Navigation Mesh

Owned by Manuel Matscher
Last updated: Sept 21, 2021
2 min read
navmesh on intersection

The navigation mesh is important for the pedestrian navigation through your map and the spawning of passengers at your bus stops.

The test map already has a basic navmesh setup, if you enable the navmesh visibility in the show flags or press P you should be able to see the navmesh.

Red Areas: These areas mark streets, pedestrians will avoid this area wherever possible, they will walk across this area to board buses and to J-walk if they can’t find any crosswalks in the vicinity

navmesh at bus stop

Blueish Purple Areas: These marks walking areas. Pedestrians will spawn and walk here

Turquoise Areas: These mark transition areas between streets and walkways, this prevents pedestrians form walking to close to the street

Blue Areas: These mark crosswalks

Purple Areas: These mark passenger spawn areas in front of bus stops. If there is no purple area in front of a stop, passengers will not spawn

Black Areas: No navmesh area. Neither Pedestrians nor passengers will walk or spawn here.

Navmesh Bounds

The navmesh bounds define the area in which the navmesh will be created. They are defined by the NavMeshBoundsVolume assets. We recommend to setup multiple smaller navmesh volumes focused on walkable areas than one big volume over your whole map. Both setups will work one bit volume will significantly increase the memory foot print of your map for no real gain, as most of the additional navmesh area will not be accessible by NPCs.

The navmesh on the streets will be automatically generated with the correct navmesh areas, but we need to manually change the size of the street nav mesh generation if we increase the size of the network significantly.

  1. select the SASRoadNetworkActor

  2. search the New Road Nav Modifier Component section

  3. expand the Bounding Box → Shape section

  4. increase the Box Extents to the needed values, the extents are measured in cm

Navmesh Modifiers

The navmesh will by default only be created for the street, causing pedestrians to only walk on sidewalks. To populate areas like parks we need to add a Navmesh modifier to those areas.

Search for the NavModifierSidwalk blueprint and add it to the scene. Scale it up and move it to the place you want to be walkable for pedestrians

Regenerating NavMesh

In the top bar click the arrow next to build and select Build Paths