# Talk:Field of Vision

(Difference between revisions)

Anyone cares to clarify what is the difference between Field of Vision and Line of Sight??? --Slash 18:08, 8 Apr 2006 (CEST)

As I understand it, field of vision is an algorithm for determining everything is visible. Line of sight is about determining whether a particular square is visible. The former can be created with the latter, but it may be inefficient to do it that way. Duerig 20:44, 23 Apr 2007 (CEST)

## Simple and accurate LOS function

'// Code is [http://www.Blitzbasic.com BlitzMax]

Function UpdateLOS(m:tMonster, UpdateMap:Int = True)
If m = Null Then RuntimeError("Null in LOScheck!")
Local XX:Int, YY:Int '// Clear LOS flag from previous //
For xx = 0 To MAPWIDTH - 1
For yy = 0 To MAPHEIGHT - 1
If Map[xx, yy].InLOS = True Then
Map[xx, yy].HasSeen = True '// HasSeen cells are marked dark
Map[xx, yy].InLOS = False
EndIf
Next
Next

For Local angle:Float = 1 To 360 Step 0.18	'// fractional amount gives better resolution [0.1 causes sight though doors, > 0.2 creates gaps. 0.18 seems the sweet spot
Local dist:Int = 0
Local x:Float = Float(m.X) + 0.5 '//M.x and M.y are player/monster current map location
Local y:Float = Float(m.y) + 0.5
Local xmove:Float = Cos(angle)
Local ymove:Float = Sin(angle)

Repeat
x = x + xmove
y = y + ymove
dist = dist + 1
If dist >= m.Vision Then Exit  '// M.vision is the range of sight
If X >= MAPWIDTH Then Exit
If y >= MAPHEIGHT Then Exit
If x < 0 Then Exit
If y < 0 Then Exit
Map[x, y].InLOS = True
If Map[x, y].BlockVision Then Exit '// Map[,].Blockvision is for walls/closed doors ect
Forever
Next

End Function