Line of sight

[na_th_an]

There's a much faster distance formula, which doesn't require square roots, albeit it's not as precise, but it works. It's what I use in my games - I can't afford a square root per frame so I just...

Code:

Function distance (x1 as uByte, y1 as uByte, x2 as uByte, y2 as uByte)
   dim dx as uByte
   dim dy as uByte
   dim mn as uByte

   dx = Abs (x2 - x1)
   dy = Abs (y2 - y1)
  
   If dx < dy Then
      mn = dx
   Else
      mn = dy
   End If

   Return (dx + dy - (mn >> 1) - (mn >> 2) + (mn >> 4))
End Function

Roughly translated from C code, but should work:

Code:

unsigned char distance (unsigned char x1, unsigned char y1, unsigned char x2, unsigned char y2) {
    unsigned char dx = abs (x2 - x1);
    unsigned char dy = abs (y2 - y1);
    unsigned char mn = dx < dy ? dx : dy;
    return (dx + dy - (mn >> 1) - (mn >> 2) + (mn >> 4));
}