AIPath Class Reference

AI for following paths. More...

Detailed Description

AI for following paths.

This AI is the default movement script which comes with the A* Pathfinding Project. It is in no way required by the rest of the system, so feel free to write your own. But I hope this script will make it easier to set up movement for the characters in your game. This script works well for many types of units, but if you need the highest performance (for example if you are moving hundreds of characters) you may want to customize this script or write a custom movement script to be able to optimize it specifically for your game.

This script will try to follow a target transform. At regular intervals, the path to that target will be recalculated. It will in the Update method try to move towards the next point in the path. However it will only move in roughly forward direction (Z+ axis) of the character, but it will rotate around it's Y-axis to make it possible to reach the destination.

Quick overview of the variables

In the inspector in Unity, you will see a bunch of variables. You can view detailed information further down, but here's a quick overview.
The repathRate determines how often it will search for new paths, if you have fast moving targets, you might want to set it to a lower value.
The target variable is where the AI will try to move, it can be a point on the ground where the player has clicked in an RTS for example. Or it can be the player object in a zombie game.
The speed is self-explanatory, so is rotationSpeed, however slowdownDistance might require some explanation. It is the approximate distance from the target where the AI will start to slow down.
pickNextWaypointDist is simply determines within what range it will switch to target the next waypoint in the path.

Below is an image illustrating several variables as well as some internal ones, but which are relevant for understanding how it works.

Note

The image is slightly outdated, replace forwardLook with pickNextWaypointDist in the image and ignore the circle for pickNextWaypointDist.

This script has many movement fallbacks. If it finds an RVOController attached to the same GameObject as this component, it will use that. If it fins a character controller it will also use that. Lastly if will fall back to simply modifying Transform.position which is guaranteed to always work and is also the most performant option.

Public Member Functions
Vector3	CalculateVelocity (Vector3 position)
	Current desired velocity of the agent (excluding physics and local avoidance but it includes gravity).
override void	OnPathComplete (Path newPath)
	Called when a requested path has been calculated.
virtual void	OnTargetReached ()
	The end of the path has been reached.
override void	Teleport (Vector3 newPosition, bool clearPath=true)
	Instantly move the agent to a new position.
Public Member Functions inherited from AIBase
virtual void	FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation)
	Moves the agent to a position.
virtual Vector3	GetFeetPosition ()
	Position of the base of the character.
virtual void	Move (Vector3 deltaPosition)
	Move the agent.
void	MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation)
	Calculate how the character wants to move during this frame.
virtual void	SearchPath ()
	Recalculate the current path.
Quaternion	SimulateRotationTowards (Vector3 direction, float maxDegrees)
	Simulates rotating the agent towards the specified direction and returns the new rotation.
Public Member Functions inherited from IAstarAI
void	FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation)
	Move the agent.
void	Move (Vector3 deltaPosition)
	Move the agent.
void	MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation)
	Calculate how the character wants to move during this frame.
void	SearchPath ()
	Recalculate the current path.
void	Teleport (Vector3 newPosition, bool clearPath=true)
	Instantly move the agent to a new position.

Public Attributes
bool	alwaysDrawGizmos
	Draws detailed gizmos constantly in the scene view instead of only when the agent is selected and settings are being modified.
float	endReachedDistance = 0.2F
	Distance to the end point to consider the end of path to be reached.
float	pickNextWaypointDist = 2
	Determines within what range it will switch to target the next waypoint in the path.
float	rotationSpeed = 360
	Rotation speed.
float	slowdownDistance = 0.6F
	Distance from the target point where the AI will start to slow down.
bool	slowWhenNotFacingTarget = true
	Slow down when not facing the target direction.
CloseToDestinationMode	whenCloseToDestination = CloseToDestinationMode.Stop
	What to do when within endReachedDistance units from the destination.
Public Attributes inherited from AIBase
bool	canMove = true
	Enables or disables movement completely.
bool	canSearch = true
	Enables or disables recalculating the path at regular intervals.
float	centerOffset = 1
	Offset along the Y coordinate for the ground raycast start position.
Vector3	gravity = new Vector3(float.NaN, float.NaN, float.NaN)
	Gravity to use.
LayerMask	groundMask = -1
	Layer mask to use for ground placement.
float	maxSpeed = 1
	Max speed in world units per second.
IMovementPlane	movementPlane = GraphTransform.identityTransform
	Plane which this agent is moving in.
float	repathRate = 0.5f
	Determines how often the agent will search for new paths (in seconds).
bool	rotationIn2D = false
	If true, the forward axis of the character will be along the Y axis instead of the Z axis.
bool	updatePosition = true
	Determines if the character should move or if just the desired velocities should be calculated.
bool	updateRotation = true
	Determines if the character should rotate automatically.

Protected Member Functions
virtual void	CalculateNextRotation (out Quaternion nextRotation)
override void	MovementUpdateInternal (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation)
	Called during either Update or FixedUpdate depending on if rigidbodies are used for movement or not.
override void	OnDisable ()
override int	OnUpgradeSerializedData (int version, bool unityThread)
	Handle serialization backwards compatibility.
Protected Member Functions inherited from AIBase
	AIBase ()
void	ApplyGravity (float deltaTime)
	Accelerates the agent downwards.
Vector2	CalculateDeltaToMoveThisFrame (Vector2 position, float distanceToEndOfPath, float deltaTime)
	Calculates how far to move during a single frame.
virtual void	CalculatePathRequestEndpoints (out Vector3 start, out Vector3 end)
	Outputs the start point and end point of the next automatic path request.
void	CancelCurrentPathRequest ()
virtual Vector3	ClampToNavmesh (Vector3 position, out bool positionChanged)
	Constrains the character's position to lie on the navmesh.
virtual void	FindComponents ()
virtual void	FixedUpdate ()
	Called every physics update.
virtual void	OnDrawGizmos ()
virtual void	OnDrawGizmosSelected ()
virtual void	OnEnable ()
	Called when the component is enabled.
Vector3	RaycastPosition (Vector3 position, float lastElevation)
	Checks if the character is grounded and prevents ground penetration.
IEnumerator	RepeatTrySearchPath ()
	Tries to search for a path every repathRate seconds.
Quaternion	SimulateRotationTowards (Vector2 direction, float maxDegrees)
	Simulates rotating the agent towards the specified direction and returns the new rotation.
virtual void	Start ()
	Starts searching for paths.
virtual void	Update ()
	Called every frame.
void	UpdateVelocity ()
Protected Member Functions inherited from VersionedMonoBehaviour
virtual void	Awake ()

Protected Attributes
PathInterpolator	interpolator = new PathInterpolator()
	Helper which calculates points along the current path.
Path	path
	Current path which is followed.
Protected Attributes inherited from AIBase
CharacterController	controller
	Cached CharacterController component.
Vector2	lastDeltaPosition
	Amount which the character wants or tried to move with during the last frame.
float	lastDeltaTime
	Delta time used for movement during the last frame.
float	lastRepath = float.NegativeInfinity
	Time when the last path request was started.
int	prevFrame
	Last frame index when prevPosition1 was updated.
Vector3	prevPosition1
	Position of the character at the end of the last frame.
Vector3	prevPosition2
	Position of the character at the end of the frame before the last frame.
Rigidbody	rigid
	Cached Rigidbody component.
Rigidbody2D	rigid2D
	Cached Rigidbody component.
RVOController	rvoController
	Cached RVOController component.
Seeker	seeker
	Cached Seeker component.
Vector3	simulatedPosition
	Position of the agent.
Quaternion	simulatedRotation
	Rotation of the agent.
Transform	tr
	Cached Transform component.
Vector2	velocity2D
	Current desired velocity of the agent (does not include local avoidance and physics).
float	verticalVelocity
	Velocity due to gravity.
bool	waitingForPathCalculation = false
	Only when the previous path has been calculated should the script consider searching for a new path.

Properties
bool IAstarAI.	canMove [get, set]
	Enables or disables movement completely.
bool IAstarAI.	canSearch [get, set]
	Enables or disables recalculating the path at regular intervals.
bool	hasPath [get]
	True if this agent currently has a path that it follows.
float IAstarAI.	maxSpeed [get, set]
	Max speed in world units per second.
bool	pathPending [get]
	True if a path is currently being calculated.
float	remainingDistance [get]
	Remaining distance along the current path to the end of the path.
float	speed [get, set]
	Maximum speed in world units per second.
Vector3	steeringTarget [get]
	Point on the path which the agent is currently moving towards.
Vector3	targetDirection [get]
	Direction that the agent wants to move in (excluding physics and local avoidance).
bool	TargetReached [get]
	True if the end of the path has been reached.
bool	targetReached [get, set]
	True if the agent has reached the end of the current path.
float	turningSpeed [get, set]
	Rotation speed.
Properties inherited from AIBase
Vector3	desiredVelocity [get]
	Velocity that this agent wants to move with.
Vector3	destination [get, set]
	Position in the world that this agent should move to.
bool	isStopped [get, set]
	Gets or sets if the agent should stop moving.
System.Action	onSearchPath [get, set]
	Called when the agent recalculates its path.
Vector3	position [get]
	Position of the agent.
Quaternion	rotation [get]
	Rotation of the agent.
virtual bool	shouldRecalculatePath [get]
	True if the path should be automatically recalculated as soon as possible.
Transform	target [get, set]
	Target to move towards.
bool	usingGravity [get, set]
	Indicates if gravity is used during this frame.
Vector3	velocity [get]
	Actual velocity that the agent is moving with.
Properties inherited from IAstarAI
bool	canMove [get, set]
	Enables or disables movement completely.
bool	canSearch [get, set]
	Enables or disables recalculating the path at regular intervals.
Vector3	desiredVelocity [get]
	Velocity that this agent wants to move with.
Vector3	destination [get, set]
	Position in the world that this agent should move to.
bool	hasPath [get]
	True if this agent currently has a path that it follows.
bool	isStopped [get, set]
	Gets or sets if the agent should stop moving.
float	maxSpeed [get, set]
	Max speed in world units per second.
System.Action	onSearchPath [get, set]
	Called when the agent recalculates its path.
bool	pathPending [get]
	True if a path is currently being calculated.
Vector3	position [get]
	Position of the agent.
float	remainingDistance [get]
	Remaining distance along the current path to the end of the path.
Quaternion	rotation [get]
	Rotation of the agent.
Vector3	steeringTarget [get]
	Point on the path which the agent is currently moving towards.
bool	targetReached [get]
	True if the agent has reached the end of the current path.
Vector3	velocity [get]
	Actual velocity that the agent is moving with.

Private Attributes
float	slowdown

Additional Inherited Members
Static Protected Attributes inherited from AIBase
static readonly Color	GizmoColorRaycast = new Color(118.0f/255, 206.0f/255, 112.0f/255)

Member Function Documentation

virtual void CalculateNextRotation ( out Quaternion  nextRotation )

protectedvirtual

Vector3 CalculateVelocity

(

Vector3

position

)

Current desired velocity of the agent (excluding physics and local avoidance but it includes gravity).

Deprecated:

This method no longer calculates the velocity. Use the desiredVelocity property instead.

override void MovementUpdateInternal ( float  deltaTime, out Vector3  nextPosition, out Quaternion  nextRotation  )

protectedvirtual

Called during either Update or FixedUpdate depending on if rigidbodies are used for movement or not.

Implements AIBase.

override void OnDisable ( )

protectedvirtual

Reimplemented from AIBase.

override void OnPathComplete ( Path  newPath )

virtual

Called when a requested path has been calculated.

A path is first requested by #UpdatePath, it is then calculated, probably in the same or the next frame. Finally it is returned to the seeker which forwards it to this function.

Implements AIBase.

Reimplemented in LegacyAIPath.

virtual void OnTargetReached ( )

virtual

The end of the path has been reached.

If you want custom logic for when the AI has reached it's destination add it here. You can also create a new script which inherits from this one and override the function in that script.

This method will be called again if a new path is calculated as the destination may have changed. So when the agent is close to the destination this method will typically be called every repathRate seconds.

Reimplemented in MineBotAI.

override int OnUpgradeSerializedData ( int  version, bool  unityThread  )

protectedvirtual

Handle serialization backwards compatibility.

Reimplemented from AIBase.

override void Teleport ( Vector3  newPosition, bool  clearPath = true  )

virtual

Instantly move the agent to a new position.

This will trigger a path recalculation (if clearPath is true, which is the default) so if you want to teleport the agent and change its destination it is recommended that you set the destination before calling this method.The current path will be cleared by default.

See Also

Works similarly to Unity's NavmeshAgent.Warp.

SearchPath

Reimplemented from AIBase.

Member Data Documentation

bool alwaysDrawGizmos

Draws detailed gizmos constantly in the scene view instead of only when the agent is selected and settings are being modified.

float endReachedDistance = 0.2F

Distance to the end point to consider the end of path to be reached.

When the end is within this distance then OnTargetReached will be called and TargetReached will return true.

PathInterpolator interpolator = new PathInterpolator()

protected

Helper which calculates points along the current path.

Path path

protected

Current path which is followed.

float pickNextWaypointDist = 2

Determines within what range it will switch to target the next waypoint in the path.

float rotationSpeed = 360

Rotation speed.

Rotation is calculated using Quaternion.RotateTowards. This variable represents the rotation speed in degrees per second. The higher it is, the faster the character will be able to rotate.

float slowdown

private

float slowdownDistance = 0.6F

Distance from the target point where the AI will start to slow down.

Note that this doesn't only affect the end point of the path but also any intermediate points, so be sure to set pickNextWaypointDist to a higher value than this

bool slowWhenNotFacingTarget = true

Slow down when not facing the target direction.

Incurs at a small performance overhead.

CloseToDestinationMode whenCloseToDestination = CloseToDestinationMode.Stop

What to do when within endReachedDistance units from the destination.

The character can either stop immediately when it comes within that distance, which is useful for e.g archers or other ranged units that want to fire on a target. Or the character can continue to try to reach the exact destination point and come to a full stop there. This is useful if you want the character to reach the exact point that you specified.

Note that targetReached will become true when the character is within endReachedDistance units from the destination regardless of what this field is set to.

Property Documentation

bool IAstarAI. canMove

getsetprivate

Enables or disables movement completely.

If you want the agent to stand still, but still react to local avoidance and use gravity: use isStopped instead.

See Also

canSearch

isStopped

bool IAstarAI. canSearch

getsetprivate

Enables or disables recalculating the path at regular intervals.

Setting this to false does not stop any active path requests from being calculated or stop it from continuing to follow the current path.Note that this only disables automatic path recalculations. If you call the SearchPath() method a path will still be calculated.

See Also

canMove

isStopped

bool hasPath

get

True if this agent currently has a path that it follows.

float IAstarAI. maxSpeed

getsetprivate

Max speed in world units per second.

bool pathPending

get

True if a path is currently being calculated.

float remainingDistance

get

Remaining distance along the current path to the end of the path.

For the RichAI movement script this may not always be precisely known, especially when far away from the destination. In those cases an approximate distance will be returned.If the agent does not currently have a path, then positive infinity will be returned.

float speed

getset

Maximum speed in world units per second.

Deprecated:

Use maxSpeed instead

Vector3 steeringTarget

get

Point on the path which the agent is currently moving towards.

This is usually a point a small distance ahead of the agent or the end of the path.If the agent does not have a path at the moment, then the agent's current position will be returned.

Vector3 targetDirection

get

Direction that the agent wants to move in (excluding physics and local avoidance).

Deprecated:

Only exists for compatibility reasons. Use desiredVelocity or steeringTarget instead instead.

bool TargetReached

get

True if the end of the path has been reached.

Deprecated:

When unifying the interfaces for different movement scripts, this property has been renamed to targetReached (lowercase t)

bool targetReached

getset

True if the agent has reached the end of the current path.

float turningSpeed

getset

Rotation speed.

Deprecated:

This field has been renamed to rotationSpeed and is now in degrees per second instead of a damping factor.

---

The documentation for this class was generated from the following files:

• /Users/arong/Unity/a-pathfinding-project/Assets/AstarPathfindingProject/Core/AI/AIPath.cs
• /Users/arong/Unity/a-pathfinding-project/Assets/AstarPathfindingProject/Legacy/MiscLegacy.cs