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.

Inspector

Shape

Dimensions

Whether to use 3D or 2D mode.

Center

Center of the bounding box.

Size

Size of the bounding box.

Rotation

Rotation of the graph in degrees.

Snap bounds to scene ()

Input Filtering

Filter Objects By

Determines how the initial filtering of objects is done.

Layer Mask

Objects in all of these layers will be rasterized.

Tag Mask

Objects tagged with any of these tags will be rasterized.

Rasterize Terrains

Use terrains to calculate the navmesh.

Rasterize Trees

Rasterize tree colliders on terrains.

Heightmap Downsampling

Controls how much to downsample the terrain's heightmap before generating the input mesh used for rasterization.

Rasterize Meshes

Use scene meshes to calculate the navmesh.

Rasterize Colliders

Use colliders to calculate the navmesh.

Agent Characteristics

Character Radius

Radius of the agent which will traverse the navmesh.

Character Height

Character height.

Max Step Height

Height the character can climb.

Max Slope

Max slope in degrees the character can traverse.

Per Layer Modifications

List of rules that modify the graph based on the layer of the rasterized object.

Rasterization

Voxel Size

Voxel sample size (x,z).

Use Tiles

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

Tile Size

Size in voxels of a single tile.

Max Border Edge Length

Longer edges will be subdivided.

Edge Simplification

Max distance from simplified edge to real edge.

Min Region Size

Minumum region size.

Round Collider Detail

Controls detail on rasterization of sphere and capsule colliders.

Runtime Settings

Affected By Navmesh Cuts

Should navmesh cuts affect this graph.

Advanced

Relevant Graph Surface Mode

Require every region to have a RelevantGraphSurface component inside it.

Initial Penalty

Default penalty to apply to all nodes.

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

Settings for which meshes/colliders and other objects to include in the graph.

Per layer modification settings.

Public Methods

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

IsInsideBounds (point)

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

ReplaceTiles (tileMeshes, yOffset=0)

Load tiles from a TileMeshes object into this graph.

Resize (newTileBounds)

Resize the number of tiles that this graph contains.

Changes the bounds of the graph to precisely encapsulate all objects in the scene.

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

Public Variables

MaxTileConnectionEdgeDistance

Maximum (vertical) distance between the sides of two nodes for them to be connected across a tile edge.

Public
NavmeshCuttingCharacterRadius
RecalculateNormals

Determines how normals are calculated.

Public
TileWorldSizeX

Size of a tile in world units along the X axis.

Public
TileWorldSizeZ

Size of a tile in world units along the Z axis.

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
collectionSettings

Determines which objects are used to build the graph, when it is scanned.

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
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
perLayerModifications

List of rules that modify the graph based on the layer of the rasterized object.

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
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

ClearTiles (tileRect)

Clears the tiles in the specified rectangle.

Number of nodes in the graph.

End batch updating of tiles.

GetNearest (position, [...])

...

GetNodes (action)

Calls a delegate with all nodes in the graph...

GetTile (x, z)

Tile at the specified x, z coordinate pair.

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

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

...

GetTileIndex (index)

Tile index from a vertex index.

All tiles.

GetTouchingTiles (bounds, margin=0)

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

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

GetVertex (index)

Vertex coordinate for the specified vertex index.

Vertex coordinate in graph space for the specified vertex index.

IsPointOnNavmesh (position)

True if the point is on a walkable part of the navmesh, as seen from above.

Linecast (..., end, ...)

Returns if there is an obstacle between...

NearestNodeDistanceSqrLowerBound (position, constraint)

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

OnDrawGizmos (gizmos, drawNodes, redrawScope)

Draw gizmos for the graph.

OnRecalculatedTiles

Called when tiles have been completely recalculated.

Public
PointOnNavmesh (position, constraint)

Finds the first node which contains position.

RandomPointOnSurface (nnConstraint=null, highQuality=true)

A random point on the graph.

Moves the nodes in this graph.

ReplaceTile (x, z, verts, tris, [tags], [tryPreserveExistingTagsAndPenalties])

Replace tile at index with nodes created from specified navmesh.

Scan ()

Scan the graph.

Snapshot (bounds)

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

StartBatchTileUpdate (exclusive=…)

Start batch updating of tiles.

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

True if the graph has been scanned and contains nodes.

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

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

CharacterRadiusInVoxels

Convert character radius to a number of voxels.

Internal
ClearTile (x, z, replacement)

Clear the tile at the specified coordinate.

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

Generate connections between the two tiles.

CreateNodeConnections (nodes, keepExistingConnections)

Create connections between all nodes.

CreateNodes (tile, tris, tileIndex, graphIndex, tags, initializeNodes, astar, initialPenalty, tryPreserveExistingTagsAndPenalties)

Deserializes graph type specific node data.

Destroys all nodes in the graph.

DirtyBounds (bounds)

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

Cleans up any unmanaged data that the graph has.

DrawUnwalkableNodes (gizmos, size, redrawScope)

Fills graph with tiles created by NewEmptyTile.

NewEmptyTile (x, z)

Creates a single new empty tile.

Function for cleaning up references.

Called after all deserialization has been done for all graphs.

ReplaceTilePostCut (x, z, verts, tris, tags, tryPreserveExistingTagsAndPenalties=true, preservePreCutData=…)
ScanInternal ([...])

Internal method to scan the graph.

ScheduleGraphUpdates (graphUpdates)

Schedules a number of graph updates.

Serializes Node Info.

SetLayout (info)
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
hasExtendedInX
Private
hasExtendedInZ
Private
pendingGraphUpdateArena
Private
tiles

All tiles.

Protected

Deprecated Members

colliderRasterizeDetail

Controls detail on rasterization of sphere and capsule colliders.

Public
mask

Layer mask which filters which objects to include.

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
tagMask

Objects tagged with any of these tags will be rasterized.

Public
terrainSampleSize

Controls how large the sample size for the terrain is.

Public