----------  Sierpinski Triangle (Chaos Game) ----------------

TO CHAOS
HT  setc 69
MAKE "POINTS [[-220 -100] [0 -100] [-110 80]]
MAKE "TEMP :POINTS
MOVETO ( FIRST FIRST :POINTS ) ( LAST FIRST :POINTS )
MAKE "TEMP BF :TEMP
REPEAT 2 [pointto FIRST :TEMP FD Howfar XCOR YCOR ( FIRST FIRST :TEMP ) ( 
LAST FIRST :TEMP ) MAKE "TEMP BF :TEMP]
pointto FIRST :POINTS FD Howfar XCOR YCOR ( FIRST FIRST :POINTS ) ( LAST 
FIRST :POINTS )
REPEAT 3500 [MAKE "TARGET ( 1 + RANDOM 3 ) MAKE "DEST PICKout :TARGET 
:POINTS pointto :DEST PU FD ( 0.5  *  Howfar XCOR YCOR ( FIRST :DEST ) ( 
LAST :DEST ) ) PD DOT  XCOR YCOR]
finis
END


TO pickout :N :LIST
REPEAT :N [MAKE "ANS FIRST :LIST MAKE "LIST BF :LIST]
OP :ANS
END


to pointto :list
make "x first :list make "y last :list
newturtle "temp
ht
moveto :x :y
tto "t1  towards "temp
remove "temp
end


to dot :x :y
setsh 60 stamp
end


TO Howfar :X1 :Y1 :X2 :Y2
MAKE "DELX2 ( :X1 - :X2 )  *  ( :X1 - :X2 )
MAKE "DELY2 ( :Y1 - :Y2 )  *  ( :Y1 - :Y2 )
OP SQRT ( :DELX2 + :DELY2 )
END





----------  Sierpinski Triangle (Fractal Curve) ----------------


TO SIERPINSKICURVE :SIDE :LEVEL
; [USE SIERPINSKICURVE 3500 7]

MOVETO (220) -100
SETH -90
SIERP :SIDE :LEVEL  -1
END


TO SIERP :SIDE :LEVEL :DIRECTION
IF :LEVEL = 0 [FD :SIDE STOP]
LT :DIRECTION  *  60
SIERP (:SIDE / 3) (:LEVEL - 1) (-1 * :direction)
RT :DIRECTION  *  60
SIERP (:SIDE / 3) (:LEVEL - 1) ( :DIRECTION )
RT :DIRECTION  *  60
SIERP (:SIDE / 3) (:LEVEL - 1) (-1 * :direction)
LT :DIRECTION  *  60
END



TO MOVETO :X :Y
PU SETX :X SETY :Y PD
END