mirror of
https://github.com/inexorabletash/jsbasic.git
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84 lines
1.9 KiB
Plaintext
84 lines
1.9 KiB
Plaintext
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0 REM Sky palette:
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0 REM Clouds 6/1 (light blue)
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0 REM Sky 6/6 (blue)
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0 REM Dusk 6/2 (purple)
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0 REM Night 6/0 (dark blue)
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0 REM Ground palette:
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0 REM Water 6/0 (dark blue)
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0 REM Water (night) 0/0 (black)
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0 REM Water 6/1 (turquoise)
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0 REM Cement 1/2 (gray)
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0 REM Grass 1/1 (green)
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0 REM Forest 1/0 (dark green)
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0 REM Sand 5/1 (khaki)
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0 REM Tundra 1/3 (light green)
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0 REM Ice 3/3 (white)
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10 HGR : HGR2 : PG = 0
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20 DIM SC(192), GC(192)
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30 FOR Y = 0 TO 191 STEP 2
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: SC(Y) = 6 : SC(Y+1) = 6
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: GC(Y) = 5 : GC(Y+1) = 1
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: NEXT
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100 POKE 49236 + (1-PG), 0 : POKE 230, 32 + 32 * PG
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120 M = 2 * ( 0.5 - (PDL(0) / 255) )
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121 B = 192 * (PDL(1) / 255) - 96
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122 B = B * 2
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140 GOSUB 1000
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150 PG = PG + 1 : IF PG > 1 THEN PG = 0
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160 GOTO 100
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999 END
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1000 REM Draw sky/horizon; call w/ M, B (y=Mx + B); 0,0 is center
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1010 Y1 = ( M * -140 ) + B + 96
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1011 Y2 = ( M * 140 ) + B + 96
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1012 IF Y1 < 0 AND Y2 < 0 THEN FOR Y = 0 TO 191
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: HCOLOR= GC(Y) : HPLOT 0,Y TO 279,Y
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: NEXT : RETURN
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1013 IF Y1 > 279 AND Y2 > 279 THEN FOR Y = 0 TO 191
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: HCOLOR= SC(Y) : HPLOT 0,Y TO 279,Y
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: NEXT : RETURN
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1014 IF Y1 = Y2 THEN Y1 = INT(Y1)
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: FOR Y = 0 TO Y1 - 1
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: HCOLOR= SC(Y) : HPLOT 0,Y TO 279,Y
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: NEXT
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: FOR Y = Y1 TO 191
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: HCOLOR= GC(Y) : HPLOT 0,Y TO 279,Y
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: NEXT
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: RETURN
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1015 REM TODO: Optimize for near-horizontal lines with solid above/below
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: REM (y-b)/m = x
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1020 X1 = ( -96 - B ) / M + 140
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1021 X2 = ( 96 - B ) / M + 140
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1022 DX = (X2 - X1) / 192
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: REM TODO: flip colors if DX is negative
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1040 XF = X1 : FOR Y = 0 TO 191 : X = INT(XF) : XF = XF + DX
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1041 IF DX <= 0 THEN C1 = SC(Y) : C2 = GC(Y)
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1042 IF DX > 0 THEN C1 = GC(Y) : C2 = SC(Y)
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1050 IF X < 1 THEN HCOLOR= C2 : HPLOT 0,Y TO 279,Y : GOTO 1080
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1051 IF X > 279 THEN HCOLOR= C1 : HPLOT 0,Y TO 279,Y : GOTO 1080
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1052 HCOLOR= C1 : HPLOT 0,Y TO X-1, Y : HCOLOR= C2 : HPLOT X,Y TO 279,Y
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1080 NEXT : RETURN
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