A quick test to figure out line of sight in 2d array maps.

LineOfSight.as

import flash.geom.Point;

				//0 1 2 3 4
var map:Array = [["#","#","#","#","#"],//0
				 ["#"," "," "," ","#"],//1
				 ["#"," "," "," ","#"],//2
				 ["#","#","#","#","#"],//3
				 ["#"," ","#","#","#"]];//4	

				//0 1 2 3 4
var visibleMap:Array = [["?","?","?","?","?"],
						 ["?","?","?","?","?"],
						 ["?","?","?","?","?"],
						 ["?","?","?","?","?"],
						 ["?","?","?","?","?"]];	


applyLight(map, new Point(4,2));
		   
function applyLight(map:Array, center:Point):void
{
	map[center.x][center.y] = "@";
	var totalRows:int = map[0].length;
	var totalColumns:int = map.length;
	var i:int;
	
	// Get top
	for (i = 0; i < totalColumns; i++)
	{
		raytrace(center.x, center.y, 0, i);
		raytrace(center.x, center.y, totalRows-1, i);
	}
	
	for (i = 0; i < totalRows; i++)
	{
		raytrace(center.x, center.y, i, 0);
		raytrace(center.x, center.y, i, totalColumns-1);
	}
	
	trace(mapToString(map));
	trace(mapToString(visibleMap));
}



function raytrace(x0:int, y0:int, x1:int, y1:int):void
{
    trace(x1,y1);
	var dx:int = Math.abs(x1 - x0);
    var dy:int = Math.abs(y1 - y0);
    var x:int = x0;
    var y:int = y0;
    var n:int = 1 + dx + dy;
    var x_inc:int = (x1 > x0) ? 1 : -1;
    var y_inc:int = (y1 > y0) ? 1 : -1;
    var error:int = dx - dy;
    dx *= 2;
    dy *= 2;
	var hitWall:Boolean = false;
    for (; n > 0; --n)
    {
        var isWall:Boolean = visit(x, y);
		if(isWall)
			n=0;
				
        if (error > 0)
        {
            x += x_inc;
            error -= dy;
        }
        else
        {
            y += y_inc;
            error += dx;
        }
    }
	
}

function visit(x:int, y:int):Boolean{
	var tile:String = map[x][y];
	visibleMap[x][y] = tile;
	return tile == "#" ? true : false;
}

function mapToString(map:Array) : String
{
	var stringMap : String = "";
	var total : int = map.length;
	var i : int;
	// Render Map
	for (i = 0;i < total;i ++)
	{
		stringMap = stringMap + (map[i] as Array).join() + "\n";
	}

	return stringMap;
}