Custom Navmesh Generation

Reasons to customize the generation or baking of Quantum navmeshes are for example:

  • To generate more accuracy to enable agents for properly walk on a 3D navmesh.
  • To generate a navmesh dynamically during run-time (warning: SDK still has parts of the toolchain that are not deterministic, please contact us).

This section will give an overview how to extend the navmesh tools.

Generating BakeData

The recommended process is to generate the intermediate navmesh format MapNavMesh.BakeData and run this through MapNavMeshBaker.BakeNavMesh(MapData data, MapNavMesh.BakeData navmeshBakeData) which uses the triangle information from the BakeData to fill out all required data structures of a Quantum navmesh.

MapNavMeshBaker.BakeNavMesh() was developed to be used during edit time and replacing it entirely could yield performance improvements, but also would be a much more elaborate task.

MapNavMesh.BakeData Class

StringNameThe name of the navmesh accessible inside the simulation by f.Map.NavMeshes[name]
Vector3PositionThe position of the navmesh. Final navmesh vertices are stored in global space and their positions are translated by this during baking.
FPAgentRadiusThe radius of the largest agents that the navmesh is created for. Older versions of Quantum were permitting different agent radii, but that has been abolished. Now, agents can walk up until their pivot is on the edge of the navmesh. This way the margin agents should keep away from walls is baked into the triangles. This value is only used to render debug graphics.
List<string>Regions All regions ids that are used in this navmesh. During baking the region ids will be added to the Region list of the Map asset and their index is baked into the navmesh triangles region mask (NavMeshTriangle.Regions). The regions are aggregated on the map because a map can have multiple navmeshes that share the region ids.
MapNavMeshVertex[]VerticesThe vertices of the navmesh.
MapNavMeshTriangle[]TrianglesThe triangle of the navmesh. This is a regular mesh data structure where the triangles and vertices are kept in two separate arrays and the triangle points into the vertex array to mark their 3 vertices.
MapNavMeshLink[]LinksLink between positions on the same navmesh.
enumClosestTriangleCalculationThe Quantum navmesh uses a grid for spatial partitioning. Each grid cell will have a fallback triangle assigned. The default search is quite slow (BruteForce) while SpiralOut more efficient is but it could result in empty fallback triangles.
intClosestTriangleCalculationDepthThe number of grid cells to expand the SpiralOut search.
boolEnableQuantum_XYWhen enabled the navmesh baking will flip Y and Z components of the vertex positions to support navmeshes generated in the XY plane.
boolLinkErrorCorrectionAutomatically correct navmesh link positions to the closest triangle during baking.

MapNavMeshTriangle Class

Triangles are expected to have clock-wise winding order. Not all fields have to be filled out. Some of them are only needed for the legacy navmesh drawing tool.

StringIdNot required
String[]VertexIdsMust have length of 3. The referenced vertices as ids. Required for SDK 2.1. or earlier.
Int32[]VertexIds2Must have length of 3. The referenced vertices as indices into the vertex array. Required for SDK 2.2.
Int32AreaNot required
StringRegionIdThe region that this triangle belongs to. Default is null.
FPCosthe cost of the triangle. Default should be FP._1.

MapNavMeshVertex Class

The types of Position has been replaced by FPVector3 SDK 2.2.

StringIdRequired for SDK 2.1 or earlier
Vector3PositionThe position of the vertex
List<Int32>NeighborsNot required
List<Int32>TrianglesNot required

MapNavMeshLink Class

The types of Start, End and CostOveride have been replaced by FPVector3 and FP respectively in SDK 2.2.

Vector3StartStart position of the link. Must be on the same navmesh.
Vector3EndEnd position of the link. Must be on the same navmesh.
boolBidirectionalCan the link be traversed from both directions.
floatCostOverrideThe cost of the connection.
StringRegionIdThe region id that the link belongs to. Default is null.
StringNameThe name of the link. Can be queried by navmesh.Links[NavMeshPathfinder.CurrentLink()].Name.


// Generate simple navmesh BakeData
var bakeData = new MapNavMesh.BakeData() {
  AgentRadius = FP._0_20,
  ClosestTriangleCalculation = MapNavMesh.FindClosestTriangleCalculation.SpiralOut,
  ClosestTriangleCalculationDepth = 1,
  Name = "DynamicNavmesh",
  PositionFP = FPVector3.Zero,
  Regions = new System.Collections.Generic.List<string>(),
  Vertices = new MapNavMeshVertexFP[] {
    new MapNavMeshVertexFP { Position = FPVector3.Forward },
    new MapNavMeshVertexFP { Position = FPVector3.Right },
    new MapNavMeshVertexFP { Position = -FPVector3.Forward},
    new MapNavMeshVertexFP { Position = -FPVector3.Right},
  Triangles = new MapNavMeshTriangle[] {
    new MapNavMeshTriangle { VertexIds2 = new int[] { 0, 1, 2}, Cost = FP._1 },
    new MapNavMeshTriangle { VertexIds2 = new int[] { 0, 2, 3}, Cost = FP._1 }

Replacing Navmesh Assets Before Starting The Simulation

Replacing the content of an existing Unity Quantum navmesh asset before starting the simulation. All clients and late-joiners have to perform this.


  • navmesh-deterministic-baking branch for SDK 2.1 (please contact us)
  • The BakeData generation is deterministic

Replacing the asset must be done before the navmesh is loaded through the UnityDB and before the simulation has started. In this snippet the Unity navmesh asset is loaded to replace the Quantum asset inside it (.Settings) and the Guid and Path values are copied. Invalidating the .DataAsset will prevent the deserialization of the binary navmesh asset (_data asset) when it is finally loaded by Quantum.

var navmesh = MapNavMeshBaker.BakeNavMesh(mapdata.Asset.Settings, bakeData, null);
var navmeshAsset = UnityEngine.Resources.Load<NavMeshAsset>("PathToNavmeshAsset");
navmesh.Guid = navmeshAsset.Settings.Guid;
navmesh.Path = navmeshAsset.Settings.Path;
navmeshAsset.Settings = navmesh;
navmeshAsset.Settings.DataAsset.Id = AssetGuid.Invalid;

// QuantumRunner.StartGame()

Injecting Navmeshes During Runtime

Restrictions By The Map Asset

The Map asset carries two look up for convenient navmesh and Region name lookups that are populated when the map and associated navmeshes is loaded. Both lookups will not work with dynamic navmesh assets.

public Dictionary<String, NavMesh> NavMeshes;
public Dictionary<String, Int32> RegionMap;
public NavMesh GetNavMesh(String name) {}

GetNavMesh() Alternative

The navmesh lookup in Map (f.Map.GetNavMesh(name)) cannot be used for dynamic navmeshes because modifying the dictionary on Map does not work for late-joiner or reconnecting players. Instead use this snippet to search for all navmeshes:

public static NavMesh FindNavmeshByName(Frame f, string name) {
  var result = f.Map.GetNavMesh(name);
  if (result != null) {
    return result;

  foreach (var a in f.DynamicAssetDB.Assets) {
    if (a is NavMesh navmeshAsset) {
      if (navmeshAsset.Name == name) {
        return navmeshAsset;

  return null;

Alternatively create and manage a navmesh lookup saved on f.Globals:

global {
  dictionary<QStringUtf8<32>, asset_ref<NavMesh>> Navmeshes;

Using Regions On Dynamic Navmeshes

If a dynamic navmesh has regions itself it has to reuse all regions loaded by the static map and other dynamic regions. If it has new regions they are not allowed to use the same regions ids already used. Toggling would not work properly.

Best to create one static RegionMap offline and use it inside dynamic generated navmeshes. The RegionMap is created during Map.Loaded() from the maps Region member.

public string[] Regions;

Injecting Navmeshes Inside The Simulation

Deterministically create NavmeshBakeData and bake a Quantum navmesh inside the simulation during runtime. Uses Quantum dynamic database.


  • navmesh-deterministic-baking branch for SDK 2.1 (please contact us)
  • NavmeshBakeData creation needs to be deterministic
  • Must be performed during a verified frame

The navmesh baking code has been moved (copied in 2.1) to the quantum.code project to be able to run outside Unity.

using Quantum.Experimental;

// May be more buffer required for serialization
private static byte[] _byteStreamData = new byte[1024 * 1024];

// Generate bake data
var bakeData = new NavmeshBakeData() {
  AgentRadius = FP._0_20,
  ClosestTriangleCalculation = NavMeshBakeDataFindClosestTriangle.SpiralOut,
  ClosestTriangleCalculationDepth = 1,
  Name = "DynamicNavmesh",
  PositionFP = FPVector3.Zero,
  Regions = new List<string>(),
  Vertices = new Experimental.NavmeshBakeDataVertex[] {
    new NavmeshBakeDataVertex { Position = FPVector3.Forward },
    new NavmeshBakeDataVertex  { Position = FPVector3.Right },
    new NavmeshBakeDataVertex  { Position = -FPVector3.Forward},
    new NavmeshBakeDataVertex  { Position = -FPVector3.Right},
  Triangles = new NavmeshBakeDataTriangle[] {
    new NavmeshBakeDataTriangle { VertexIds = new int[] { 0, 1, 2}, Cost = FP._1 },
    new NavmeshBakeDataTriangle { VertexIds = new int[] { 0, 2, 3}, Cost = FP._1 }

// Bake navmesh asset
var navmesh = NavmeshBaker.BakeNavMesh(f.Map, bakeData);

// Create and add binary navmesh data asset (to support late joiners)
var byteStream = new ByteStream(_byteStreamData);
navmesh.Serialize(byteStream, true);
var binaryDataAsset = new BinaryData();
binaryDataAsset.Data = byteStream.ToArray();
var binaryDataAssetRef = new AssetRefBinaryData();
binaryDataAssetRef.Id = f.AddAsset(binaryDataAsset);
navmesh.DataAsset = binaryDataAssetRef;

// Add navmesh to Dynamic DB

Also use the FindNavmeshByName() snippet from the next section to correctly find dynamic navmesh assets by name.

Injecting Navmeshes From Unity

Works for late-joiners. Must be initiated by one client.


Create BakeData in Unity on one client and use the AssetInjection command:

var map = QuantumRunner.Default.Game.Frames.Verified.Map;
// Bake navmesh
var navmesh = MapNavMeshBaker.BakeNavMesh(map, bakeData, null);
var data = AssetInjectionUtility.SerializeAsset(null, navmesh);
// Adjust PlayerRef 0
AssetInjectionUtility.InjectAsset(QuantumRunner.Default.Game, 0, bakeData.Name, data);

To render the gizmos of the dynamic navmesh change the following line in QuantumGameGizmos.cs:

// ################## NavMeshes ##################

if (editorSettings.DrawNavMesh) {
  var listOfNavmeshes = new System.Collections.Generic.List<NavMesh>();
  if (editorSettings.DrawNavMesh) {
  if (frame.DynamicAssetDB.IsEmpty == false) {
     listOfNavmeshes.AddRange(frame.DynamicAssetDB.Assets.Where(a => a is NavMesh).Select(a => (NavMesh)a).ToList());
  foreach (var navmesh in listOfNavmeshes) {
    // ...

To Document Top