10 REM TWISTER-DEMO
15 REM https://8bitshack.org/post/twister/
20 GR
30 FOR A2 = 1 TO 360 STEP 3
40 AM = 120+COS(A2*0.0174533)*100
50 AN = -3.141593+SIN(A2*0.0174533)*3.141593
60 FOR Y = 1 TO 39 STEP 2
65 FV = Y*4/AM+AN
70 X1 = 8*SIN(FV)
80 X2 = 8*SIN(FV+1.570796)
95 X3 = -X1
105 X4 = -X2
108 COLOR = 0: HLIN 10,30 AT Y
109 COLOR = 1
110 IF X1 < X2 THEN HLIN 20+X1,20+X2 AT Y: GOTO 130
120 IF X3 < X4 THEN HLIN 20+X3,20+X4 AT Y
130 COLOR = 2 : IF X2 < X3 THEN HLIN 20+X2,20+X3 AT Y: GOTO 150
140 IF X4 < X1 THEN HLIN 20+X4,20+X1 AT Y
150 NEXT Y
160 NEXT A2
170 GOTO 30