PROGRAM Heighway_dragon   !© W.van Duyn 7th MAY 2004
SET MODE "color"
SET WINDOW 0,1199,0,903
SET COLOR 16
BOX AREA 0,1199,0,903 FLOOD 1,1
SET BACKGROUND COLOR "black"
SET COLOR "white"
PRINT"Heighway Dragon I.F.S."
PRINT"BY W.VanDuyn 2004 ©"
LET x=1
LET y=1
LET a=0
LET f=200
RANDOMIZE
SET COLOR 16
FLOOD 1,1
LET r=2
FOR n= 1 TO 10000000
LET a = INT(RND*2)+1
IF a =1 THEN
LET x1=(x/r)-(y/r)
LET y1=(x/r)+y/r
END IF
IF a=2 THEN
LET x1=-(x/r)-y/r+1
LET y1=(x/r)-y/r
END IF
SET COLOR MIX (a+100) 1,1-a/2,a/2
SET COLOR MIX (a+200) a/2,1,1-a/2
SET COLOR MIX (a+300) 1-a/2,a/2,1
IF mod(a,2) = 0 THEN SET COLOR a+100
IF mod(a,2) = 1 THEN SET COLOR a+200
LET x=x1
LET y=y1
IF n>10 THEN PLOT 600+f*x-300,450+f*y-150
NEXT n
END