A* Pathfinding Project
4.1.7
The A* Pathfinding Project for Unity 3D
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AI for following paths. More...
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.
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.
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). More... | |
override void | OnPathComplete (Path newPath) |
Called when a requested path has been calculated. More... | |
virtual void | OnTargetReached () |
The end of the path has been reached. More... | |
override void | Teleport (Vector3 newPosition, bool clearPath=true) |
Instantly move the agent to a new position. More... | |
Public Member Functions inherited from AIBase | |
virtual void | FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation) |
Moves the agent to a position. More... | |
virtual Vector3 | GetFeetPosition () |
Position of the base of the character. More... | |
virtual void | Move (Vector3 deltaPosition) |
Move the agent. More... | |
void | MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation) |
Calculate how the character wants to move during this frame. More... | |
virtual void | SearchPath () |
Recalculate the current path. More... | |
Quaternion | SimulateRotationTowards (Vector3 direction, float maxDegrees) |
Simulates rotating the agent towards the specified direction and returns the new rotation. More... | |
Public Member Functions inherited from IAstarAI | |
void | FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation) |
Move the agent. More... | |
void | Move (Vector3 deltaPosition) |
Move the agent. More... | |
void | MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation) |
Calculate how the character wants to move during this frame. More... | |
void | SearchPath () |
Recalculate the current path. More... | |
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. More... | |
float | endReachedDistance = 0.2F |
Distance to the end point to consider the end of path to be reached. More... | |
float | pickNextWaypointDist = 2 |
Determines within what range it will switch to target the next waypoint in the path. More... | |
float | rotationSpeed = 360 |
Rotation speed. More... | |
float | slowdownDistance = 0.6F |
Distance from the end of the path where the AI will start to slow down. More... | |
bool | slowWhenNotFacingTarget = true |
Slow down when not facing the target direction. More... | |
CloseToDestinationMode | whenCloseToDestination = CloseToDestinationMode.Stop |
What to do when within endReachedDistance units from the destination. More... | |
Public Attributes inherited from AIBase | |
bool | canMove = true |
Enables or disables movement completely. More... | |
bool | canSearch = true |
Enables or disables recalculating the path at regular intervals. More... | |
float | centerOffset = 1 |
Offset along the Y coordinate for the ground raycast start position. More... | |
Vector3 | gravity = new Vector3(float.NaN, float.NaN, float.NaN) |
Gravity to use. More... | |
LayerMask | groundMask = -1 |
Layer mask to use for ground placement. More... | |
float | maxSpeed = 1 |
Max speed in world units per second. More... | |
IMovementPlane | movementPlane = GraphTransform.identityTransform |
Plane which this agent is moving in. More... | |
float | repathRate = 0.5f |
Determines how often the agent will search for new paths (in seconds). More... | |
bool | rotationIn2D = false |
If true, the forward axis of the character will be along the Y axis instead of the Z axis. More... | |
bool | updatePosition = true |
Determines if the character's position should be coupled to the Transform's position. More... | |
bool | updateRotation = true |
Determines if the character's rotation should be coupled to the Transform's rotation. More... | |
Protected Member Functions | |
virtual void | CalculateNextRotation (float slowdown, 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. More... | |
override void | OnDisable () |
override int | OnUpgradeSerializedData (int version, bool unityThread) |
Handle serialization backwards compatibility. More... | |
virtual void | UpdateMovementPlane () |
Protected Member Functions inherited from AIBase | |
AIBase () | |
void | ApplyGravity (float deltaTime) |
Accelerates the agent downwards. More... | |
Vector2 | CalculateDeltaToMoveThisFrame (Vector2 position, float distanceToEndOfPath, float deltaTime) |
Calculates how far to move during a single frame. More... | |
virtual void | CalculatePathRequestEndpoints (out Vector3 start, out Vector3 end) |
Outputs the start point and end point of the next automatic path request. More... | |
void | CancelCurrentPathRequest () |
virtual Vector3 | ClampToNavmesh (Vector3 position, out bool positionChanged) |
Constrains the character's position to lie on the navmesh. More... | |
virtual void | FindComponents () |
virtual void | FixedUpdate () |
Called every physics update. More... | |
virtual void | OnDrawGizmos () |
virtual void | OnDrawGizmosSelected () |
virtual void | OnEnable () |
Called when the component is enabled. More... | |
Vector3 | RaycastPosition (Vector3 position, float lastElevation) |
Checks if the character is grounded and prevents ground penetration. More... | |
IEnumerator | RepeatTrySearchPath () |
Tries to search for a path every repathRate seconds. More... | |
Quaternion | SimulateRotationTowards (Vector2 direction, float maxDegrees) |
Simulates rotating the agent towards the specified direction and returns the new rotation. More... | |
virtual void | Start () |
Starts searching for paths. More... | |
virtual void | Update () |
Called every frame. More... | |
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. More... | |
Path | path |
Current path which is followed. More... | |
Protected Attributes inherited from AIBase | |
CharacterController | controller |
Cached CharacterController component. More... | |
Vector2 | lastDeltaPosition |
Amount which the character wants or tried to move with during the last frame. More... | |
float | lastDeltaTime |
Delta time used for movement during the last frame. More... | |
float | lastRepath = float.NegativeInfinity |
Time when the last path request was started. More... | |
int | prevFrame |
Last frame index when prevPosition1 was updated. More... | |
Vector3 | prevPosition1 |
Position of the character at the end of the last frame. More... | |
Vector3 | prevPosition2 |
Position of the character at the end of the frame before the last frame. More... | |
Rigidbody | rigid |
Cached Rigidbody component. More... | |
Rigidbody2D | rigid2D |
Cached Rigidbody component. More... | |
RVOController | rvoController |
Cached RVOController component. More... | |
Seeker | seeker |
Cached Seeker component. More... | |
Vector3 | simulatedPosition |
Position of the agent. More... | |
Quaternion | simulatedRotation |
Rotation of the agent. More... | |
Transform | tr |
Cached Transform component. More... | |
Vector2 | velocity2D |
Current desired velocity of the agent (does not include local avoidance and physics). More... | |
float | verticalVelocity |
Velocity due to gravity. More... | |
bool | waitingForPathCalculation = false |
Only when the previous path has been calculated should the script consider searching for a new path. More... | |
Properties | |
bool IAstarAI. | canMove [get, set] |
Enables or disables movement completely. More... | |
bool IAstarAI. | canSearch [get, set] |
Enables or disables recalculating the path at regular intervals. More... | |
bool | hasPath [get] |
True if this agent currently has a path that it follows. More... | |
float IAstarAI. | maxSpeed [get, set] |
Max speed in world units per second. More... | |
bool | pathPending [get] |
True if a path is currently being calculated. More... | |
float | remainingDistance [get] |
Remaining distance along the current path to the end of the path. More... | |
float | speed [get, set] |
Maximum speed in world units per second. More... | |
Vector3 | steeringTarget [get] |
Point on the path which the agent is currently moving towards. More... | |
Vector3 | targetDirection [get] |
Direction that the agent wants to move in (excluding physics and local avoidance). More... | |
bool | TargetReached [get] |
True if the end of the path has been reached. More... | |
bool | targetReached [get, protected set] |
True if the agent has reached the end of the current path. More... | |
float | turningSpeed [get, set] |
Rotation speed. More... | |
Properties inherited from AIBase | |
Vector3 | desiredVelocity [get] |
Velocity that this agent wants to move with. More... | |
Vector3 | destination [get, set] |
Position in the world that this agent should move to. More... | |
bool | isStopped [get, set] |
Gets or sets if the agent should stop moving. More... | |
System.Action | onSearchPath [get, set] |
Called when the agent recalculates its path. More... | |
Vector3 | position [get] |
Position of the agent. More... | |
Quaternion | rotation [get] |
Rotation of the agent. More... | |
virtual bool | shouldRecalculatePath [get] |
True if the path should be automatically recalculated as soon as possible. More... | |
Transform | target [get, set] |
Target to move towards. More... | |
bool | usingGravity [get, private set] |
Indicates if gravity is used during this frame. More... | |
Vector3 | velocity [get] |
Actual velocity that the agent is moving with. More... | |
Properties inherited from IAstarAI | |
bool | canMove [get, set] |
Enables or disables movement completely. More... | |
bool | canSearch [get, set] |
Enables or disables recalculating the path at regular intervals. More... | |
Vector3 | desiredVelocity [get] |
Velocity that this agent wants to move with. More... | |
Vector3 | destination [get, set] |
Position in the world that this agent should move to. More... | |
bool | hasPath [get] |
True if this agent currently has a path that it follows. More... | |
bool | isStopped [get, set] |
Gets or sets if the agent should stop moving. More... | |
float | maxSpeed [get, set] |
Max speed in world units per second. More... | |
System.Action | onSearchPath [get, set] |
Called when the agent recalculates its path. More... | |
bool | pathPending [get] |
True if a path is currently being calculated. More... | |
Vector3 | position [get] |
Position of the agent. More... | |
float | remainingDistance [get] |
Remaining distance along the current path to the end of the path. More... | |
Quaternion | rotation [get] |
Rotation of the agent. More... | |
Vector3 | steeringTarget [get] |
Point on the path which the agent is currently moving towards. More... | |
bool | targetReached [get] |
True if the agent has reached the end of the current path. More... | |
Vector3 | velocity [get] |
Actual velocity that the agent is moving with. More... | |
Additional Inherited Members | |
Static Protected Attributes inherited from AIBase | |
static readonly Color | GizmoColorRaycast = new Color(118.0f/255, 206.0f/255, 112.0f/255) |
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protectedvirtual |
Vector3 CalculateVelocity | ( | Vector3 | position | ) |
Current desired velocity of the agent (excluding physics and local avoidance but it includes gravity).
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protectedvirtual |
Called during either Update or FixedUpdate depending on if rigidbodies are used for movement or not.
Implements AIBase.
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protectedvirtual |
Reimplemented from AIBase.
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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.
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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.
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protectedvirtual |
Handle serialization backwards compatibility.
Reimplemented from AIBase.
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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.
Reimplemented from AIBase.
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protectedvirtual |
Reimplemented in AIArbitrarySurface.
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.
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protected |
Helper which calculates points along the current path.
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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 slowdownDistance = 0.6F |
Distance from the end of the path where the AI will start to slow down.
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.
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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.
This is also useful if you want to have full control over when the movement calculations run. Take a look at MovementUpdate
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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.
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get |
True if this agent currently has a path that it follows.
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getsetprivate |
Max speed in world units per second.
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get |
True if a path is currently being calculated.
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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.
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getset |
Maximum speed in world units per second.
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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.
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get |
Direction that the agent wants to move in (excluding physics and local avoidance).
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get |
True if the end of the path has been reached.
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getprotected set |
True if the agent has reached the end of the current path.
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getset |
Rotation speed.