C SUBROUTINE TO FORM POLYGONS
C
      SUBROUTINE POLY(MODFIL)
      LOGICAL LP,INC,DEC,R3D,S3D,REP,INOUT
      INTEGER SIDES,RAD,XCENT,YCENT
      DIMENSION LIST(2)
      COMMON/FILE/LYNUM,LINE(4,200)
      COMMON/COORD/JX,JY
      COMMON/LTPEN/LP,IX,IY,IA
      COMMON/BOOKKP/LINSAV(200),MODSAV(50),ITAG
      DATA P,B,C,D,E,F,G,H,R,S,T,U/5H( 1X8,5HHRADI,5HUS =,,5HI3  ,,5H 3X
     17H,5HSIDES,5H =,I3,5H, 3X4,5HHPLUS,5H, 3X5,5HHMINU,5HS)   /
	DATA ACD,ADD,AED/5H(1X,4,5HHMORE,5H)    /
      DATA V,W/5H( 1X3,5HHOUT)/
	DATA AXA,AXB,AXC,AXD,AXE,AXF,ARG,ARH/5H(1X9H,5HREPLI,5HCATE,,
     15H3X6HR,5HETURN,5H,3X7H,5HRESTA,5HRT)  /
	DATA AXG,AXH,AXI,AXJ,AXK,AXL,AXM/5H(1X14,5HHRAND,
     15H0M CE,5HNTRES,5H,3X7H,5HREGUL,5HAR)  /
	DATA AZA,AZB,AZC,AZD,AZE,AZF,AZG,AZH,AZI,AZJ,AZK,AZL
     1/5H(1X2H,5HUP,3X,5H4HDOW,5HN,3X4,5HHLEFT,5H,3X5H,
     15HRIGHT,5H,3X8H,5H     ,5H   ,3,5HX6HRE,5HTURN)/
	DATA ABT,ACT,ADT/5H(1X,4,5HHDRAW,5H)    /
101	CALL TEXT(158,25,0,1,AXA)
	SIDES=0
      RAD=0
	XCENT=0
	YCENT=0
      PI=3.14159
	THET=00.
	R3D=.FALSE.
	S3D=.FALSE.
	REP=.FALSE.
	INOUT=.TRUE.
C
C ASSIGN CENTRE,SIDES AND RADIUS VALUES USING LIGHTPEN .
C
	CALL LITPEN(LP,IX,IY,IA)
30    CALL TEXT(128,128,5,1,P,RAD,SIDES)
      CALL TEXT(128,64,5,1,V)
32	INC=.FALSE.
	DEC=.FALSE.
39	LP=.FALSE.
40	IF(.NOT.LP)GO TO 40
C
C BRANCH TO GENERATE A POLYGON , OR TO SPECIFY A POLYGON .
C
	IF(IY.LE.80)GO TO 79
C
C SPECIFY : BRANCH TO INCREMENT OR DECREMENT PARAMETERS .
C
	IF((IX.GT.430).AND.(IX.LT.500))INC=.TRUE.
	IF((IX.GT.509).AND.(IX.LT.550))DEC=.TRUE.
C
C RADIUS
C
	IF((IX.GT.230).AND.(IX.LT.280))R3D=.TRUE.
C
C SIDES
C
	IF((IX.GT.370).AND.(IX.LT.415))S3D=.TRUE.
C
C DO THE ARITHMETIC
C
	IF(R3D.AND.INC)RAD=RAD+10
	IF(R3D.AND.DEC)RAD=RAD-10
	IF(S3D.AND.INC)SIDES=SIDES+1
	IF(S3D.AND.DEC)SIDES=SIDES-1
C
C DISPLAY NEW RADIUS,SIDES OR CENTRE VALUE .
C
	CALL TEXT(128,128,0,1,P,RAD,SIDES)
	CALL TEXT(128,128,5,1,P,RAD,SIDES)
	CALL TEXT(128,64,5,1,V)
	DO 3 I=1,25000
3	CONTINUE
	R3D=.FALSE.
	S3D=.FALSE.
	LP=.FALSE.
68	IF(.NOT.LP)GO TO 68
	IF((IX.GT.430).AND.(IX.LT.550))GO TO 32
	GO TO 39
C  
C ASSIGN CENTRE COORDINATES WITH SUBROUTINE CROSS  (LIGHTPEN
C AND FOLLOWING CROSS ).
C
79	CALL TEXT(128,128,0,1,P,RAD,SIDES)
	CALL TEXT(128,64,0,1,V)
	XCENT=512
	YCENT=512
986	CALL CROSS(.TRUE.,XCENT,YCENT)
	DO 987 K=1,1500
	DUM=SIN(3.1415)
987	CONTINUE
	CALL CROSS(.FALSE.,XCENT,YCENT)
	CALL TEXT(128,128,5,1,ACD)
	CALL TEXT(128,64,5,1,ABT)
	CALL LITPEN(LP,IX,IY,IA)
	LP=.FALSE.
988	IF(.NOT.LP)GO TO 988
	IF(IY.LT.80)GO TO 80
	IF((IY.GT.100).AND.(IY.LT.140))GO TO 986
C
C GENERATE THE POLYGON .
C
80	CALL TEXT(128,128,0,1,ACD)
	CALL TEXT(128,64,0,1,ABT)
	IF((SIDES.EQ.3).OR.(SIDES.EQ.5))GO TO 880
	ISAVEX=XCENT+RAD
	ISAVEY=YCENT
	GO TO 881
880	THET=PI/2.
	ISAVEX=XCENT
	ISAVEY=YCENT+RAD
881	S2DES=FLOAT(SIDES)
      R2D=FLOAT(RAD)
      RINC=(2.*PI)/S2DES
81    DO 90 I=1,SIDES
	THET=THET+RINC
      SJY=R2D*SIN(THET)
      SJX=R2D*COS(THET)
      JX=IFIX(SJX)+XCENT
      JY=IFIX(SJY)+YCENT
      LYNUM=LYNUM+1
      IF(LYNUM.GT.200) GO TO 90
      LINE(1,LYNUM)=ISAVEX
      LINE(2,LYNUM)=ISAVEY
      LINE(3,LYNUM)=JX
      LINE(4,LYNUM)=JY
      ISAVEX=JX
	ISAVEY=JY
	CALL CODER(LINE,LYNUM,LINSAV,MODFIL)
      MODFIL=0
90	CONTINUE
	CALL TEXT(128,128,0,1,P,RAD,SIDES)
	CALL TEXT(128,64,0,1,V)
C
C BRANCH TO REPLICATE OR RETURN OR RESTART .
C
	CALL LITPEN(LP,IX,IY,IA)
920	CALL TEXT(158,20,5,1,AXA)
	LP=.FALSE.
92	IF(.NOT.LP)GO TO 92
	IF((IX.GT.150).AND.(IX.LT.191).AND.(IY.LT.50))GO TO 93
	IF((IX.GT.279).AND.(IX.LT.323).AND.(IY.LT.50))GO TO 922
	IF((IX.GT.411).AND.(IX.LT.450).AND.(IY.LT.50))GO TO 101
922	CALL TEXT(158,20,0,1,AXA)
	RETURN
C
C REPLICATE WITH RANDOM CENTRES OR REGULAR?
C
93	CALL TEXT(158,20,0,1,AXA)
930	CALL TEXT(128,200,5,1,AXG)
933	LP=.FALSE.
	REP=.FALSE.
94	IF(.NOT.LP)GO TO 94
C
C RANDOM
C
	IF((IX.GT.120).AND.(IX.LT.161).AND.(IY.LT.220))GO TO 940
C
C REGULAR
C
	IF((IX.GT.320).AND.(IX.LT.370).AND.(IY.LT.220))GO TO 944
940	CALL TEXT(128,200,0,1,AXG)
	GO TO 79
944	CALL TEXT(128,200,0,1,AXG)
	CALL TEXT(128,64,5,1,AZA)
	LP=.FALSE.
95	IF(.NOT.LP)GO TO 95
C
C UP
C 
	IF((IX.GT.120).AND.(IX.LT.162).AND.(IY.LT.80))GO TO 96
C
C DOWN
C
	IF((IX.GT.180).AND.(IX.LT.228).AND.(IY.LT.80))GO TO 97
C
C LEFT
C
	IF((IX.GT.260).AND.(IX.LT.320).AND.(IY.LT.80))GO TO 98
C
C RIGHT
C
	IF((IX.GT.349).AND.(IX.LT.383).AND.(IY.LT.80))GO TO 99
C
C RETURN
C
	IF((IX.GT.558).AND.(IX.LT.591).AND.(IY.LT.80))GO TO 100
96	YCENT=YCENT+2*RAD
	GO TO 80
97	YCENT=YCENT-2*RAD
	GO TO 80
98	XCENT=XCENT-2*RAD
	GO TO 80
99	XCENT=XCENT+2*RAD
	GO TO 80
100	CALL TEXT(128,64,0,1,AZA)
	GO TO 922
	END