR "A" SA)
(SETVAR "AUNITS" AU)
(SETVAR "FLATLAND" 1)
(PRINC)
)