collect_location.lua

   1 QuestHelper_File["collect_location.lua"] = "Development Version"
   2 QuestHelper_Loadtime["collect_location.lua"] = GetTime()
   3
   4 -- little endian two's complement
   5 local function signed(c)
   6   QuestHelper: Assert(not c or c >= -127 and c < 127)
   7   if not c then c = -128 end
   8   if c < 0 then c = c + 256 end
   9   return strchar(c)
  10 end
  11
  12 local function float(c)
  13   if c then
  14     c = math.floor(c * 1000 + 0.5) -- get our 3 digits, then integer it
  15     QuestHelper: Assert(c >= -2147483647 and c < 2147483647)
  16   else
  17     c = -2147483648
  18   end
  19   if c < 0 then c = c + 4294967296 end
  20   return strchar(bit.band(c, 0xff), bit.band(c, 0xff00) / 256, bit.band(c, 0xff0000) / 65536, bit.band(c, 0xff000000) / 16777216)
  21 end
  22
  23 local function BolusizeLocation(c, x, y, rc, rz)
  24   -- c, rc, and rz are all *signed* integers that fit within an 8-bit int.
  25   -- x and y are floating-point values. We're going to assume they're 5-digit, but we also want at least 3 digits of precision. (Note that 3 digits is a more than most sites use - most of them do 3 digits in terms of local map coordinates, but most maps are more than 1000 yards large, with the exception of some major cities.) That's 8 digits total, so we're gonna be spending 32 bits on this. Lua uses 64-bit float types, which have something like 53 digits of precision, so we've got plenty of accuracy for our 32 bits.
  26   -- Overall we're using a somewhat-weird 11 bytes on this. Meh.
  27   -- Also, any nil values are being turned into MIN_WHATEVER.
  28   return signed(c) .. float(x) .. float(y) .. signed(rc) .. signed(rz)
  29 end
  30
  31 -- This merely provides another API function
  32 function QH_Collect_Location_Init(_, API)
  33   API.Callback_LocationBolus = BolusizeLocation  -- Yeah. *Bolusize*. You heard me.
  34   API.Callback_LocationBolusCurrent = function () return BolusizeLocation(API.Callback_RawLocation()) end  -- This is just a convenience function, really
  35 end