Data commit

Task/Dragon-curve/MSX-Basic/dragon-curve.basic

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+10 REM Dragon curve
+20 REM SIN, COS in arrays for PI/4 multipl.
+30 DIM S(7),C(7)
+40 QPI=ATN(1):SQ=SQR(2)
+50 FOR I=0 TO 7
+60 S(I)=SIN(I*QPI):C(I)=COS(I*QPI)
+70 NEXT I
+80 LEVEL=15
+90 INSIZE=128:REM 2^WHOLE_NUM (looks better)
+100 X=80:Y=70
+110 ROTQPI=0:RQ=1
+120 DIM R(LEVEL)
+130 SCREEN 2
+140 GOSUB 200
+150 OPEN "GRP:" FOR OUTPUT AS #1
+160 DRAW "BM 0,184":PRINT #1,"Hit any key to exit."
+170 IF INKEY$="" THEN 170
+180 CLOSE #1
+190 END
+200 REM Dragon
+210 ROTQPI=ROTQPI AND 7
+220 IF LEVEL>1 THEN GOTO 280
+230 YN=S(ROTQPI)*INSIZE+Y
+240 XN=C(ROTQPI)*INSIZE+X
+250 LINE (X,Y)-(XN,YN)
+260 X=XN:Y=YN
+270 RETURN
+280 INSIZE=INSIZE*SQ/2
+290 ROTQPI=(ROTQPI+RQ)AND 7
+300 LEVEL=LEVEL-1
+310 R(LEVEL)=RQ:RQ=1
+320 GOSUB 200
+330 ROTQPI=(ROTQPI-R(LEVEL)*2)AND 7
+340 RQ=-1
+350 GOSUB 200
+360 RQ=R(LEVEL)
+370 ROTQPI=(ROTQPI+RQ)AND 7
+380 LEVEL=LEVEL+1
+390 INSIZE=INSIZE*SQ
+400 RETURN