PROGRAM Generalized_von_Koch ! © W.van Duyn April 18th 2004
SET MODE "color"
SET WINDOW 0,1199,0,903     !tune to suit monitor
SET BACKGROUND COLOR "white"
CLEAR
CALL init
END

SUB init
PRINT "input position try x, 200 and y, 600"
INPUT x,y
PRINT "input side try 400, level try 4, dimension try 6."
INPUT size,level,ak
CLEAR
SET COLOR "blue"
FLOOD 1,1
SET COLOR "white"
LET a=0
LET k=360/ak
For ii = 1 TO ak
CALL shift(level,size,x,y,a,ak,k)
NEXT ii
SET COLOR "black"
FLOOD 1,1
END SUB

SUB shift(level,size,x,y,a,ak,k)
LET r=3
LET d=size/(r^level)
LET lev=level
CALL move(d,lev,a,x,y,k,ak)
CALL turnRIGHT(a,k)
END SUB

SUB move(d,lev,a,x,y,k,ak)
IF lev=0 THEN
CALL travelON(d,a,x,y)
EXIT IF
ELSE
CALL move(d,lev-1,a,x,y,k,ak)
CALL turnLEFT(a,k)
CALL move(d,lev-1,a,x,y,k,ak)
FOR p=1 TO ak-2
CALL turnRIGHT(a,k)
CALL move(d,lev-1,a,x,y,k,ak)
NEXT p
CALL turnLEFT(a,k)
CALL move(d,lev-1,a,x,y,k,ak)
END IF
END SUB

SUB travelOn(d,a,x,y)
OPTION ANGLE degrees
LET dx=d*cos(a)
LET dy=d*sin(a)
LET x2=x+round(dx)
LET y2=y+round(dy)
PLOT x,y;x2,y2
LET x=x+dx
LET y=y+dy
END SUB

SUB turnLEFT(a,k)
LET a=a+k+180
END SUB

SUB turnRIGHT(a,k)
LET a=a+k
END SUB