24 lines
743 B
Plaintext
24 lines
743 B
Plaintext
10 HGR :FULLSCREEN = PEEK (49234)
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20 HCOLOR= 3
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30 FOR N = 3 TO 279 STEP 4
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40 X1 = 276:Y1 = 189:X2 = N:Y2 = 1: GOSUB 100"PLOT LINE"
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50 NEXT N
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60 FOR N = 3 TO 191 STEP 3
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70 X1 = 276:Y1 = 190:X2 = 2:Y2 = N: GOSUB 100"PLOT LINE"
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80 NEXT N
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90 END
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100 DX = ABS (X2 - X1)
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110 SX = SGN (X2 - X1)
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120 DY = - ABS (Y2 - Y1)
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130 SY = SGN (Y2 - Y1)
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140 ERR = DX + DY
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150 FOR WHILE = 0 TO 1 STEP 0
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160 HPLOT X1,Y1
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170 IF X1 = X2 AND Y1 = Y2 THEN RETURN
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180 E2 = 2 * ERR
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190 IF E2 > = DY AND X1 = X2 THEN RETURN
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200 IF E2 > = DY THEN ERR = ERR + DY:X1 = X1 + SX
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210 IF E2 < = DX AND Y1 = Y2 THEN RETURN
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220 IF E2 < = DX THEN ERR = ERR + DX:Y1 = Y1 + SY
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230 NEXT WHILE
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