Data commit

Task/Dragon-curve/QuickBASIC/dragon-curve.basic

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+REM Dragon curve
+REM SIN, COS in arrays for PI/4 multipl.
+DECLARE SUB Dragon (BYVAL Insize!, BYVAL Level%, BYVAL RQ%)
+DIM SHARED S(7), C(7), X, Y, RotQPi%
+CONST QPI = .785398163397448# ' PI / 4
+FOR I = 0 TO 7
+  S(I) = SIN(I * QPI)
+  C(I) = COS(I * QPI)
+NEXT I
+X = 112: Y = 70
+SCREEN 2: CLS
+CALL Dragon(128, 15, 1) ' Insize = 2^WHOLE_NUM (looks better)
+END
+
+SUB Dragon (BYVAL Insize, BYVAL Level%, BYVAL RQ%)
+  CONST SQ = 1.4142135623731# ' SQR(2)
+  IF Level% <= 1 THEN
+    XN = C(RotQPi%) * Insize + X
+    YN = S(RotQPi%) * Insize + Y
+    LINE (2 * X, Y)-(2 * XN, YN) ' For SCREEN 2 doubled x-coords
+    X = XN: Y = YN
+  ELSE
+    RotQPi% = (RotQPi% + RQ%) AND 7
+    CALL Dragon(Insize / SQ, Level% - 1, 1)
+    RotQPi% = (RotQPi% - RQ% * 2) AND 7
+    CALL Dragon(Insize / SQ, Level% - 1, -1)
+    RotQPi% = (RotQPi% + RQ%) AND 7
+  END IF
+END SUB