Nav Modifier Volume

Alright – it's time to look at how we can start modifying the Nav Mesh. For instance, there might be a part of the Nav Mesh that we don't want to be crossable, or another section that we want to have different properties. We can do this by using a Nav Modifier Volume.

You can find this setting by going to the Mode panel, under the Volumes tab, and then by going to the Nav Mesh Bounds Volume:

Once this volume has been placed in the map, the default value is to remove the part of the Nav Mesh within the volume, as shown in the following screenshot:

This is useful when you have areas that you don't want your AI to go in, or fix up artifacts of your navigation mesh. Although the Nav Modifier Volume specifies a part of the map, the behavior is specified in the Nav Mesh Areas. This means that, if we look at the settings of the Nav Mesh Modifier Volume, we can find only one related to the Navigation, named Area Class:

As a result, this volume can only specify a portion of the map in which a specific Area Class is applied. By default, the Area Class is NavArea_Null, which "removes" the Nav Mesh in that portion of the map that's overlapping this volume. We'll explore how Nav Mesh Areas work in the next section.