testing vector magnitude calculation

magnitest.p8

@@ -0,0 +1,96 @@
+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