var IsInLayerBounds = require('./IsInLayerBounds'); 
var GetTileAt = function (tileX, tileY, nonNull, layer){ 
if (nonNull === undefined) { 
nonNull = false ; 
} 
if (IsInLayerBounds(tileX, tileY, layer)) { 
var tile = layer.data[tileY][tileX]; 
if (tile === null ) { 
return null ; 
} 
 else if (tile.index === -1) { 
return nonNull? tile: null ; 
} 
 else { 
return tile; 
} 
} 
 else { 
return null ; 
} 
} 
; 
module.exports = GetTileAt;