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roblogic/hacker-logo-glider.bas

Created December 17, 2020 02:41
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Apple II BASIC code for drawing the "hacker logo": a glider from Conway's Game of Life
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hacker-logo-glider.bas
0data51,29,73,51,73,73,51,73,29,73
1hgr2:hcolor=3:fori=0to191:hplot0,i to191,i:hplot i,0toi,191:next
2hcolor=0:fori=18to84step22:hplot18,i to84,i:hplot i,18toi,84:next
3fori=1to5:reada,b:a=a+.5:b=b+.5:gosub4:next:end
4forr=0to9step0.5:r2=r*r:for x=0 to r:y=sqr(r2-x*x)
5hplot a+x,y+b:hplot a-x,y+b:hplot a+x,-y+b:hplot a-x,-y+b
6hplot a+y,x+b:hplot a-y,x+b:hplot a+y,-x+b:hplot a-y,-x+b
7next:next:return
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0data... locates the circles. 1hgr2... draws white background. 2hcolor... draws grid. 3for..read.. gets data & calls the circle subroutine. (.5 is added at various points because of quirky Apple II drawing logic). 4for... to 7..return is a unique algorithm for circles using SQR. (algo adapted from this tutorial).

Verified at https://www.calormen.com/jsbasic/

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