2016 Update

Task/Dragon-curve/ZX-Spectrum-Basic/dragon-curve.zx

@@ -0,0 +1,29 @@
+10 LET level=15: LET insize=120
+20 LET x=80: LET y=70
+30 LET iters=2^level
+40 LET qiter=256/iters
+50 LET sq=SQR (2): LET qpi=PI/4
+60 LET rotation=0: LET iter=0: LET rq=1
+70 DIM r(level)
+75 GO SUB 80: STOP
+80 REM Dragon
+90 IF level>1 THEN GO TO 200
+100 LET yn=SIN (rotation)*insize+y
+110 LET xn=COS (rotation)*insize+x
+120 PLOT x,y: DRAW xn-x,yn-y
+130 LET iter=iter+1
+140 LET x=xn: LET y=yn
+150 RETURN
+200 LET insize=insize/sq
+210 LET rotation=rotation+rq*qpi
+220 LET level=level-1
+230 LET r(level)=rq: LET rq=1
+240 GO SUB 80
+250 LET rotation=rotation-r(level)*qpi*2
+260 LET rq=-1
+270 GO SUB 80
+280 LET rq=r(level)
+290 LET rotation=rotation+rq*qpi
+300 LET level=level+1
+310 LET insize=insize*sq
+320 RETURN