While working on my 3d engine I've written a function that I think would be generally useful and I haven't seen it done before. It draws horizontal dithered lines such that odd and even rows have an alternating checkerboard pattern. Code is obviously in the cart but I post below as well.
The code runs just as fast the native LINE function but with the bonus of optional dithered-e-ness
function dither(sx,ex,y,draw_colour,shade_colour) if (sx<0 and ex<0) or (sx>127 and ex>127) then return end sx = max(0,min(sx,127)) ex = max(0,min(ex,127)) if ex < sx then sx,ex = ex,sx end local sos = sx % 2 local eos = ex % 2 local yind = y*64+0x6000 local ctu = -1 if y%2 == 0 then ctu = draw_colour else ctu = shade_colour end if sos == 1 then sx -= 1 poke(yind+sx/2, bor(band(peek(yind+sx/2),0x0f), band(0xf0,ctu))) sx += 2 end if eos == 0 then poke(yind+flr(ex/2), bor(band(peek(yind+ex/2),0xf0),band(0x0f, ctu))) ex -= 1 end memset(yind +sx/2,ctu, (ex/2-sx/2)+1) end
The tricky bit being to deal with the start and end of the line when they do no perfectly align with the byte boundaries.
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