pico-8 cartridge // http://www.pico-8.com
version 42
__lua__
--magnitest.p8
--accuracy and perf tests for
--vector calculation logic

-- profiler says 67 cycles
-- 39 lua, 28 system
function bbs28999alg(dx, dy)
  local d = max(abs(dx),abs(dy))
  local n = min(abs(dx),abs(dy)) / d
  return sqrt(n*n + 1) * d
end

-- profiler says 56 cycles
-- 24 lua, 32 system
function bbs28999algopt(dx, dy)
  local d,n=abs(dx),abs(dy)
  if (d<n) d,n=n,d
  n/=d
  return (n*n + 1)^0.5 * d
end

-- profiler says 18 cycles
-- 18 lua, 0 system
function trigalg(dx, dy)
 local s = sin(atan2(dx,dy))
 if (s==0) return abs(dx)
 return abs(dy/s)
end
-->8
function _init()
 gdx,gdy=0,0
 acc=1
 magnitude = 1
 tresult=0
 bresult=0
 delta=0
end

function _update60()
 if (btn(0)) gdx -= acc
 if (btn(1)) gdx += acc
 if (btn(2)) gdy -= acc
 if (btn(3)) gdy += acc
 if (btn(4) and btn(5)) gdx,gdy=0,0

 if btn == 0 or btn(4) then
  acc = 1
 elseif btn(5) then
  acc *= 1.1
 else
  acc *= 1.02
 end

 local a,b=abs(gdx),abs(gdy)
 if (b>a) a,b=b,a
 magnitude = 1
 while magnitude < a do
  magnitude *= 2
 end

 bresult=bbs28999algopt(gdx,gdy)
 tresult=trigalg(gdx,gdy)
 delta=tresult-bresult
end

cols = {
 6,7,
 [4]=10,
 [8]=9,
 [16]=4,
 [32]=14,
 [64]=15,
 [128]=11,
 [256]=12,
 [512]=13,
 [1024]=8,
}

function _draw()
 camera(-63,-63)
 line(0,0,gdx/magnitude,gdy/magnitude,cols[magnitude] or 2)
 rectfill(0,0,gdx/magnitude,0,5)
 rectfill(0,0,0,gdy/magnitude,5)
 print("x: "..tostr(gdx).."  y: "..tostr(gdy).."\nbase: "..tostr(bresult).."\ntrig: "..tostr(tresult).."\n\ndiff: "..tostr(delta),-63,-63)
end

__gfx__
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00700700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00077000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00077000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00700700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000