MapVisual.prototype.recenter = function(me) {

    var gridCoord = this.map.worldCoordsToGridCoords(me.x, me.y)

    if (this.previousX !== gridCoord.x || this.previousY !== gridCoord.y) {

        var dx = gridCoord.x - this.previousX
        var dy = gridCoord.y - this.previousY

        // start
        var sx = gridCoord.x - 14
        var sy = gridCoord.y - 10

        // end
        var ex = gridCoord.x + 14
        var ey = gridCoord.y + 10

        // add floors and walls within the range of start to end (if they aren't in the cache)
        for (var i = sx; i < ex; i++) {
            for (var j = sy; j < ey; j++) {
                var wall = this.map.getWall(i, j)
                var floor = this.map.getFloor(i, j)
                var cacheKey = createKey(i, j)

                if (wall.type !== WallType.Void && wall.type !== WallType.None && typeof this.wallCache[cacheKey] === 'undefined') {
                    var index = indexify(i, j, this.map.walls)
                    var frameName = getWallImageFrameName(wall.type, index)
                    var sprite = new PIXI.Sprite.fromFrame(frameName)
                    sprite.x = i * 16
                    sprite.y = j * 16
                        //sprite.anchor.y = 1/3
                    this.wallLayer.addChild(sprite)
                    this.wallCache[cacheKey] = sprite
                }

                if (floor.type !== FloorType.Void && typeof this.floorCache[cacheKey] === 'undefined') {
                    var index = indexify(i, j, this.map.floors)
                    var frameName = getFloorImageFrameName(floor.type, index)
                    var sprite = new PIXI.Sprite.fromFrame(frameName)
                    sprite.x = i * 16
                    sprite.y = j * 16
                    this.groundLayer.addChild(sprite)
                    this.floorCache[cacheKey] = sprite
                }
            }
        }


        // remove floors and walls that are no longer on screen
        if (dx < 0) {
            var rx = ex - dx
            for (var i = sy; i <= ey; i++) {
                var cacheKey = createKey(rx, i)
                if (typeof this.floorCache[cacheKey] !== 'undefined') {
                    this.groundLayer.removeChild(this.floorCache[cacheKey])
                    delete this.floorCache[cacheKey]
                }
                if (typeof this.wallCache[cacheKey] !== 'undefined') {
                    this.wallLayer.removeChild(this.wallCache[cacheKey])
                    delete this.wallCache[cacheKey]
                }
            }
        }

        if (dx > 0) {
            var rx = sx - dx
            for (var i = sy; i <= ey; i++) {
                var cacheKey = createKey(rx, i)
                if (typeof this.floorCache[cacheKey] !== 'undefined') {
                    this.groundLayer.removeChild(this.floorCache[cacheKey])
                    delete this.floorCache[cacheKey]
                }
                if (typeof this.wallCache[cacheKey] !== 'undefined') {
                    this.wallLayer.removeChild(this.wallCache[cacheKey])
                    delete this.wallCache[cacheKey]
                }
            }
        }

        if (dy < 0) {
            var ry = ey - dy
            for (var i = sx; i <= ex; i++) {
                var cacheKey = createKey(i, ry)
                if (typeof this.floorCache[cacheKey] !== 'undefined') {
                    this.groundLayer.removeChild(this.floorCache[cacheKey])
                    delete this.floorCache[cacheKey]
                }
                if (typeof this.wallCache[cacheKey] !== 'undefined') {
                    this.wallLayer.removeChild(this.wallCache[cacheKey])
                    delete this.wallCache[cacheKey]
                }
            }
        }

        if (dy > 0) {
            var ry = sy - dy
            for (var i = sx; i <= ex; i++) {
                var cacheKey = createKey(i, ry)
                if (typeof this.floorCache[cacheKey] !== 'undefined') {
                    this.groundLayer.removeChild(this.floorCache[cacheKey])
                    delete this.floorCache[cacheKey]
                }
                if (typeof this.wallCache[cacheKey] !== 'undefined') {
                    this.wallLayer.removeChild(this.wallCache[cacheKey])
                    delete this.wallCache[cacheKey]
                }
            }


        }
    }

    this.previousX = gridCoord.x
    this.previousY = gridCoord.y

}