Class RecastGraph Extends NavmeshBase, IUpdatableGraph

Public

Automatically generates navmesh graphs based on world geometry.

The recast graph is based on Recast (http://code.google.com/p/recastnavigation/).
I have translated a good portion of it to C# to run it natively in Unity.

For a tutorial on how to configure a recast graph, take a look at Automatically generating a navmesh.

How a recast graph works

When generating a recast graph what happens is that the world is voxelized. You can think of this as constructing an approximation of the world out of lots of boxes. If you have played Minecraft it looks very similar (but with smaller boxes).

The Recast process is described as follows:

  • The voxel mold is build from the input triangle mesh by rasterizing the triangles into a multi-layer heightfield. Some simple filters are then applied to the mold to prune out locations where the character would not be able to move.

  • The walkable areas described by the mold are divided into simple overlayed 2D regions. The resulting regions have only one non-overlapping contour, which simplifies the final step of the process tremendously.

  • The navigation polygons are peeled off from the regions by first tracing the boundaries and then simplifying them. The resulting polygons are finally converted to triangles which makes them perfect for pathfinding and spatial reasoning about the level.

The recast generation process usually works directly on the visiable geometry in the world. This is usually a good thing, because world geometry is usually more detailed than the colliders. You can, however, specify that colliders should be rasterized instead. If you have very detailed world geometry, this can speed up scanning and updating the graph.

Exporting for manual editing

In the editor there is a button for exporting the generated graph to a .obj file. Usually the generation process is good enough for the game directly, but in some cases you might want to edit some minor details. So you can export the graph to a .obj file, open it in your favourite 3D application, edit it, and export it to a mesh which Unity can import. You can then use that mesh in a navmesh graph.

Since many 3D modelling programs use different axis systems (unity uses X=right, Y=up, Z=forward), it can be a bit tricky to get the rotation and scaling right. For blender for example, what you have to do is to first import the mesh using the .obj importer. Don't change anything related to axes in the settings. Then select the mesh, open the transform tab (usually the thin toolbar to the right of the 3D view) and set Scale -> Z to -1. If you transform it using the S (scale) hotkey, it seems to set both Z and Y to -1 for some reason. Then make the edits you need and export it as an .obj file to somewhere in the Unity project. But this time, edit the setting named "Forward" to "Z forward" (not -Z as it is per default).

A* Pro Feature:

This is an A* Pathfinding Project Pro feature only. This function/class/variable might not exist in the Free version of the A* Pathfinding Project or the functionality might be limited.
The Pro version can be bought here

Inner Types

Public Methods

CalculateTransform ()

Returns a new transform which transforms graph space to world space.

Public
EnsureInitialized ()

Initialize the graph with empty tiles if it is not currently scanned.

Public
IsInsideBounds (point)

True if the point is inside the bounding box of this graph.

Public
ReplaceTiles (tileMeshes, yOffset=0)

Load tiles from a TileMeshes object into this graph.

Public
Resize (newTileBounds)

Resize the number of tiles that this graph contains.

Public
SnapForceBoundsToScene ()

Changes the bounds of the graph to precisely encapsulate all objects in the scene that can be included in the scanning process based on the settings.

Public
TranslateInDirection (dx, dz)

Moves the recast graph by a number of tiles, discarding old tiles and scanning new ones.

Public

Public Static Methods

CalculateTransform (bounds, rotation)
Public Static

Public Variables

MaxTileConnectionEdgeDistance
Public
NavmeshCuttingCharacterRadius
RecalculateNormals
Public
TileWorldSizeX
Public
TileWorldSizeZ
Public
backgroundTraversability

Whether the base of the graph should default to being walkable or unwalkable.

Public
bounds

World bounding box for the graph.

Public
cellSize

Voxel sample size (x,z).

Public
characterRadius

Radius of the agent which will traverse the navmesh.

Public
colliderRasterizeDetail

Controls detail on rasterization of sphere and capsule colliders.

Public
contourMaxError

Max distance from simplified edge to real edge.

Public
dimensionMode

Whether to use 3D or 2D mode.

Public
editorTileSize

Size in voxels of a single tile.

Public
forcedBoundsCenter

Center of the bounding box.

Public
mask

Layer mask which filters which objects to include.

Public
maxEdgeLength

Longer edges will be subdivided.

Public
maxSlope

Max slope in degrees the character can traverse.

Public
meshesUnreadableAtRuntime

Internal field used to warn users when the mesh includes meshes that are not readable at runtime.

Public
minRegionSize

Minumum region size.

Public
rasterizeColliders

Use colliders to calculate the navmesh.

Public
rasterizeMeshes

Use scene meshes to calculate the navmesh.

Public
rasterizeTerrain

Use terrains to calculate the navmesh.

Public
rasterizeTrees

Rasterize tree colliders on terrains.

Public
relevantGraphSurfaceMode

Require every region to have a RelevantGraphSurface component inside it.

Public
rotation

Rotation of the graph in degrees.

Public
scanEmptyGraph

If true, scanning the graph will yield a completely empty graph.

Public
tagMask

Objects tagged with any of these tags will be rasterized.

Public
terrainSampleSize

Controls how large the sample size for the terrain is.

Public
tileSizeX

Size of a tile along the X axis in voxels.

Public
tileSizeZ

Size of a tile along the Z axis in voxels.

Public
useTiles

If true, divide the graph into tiles, otherwise use a single tile covering the whole graph.

Public
walkableClimb

Height the character can climb.

Public
walkableHeight

Character height.

Public

Public Enums

BackgroundTraversability

Whether the base of the graph should default to being walkable or unwalkable.

Public
DimensionMode

Whether to use 3D or 2D mode.

Public
RelevantGraphSurfaceMode
Public

Inherited Public Members

CountNodes ()

Number of nodes in the graph.

Public
EndBatchTileUpdate ()

End batch updating of tiles.

Public
GetNearest (position, constraint=null)

Returns the nearest node to a position using the specified NNConstraint.

Public
GetNearest (position, constraint, maxDistanceSqr)

Nearest node to a position using the specified NNConstraint.

Public
GetNodes (action)

Calls a delegate with all nodes in the graph until the delegate returns false.

Public
GetNodes (action)

Calls a delegate with all nodes in the graph.

Public
GetTile (x, z)

Tile at the specified x, z coordinate pair.

Public
GetTileBounds (rect)

Returns a bounds object with the bounding box of a group of tiles.

Public
GetTileBounds (x, z, width=1, depth=1)

Returns a bounds object with the bounding box of a group of tiles.

Public
GetTileBoundsInGraphSpace (rect)
Public
GetTileBoundsInGraphSpace (x, z, width=1, depth=1)

Returns an XZ bounds object with the bounds of a group of tiles in graph space.

Public
GetTileCoordinates (tileIndex, x, z)

Tile coordinates from a tile index.

Public
GetTileCoordinates (position)

Returns the tile coordinate which contains the specified position.

Public
GetTileIndex (index)

Tile index from a vertex index.

Public Static
GetTiles ()

All tiles.

Public
GetTouchingTiles (bounds, margin=0)

Returns a rect containing the indices of all tiles touching the specified bounds.

Public
GetTouchingTilesInGraphSpace (rect)

Returns a rect containing the indices of all tiles touching the specified bounds.

Public
GetTouchingTilesRound (bounds)

Returns a rect containing the indices of all tiles by rounding the specified bounds to tile borders.

Public
GetVertex (index)

Vertex coordinate for the specified vertex index.

Public
GetVertexArrayIndex (index)
Public
GetVertexInGraphSpace (index)

Vertex coordinate in graph space for the specified vertex index.

Public
Linecast (start, end)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (start, end, hint, hit)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (start, end, hint)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (start, end, hint, hit, trace)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (start, end, hit, trace, filter)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (start, end, hint, hit, trace, filter)

Returns if there is an obstacle between start and end on the graph.

Public
Linecast (graph, start, end, hint, hit)

Returns if there is an obstacle between start and end on the graph.

Public Static
Linecast (graph, origin, end, hint, hit, trace, filter=null)

Returns if there is an obstacle between origin and end on the graph.

Public Static
NearestNodeDistanceSqrLowerBound (position, constraint)

Lower bound on the squared distance from the given point to the closest node in this graph.

Public
OnDrawGizmos (gizmos, drawNodes, redrawScope)

Draw gizmos for the graph.

Public
OnRecalculatedTiles

Called when tiles have been completely recalculated.

Public
PointOnNavmesh (position, constraint)

Finds the first node which contains position.

Public
RelocateNodes (deltaMatrix)

Moves the nodes in this graph.

Public
RelocateNodes (newTransform)

Moves the nodes in this graph.

Public
ReplaceTile (x, z, verts, tris)

Replace tile at index with nodes created from specified navmesh.

Public
Scan ()

Scan the graph.

Public
Snapshot (bounds)

Captures a snapshot of a part of the graph, to allow restoring it later.

Public
StartBatchTileUpdate ()

Start batch updating of tiles.

Public
TileIndexMask
Public Static
TileIndexOffset
Public Static
VertexIndexMask
Public Static
active

Reference to the AstarPath object in the scene.

Public
bounds

World bounding box for the graph.

Public
drawGizmos

Enable to draw gizmos in the Unity scene view.

Public
enableNavmeshCutting

Should navmesh cuts affect this graph.

Public
forcedBoundsSize

Size of the bounding box.

Public
graphIndex

Index of the graph, used for identification purposes.

Public
guid

Used as an ID of the graph, considered to be unique.

Public
infoScreenOpen

Used in the editor to check if the info screen is open.

Public
initialPenalty

Default penalty to apply to all nodes.

Public
isScanned
Public
name

Name of the graph.

Public
navmeshUpdateData

Handles navmesh cutting.

open

Is the graph open in the editor.

Public
persistent

True if the graph will be included when serializing graph data.

Public
showInInspector

True if the graph should be visible in the editor.

Public
showMeshOutline

Show an outline of the polygons in the Unity Editor.

Public
showMeshSurface

Show the surface of the navmesh.

Public
showNodeConnections

Show the connections between the polygons in the Unity Editor.

Public
tileXCount

Number of tiles along the X-axis.

Public
tileZCount

Number of tiles along the Z-axis.

Public
transform

Determines how the graph transforms graph space to world space.

Public

Private/Protected Members

AllocateTilesArray (info)
Private
AssertSafeToUpdateGraph ()

Throws an exception if it is not safe to update internal graph data right now.

Protected
CharacterRadiusInVoxels

Convert character radius to a number of voxels.

Internal
ClearTile (x, z)

Clear the tile at the specified coordinate.

Protected
ConnectTileWithNeighbours (tile, onlyUnflagged=…)
Protected
ConnectTiles (tile1, tile2, tileWorldSizeX, tileWorldSizeZ, maxTileConnectionEdgeDistance)

Generate connections between the two tiles.

Internal Static
CreateNodeConnections (nodes, keepExistingConnections)

Create connections between all nodes.

Protected Static
CreateNodes (tile, tris, tileIndex, graphIndex, tags, initializeNodes, astar, initialPenalty, recalculateNormals)
Internal Static
DeserializeExtraInfo (ctx)

Deserializes graph type specific node data.

Protected
DestroyAllNodes ()

Destroys all nodes in the graph.

Protected
DirtyBounds (bounds)

Notifies the system that changes have been made inside these bounds.

Protected
DisposeUnmanagedData ()

Cleans up any unmanaged data that the graph has.

Protected
DrawUnwalkableNodes (gizmos, size, redrawScope)
Protected
FillWithEmptyTiles ()

Fills graph with tiles created by NewEmptyTile.

Protected
NewEmptyTile (x, z)

Creates a single new empty tile.

Protected
OnDestroy ()

Function for cleaning up references.

Protected
PostDeserialization (ctx)

Called after all deserialization has been done for all graphs.

Protected
ScanInternal (async)

Internal method to scan the graph.

Protected
ScheduleGraphUpdates (graphUpdates)

Schedules a number of graph updates.

Private
SerializeExtraInfo (ctx)

Serializes Node Info.

Protected
TileBorderSizeInVoxels

Number of extra voxels on each side of a tile to ensure accurate navmeshes near the tile border.

Internal
TileBorderSizeInWorldUnits
Internal
exists

True if the graph exists, false if it has been destroyed.

Internal
pendingGraphUpdateArena
Private
tiles

All tiles.

Protected