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 is not written for high performance, so I do not recommend using it for large groups of units.
This script will try to follow a target transform, in regular intervals, the path to that target will be recalculated. It will on FixedUpdate try to move towards the next point in the path. However it will only move in the forward direction, but it will rotate around it's Y-axis to make it reach the target.
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 turningSpeed, however slowdownDistance might require some explanation. It is the approximate distance from the target 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 forwardLook and pickNextWaypointDist to a higher value than this.
pickNextWaypointDist is simply determines within what range it will switch to target the next waypoint in the path.
forwardLook will try to calculate an interpolated target point on the current segment in the path so that it has a distance of forwardLook from the AI
Below is an image illustrating several variables as well as some internal ones, but which are relevant for understanding how it works. Note that the forwardLook range will not match up exactly with the target point practically, even though that's the goal.
This script has many movement fallbacks. If it finds a NavmeshController, it will use that, otherwise it will look for a character controller, then for a rigidbody and if it hasn't been able to find any it will use Transform.Translate which is guaranteed to always work.
- Deprecated:
- Use the AIPath class instead. This class only exists for compatibility reasons.
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| override void | OnPathComplete (Path _p) |
| | Called when a requested path has finished calculation. More...
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| Vector3 | CalculateVelocity (Vector3 position) |
| | Current desired velocity of the agent (excluding physics and local avoidance but it includes gravity). More...
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| virtual void | OnTargetReached () |
| | The end of the path has been reached. More...
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| override void | Teleport (Vector3 newPosition, bool clearPath=true) |
| | Instantly move the agent to a new position. More...
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| virtual void | FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation) |
| | Moves the agent to a position. More...
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| virtual Vector3 | GetFeetPosition () |
| | Position of the base of the character. More...
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| virtual void | Move (Vector3 deltaPosition) |
| | Move the agent. More...
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| void | MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation) |
| | Calculate how the character wants to move during this frame. More...
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| virtual void | SearchPath () |
| | Recalculate the current path. More...
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| Quaternion | SimulateRotationTowards (Vector3 direction, float maxDegrees) |
| | Simulates rotating the agent towards the specified direction and returns the new rotation. More...
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| void | FinalizeMovement (Vector3 nextPosition, Quaternion nextRotation) |
| | Move the agent. More...
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| void | Move (Vector3 deltaPosition) |
| | Move the agent. More...
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| void | MovementUpdate (float deltaTime, out Vector3 nextPosition, out Quaternion nextRotation) |
| | Calculate how the character wants to move during this frame. More...
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| void | SearchPath () |
| | Recalculate the current path. More...
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| override void | Awake () |
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| Vector3 | CalculateTargetPoint (Vector3 p, Vector3 a, Vector3 b) |
| | Calculates target point from the current line segment. More...
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| new Vector3 | CalculateVelocity (Vector3 currentPosition) |
| | Calculates desired velocity. More...
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| void | RotateTowards (Vector3 dir) |
| | Rotates in the specified direction. More...
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| override void | Update () |
| | Called every frame. More...
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| float | XZSqrMagnitude (Vector3 a, Vector3 b) |
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| virtual void | CalculateNextRotation (float slowdown, out Quaternion nextRotation) |
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| 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...
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| override void | OnDisable () |
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| override int | OnUpgradeSerializedData (int version, bool unityThread) |
| | Handle serialization backwards compatibility. More...
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| | AIBase () |
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| void | ApplyGravity (float deltaTime) |
| | Accelerates the agent downwards. More...
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| Vector2 | CalculateDeltaToMoveThisFrame (Vector2 position, float distanceToEndOfPath, float deltaTime) |
| | Calculates how far to move during a single frame. More...
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| virtual void | CalculatePathRequestEndpoints (out Vector3 start, out Vector3 end) |
| | Outputs the start point and end point of the next automatic path request. More...
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| void | CancelCurrentPathRequest () |
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| virtual Vector3 | ClampToNavmesh (Vector3 position, out bool positionChanged) |
| | Constrains the character's position to lie on the navmesh. More...
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| virtual void | FindComponents () |
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| virtual void | FixedUpdate () |
| | Called every physics update. More...
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| virtual void | OnDrawGizmos () |
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| virtual void | OnDrawGizmosSelected () |
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| virtual void | OnEnable () |
| | Called when the component is enabled. More...
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| Vector3 | RaycastPosition (Vector3 position, float lastElevation) |
| | Checks if the character is grounded and prevents ground penetration. More...
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| IEnumerator | RepeatTrySearchPath () |
| | Tries to search for a path every repathRate seconds. More...
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| Quaternion | SimulateRotationTowards (Vector2 direction, float maxDegrees) |
| | Simulates rotating the agent towards the specified direction and returns the new rotation. More...
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| virtual void | Start () |
| | Starts searching for paths. More...
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| void | UpdateVelocity () |
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| static readonly Color | GizmoColorRaycast = new Color(118.0f/255, 206.0f/255, 112.0f/255) |
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| bool IAstarAI. | canMove [get, set] |
| | Enables or disables movement completely. More...
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| bool IAstarAI. | canSearch [get, set] |
| | Enables or disables recalculating the path at regular intervals. More...
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| bool | hasPath [get] |
| | True if this agent currently has a path that it follows. More...
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| float IAstarAI. | maxSpeed [get, set] |
| | Max speed in world units per second. More...
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| bool | pathPending [get] |
| | True if a path is currently being calculated. More...
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| bool | reachedEndOfPath [get, protected set] |
| | True if the agent has reached the end of the current path. More...
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| float | remainingDistance [get] |
| | Remaining distance along the current path to the end of the path. More...
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| float | speed [get, set] |
| | Maximum speed in world units per second. More...
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| Vector3 | steeringTarget [get] |
| | Point on the path which the agent is currently moving towards. More...
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| Vector3 | targetDirection [get] |
| | Direction that the agent wants to move in (excluding physics and local avoidance). More...
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| bool | TargetReached [get] |
| | True if the end of the path has been reached. More...
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| float | turningSpeed [get, set] |
| | Rotation speed. More...
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| Vector3 | desiredVelocity [get] |
| | Velocity that this agent wants to move with. More...
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| Vector3 | destination [get, set] |
| | Position in the world that this agent should move to. More...
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| bool | isStopped [get, set] |
| | Gets or sets if the agent should stop moving. More...
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| System.Action | onSearchPath [get, set] |
| | Called when the agent recalculates its path. More...
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| Vector3 | position [get] |
| | Position of the agent. More...
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| Quaternion | rotation [get] |
| | Rotation of the agent. More...
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| virtual bool | shouldRecalculatePath [get] |
| | True if the path should be automatically recalculated as soon as possible. More...
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| Transform | target [get, set] |
| | Target to move towards. More...
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| bool | usingGravity [get, private set] |
| | Indicates if gravity is used during this frame. More...
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| Vector3 | velocity [get] |
| | Actual velocity that the agent is moving with. More...
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| bool | canMove [get, set] |
| | Enables or disables movement completely. More...
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| bool | canSearch [get, set] |
| | Enables or disables recalculating the path at regular intervals. More...
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| Vector3 | desiredVelocity [get] |
| | Velocity that this agent wants to move with. More...
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| Vector3 | destination [get, set] |
| | Position in the world that this agent should move to. More...
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| bool | hasPath [get] |
| | True if this agent currently has a path that it follows. More...
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| bool | isStopped [get, set] |
| | Gets or sets if the agent should stop moving. More...
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| float | maxSpeed [get, set] |
| | Max speed in world units per second. More...
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| System.Action | onSearchPath [get, set] |
| | Called when the agent recalculates its path. More...
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| bool | pathPending [get] |
| | True if a path is currently being calculated. More...
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| Vector3 | position [get] |
| | Position of the agent. More...
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| bool | reachedEndOfPath [get] |
| | True if the agent has reached the end of the current path. More...
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| float | remainingDistance [get] |
| | Remaining distance along the current path to the end of the path. More...
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| Quaternion | rotation [get] |
| | Rotation of the agent. More...
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| Vector3 | steeringTarget [get] |
| | Point on the path which the agent is currently moving towards. More...
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| Vector3 | velocity [get] |
| | Actual velocity that the agent is moving with. More...
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| bool closestOnPathCheck = true |
Do a closest point on path check when receiving path callback.
Usually the AI has moved a bit between requesting the path, and getting it back, and there is usually a small gap between the AI and the closest node. If this option is enabled, it will simulate, when the path callback is received, movement between the closest node and the current AI position. This helps to reduce the moments when the AI just get a new path back, and thinks it ought to move backwards to the start of the new path even though it really should just proceed forward.
Public Member Functions inherited from AIPath