PROGRAM H_H_DRAGON_MEDIAN   ! version by W.van Duyn 27th April 2004
SET MODE "color"
SET WINDOW 0,1199,0,903
SET BACKGROUND COLOR "white"
CLEAR
CALL init
END

SUB init
OPTION ANGLE degrees
PRINT "input: x try 400, y try 500"
INPUT x,y
PRINT "input: Size try 362,level try 12"
INPUT size,level
CLEAR
CALL backdrop2
LET lev =level
LET k=45
LET a=180
LET r=SQR(2)
LET d=size/r^level
SET COLOR 5
CALL axiom(d,lev,a,x,y,k)
END SUB

SUB axiom(d,lev,a,x,y,k)
CALL moveX(d,lev,a,x,y,k)
END SUB

SUB moveX(d,lev,a,x,y,k)
IF lev=0 THEN
EXIT IF
ELSE
CALL moveX(d,lev-1,a,x,y,k)
CALL turnLEFT(a,k)
CALL travelON(d,a,x,y)
CALL turnLEFT(a,k)
CALL moveY(d,lev-1,a,x,y,k)
END IF
END SUB

SUB moveY(d,lev,a,x,y,k)
IF lev=0 THEN
EXIT IF
ELSE
CALL moveX(d,lev-1,a,x,y,k)
CALL turnRIGHT(a,k)
CALL travelON(d,a,x,y)
CALL turnRIGHT(a,k)
CALL moveY(d,lev-1,a,x,y,k)
END IF
END SUB

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

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

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

SUB backDrop2   !optional sky backdrop for dragon
FOR ii=0 TO 910 STEP 10
SET COLOR MIX (col) 1-ii/910,1,ii/910
SET COLOR col
BOX AREA 0,1200,ii,ii+10
NEXT ii
END SUB