# Modifiers

## Modifiers

Modifiers are actions which modify a map. TileWorldCreator comes with multiple ready to use modifiers but you can also implement your own.

### Add

Add the output of a layer to this layer

### Subtract

Subtract a layer from this layer

### Expand

Expand the tile borders by one tile

### Shrink

Shrink the tile borders by one tile

### Invert

Invert the map

### Offset

Offset the map result by the offset amount

### Overlap

Outputs only the overlapping tiles of two blueprint layers

### Smooth

Smoothes the map by the smoothness amount.

### PlayerPosition

The PlayerPosition modifier tries to find the best possible place to spawn a player. This is done by subdividing the map in to 9 quadrants and searching for a fill tile in one of these quadrants. The output will be one single tile which can then be used by a object instantiation layer to instantiate the player object.

[![playerPosition](https://github.com/doorfortyfour/TileWorldCreator/raw/master/docs/img/playerPosition.png)](https://github.com/doorfortyfour/TileWorldCreator/blob/master/docs/img/playerPosition.png)

`TopLeft`\
`TopCenter`\
`TopRight`\
`MiddleLeft`\
`MiddleCenter`\
`MiddleRight`\
`BottomLeft`\
`BottomCenter`\
`BottomRight`

### Select

This is probably the most powerful modifier as it let's you select different parts of your map based on the tiles type or based on rules.

> Combining multiple select modifiers can help extract very specific parts of your map.

**Select by rules**

When using the rule type you can define multiple "neighbour" rules. This means that the selection modifier checks for each tile if the rule applies to it this tile.

**Example**\
So for example if you set a rule like this:\
[![ruleSelection](https://github.com/doorfortyfour/TileWorldCreator/raw/master/docs/img/ruleSelection.png)](https://github.com/doorfortyfour/TileWorldCreator/blob/master/docs/img/ruleSelection.png)

This means, only select the tiles which have a neighbour on the left, right, bottom-left, bottom-right and bottom-center.\
So the tile which are orange in the image are being selected now.