Hide (libGDX AI)

java.lang.Object
- com.badlogic.gdx.ai.steer.SteeringBehavior<T>
- - com.badlogic.gdx.ai.steer.behaviors.Arrive<T>
  - - com.badlogic.gdx.ai.steer.behaviors.Hide<T>

Type Parameters:

T - Type of vector, either 2D or 3D, implementing the Vector interface

All Implemented Interfaces:

Proximity.ProximityCallback<T>
```
public class Hide<T extends com.badlogic.gdx.math.Vector<T>>
extends Arrive<T>
implements Proximity.ProximityCallback<T>
```
This behavior attempts to position a owner so that an obstacle is always between itself and the agent (the hunter) it's trying to hide from. First the distance to each of these obstacles is determined. Then the owner uses the arrive behavior to steer toward the closest one. If no appropriate obstacles can be found, no steering is returned.
You can use this behavior not only for situations where you require a non-player character (NPC) to hide from the player, like find cover when fired at, but also in situations where you would like an NPC to sneak up on a player. For example, you can create an NPC capable of stalking a player through a gloomy forest, darting from tree to tree.
It's worth mentioning that since this behavior can produce no steering acceleration it is commonly used with PrioritySteering. For instance, to make the owner go away from the target if there are no obstacles nearby to hide behind, just use Hide and Evade behaviors with this priority order.
There are a few interesting modifications you might want to make to this behavior:
- With FieldOfViewProximity you can allow the owner to hide only if the target is within its field of view. This tends to produce unsatisfactory performance though, because the owner starts to act like a child hiding from monsters beneath the bed sheets, something like "if you can't see it, then it can't see you" effect making the owner look dumb. This can be countered slightly though by adding in a time effect so that the owner will hide if the target is visible or if it has seen the target within the last N seconds. This gives it a sort of memory and produces reasonable-looking behavior.
- The same as above, but this time the owner only tries to hide if the owner can see the target and the target can see the owner.
- It might be desirable to produce a force that steers the owner so that it always favors hiding positions that are to the side or rear of the pursuer. This can be achieved easily using the dot product to bias the distances returned from the method getHidingPosition(T, float, T).
- At the beginning of any of the methods a check can be made to test if the target is within a "threat distance" before proceeding with any further calculations. If the target is not a threat, then the method can return immediately with zero steering.

Field Summary

Fields
Modifier and Type	Field and Description
`protected float`	`distanceFromBoundary` The distance from the boundary of the obstacle behind which to hide.
`protected Proximity<T>`	`proximity` The proximity to find nearby obstacles.

Fields inherited from class com.badlogic.gdx.ai.steer.behaviors.Arrive
arrivalTolerance, decelerationRadius, target, timeToTarget

Fields inherited from class com.badlogic.gdx.ai.steer.SteeringBehavior
enabled, limiter, owner

Constructor Summary

Constructors
Constructor and Description
`Hide(Steerable<T> owner)` Creates an `Hide` behavior for the specified owner.
`Hide(Steerable<T> owner, Location<T> target)` Creates a `Hide` behavior for the specified owner and target.
`Hide(Steerable<T> owner, Location<T> target, Proximity<T> proximity)` Creates a `Hide` behavior for the specified owner, target and proximity.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected SteeringAcceleration<T>`	`calculateRealSteering(SteeringAcceleration<T> steering)` Calculates the steering acceleration produced by this behavior and writes it to the given steering output.
`float`	`getDistanceFromBoundary()` Returns the distance from the boundary of the obstacle behind which to hide.
`protected T`	`getHidingPosition(T obstaclePosition, float obstacleRadius, T targetPosition)` Given the position of a target and the position and radius of an obstacle, this method calculates a position `distanceFromBoundary` away from the object's bounding radius and directly opposite the target.
`Proximity<T>`	`getProximity()` Returns the proximity used to find nearby obstacles.
`boolean`	`reportNeighbor(Steerable<T> neighbor)` The callback method used to report a neighbor.
`Hide<T>`	`setArrivalTolerance(float arrivalTolerance)` Sets the tolerance for arriving at the target.
`Hide<T>`	`setDecelerationRadius(float decelerationRadius)` Sets the radius for beginning to slow down.
`Hide<T>`	`setDistanceFromBoundary(float distanceFromBoundary)` Sets the distance from the boundary of the obstacle behind which to hide.
`Hide<T>`	`setEnabled(boolean enabled)` Sets this steering behavior on/off.
`Hide<T>`	`setLimiter(Limiter limiter)` Sets the limiter of this steering behavior.
`Hide<T>`	`setOwner(Steerable<T> owner)` Sets the owner of this steering behavior.
`Hide<T>`	`setProximity(Proximity<T> proximity)` Sets the proximity used to find nearby obstacles.
`Hide<T>`	`setTarget(Location<T> target)` Sets the target to arrive to.
`Hide<T>`	`setTimeToTarget(float timeToTarget)` Sets the time over which to achieve target speed.

Methods inherited from class com.badlogic.gdx.ai.steer.behaviors.Arrive
arrive, getArrivalTolerance, getDecelerationRadius, getTarget, getTimeToTarget

Methods inherited from class com.badlogic.gdx.ai.steer.SteeringBehavior
calculateSteering, getActualLimiter, getLimiter, getOwner, isEnabled, newVector

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - proximity
```
protected Proximity<T extends com.badlogic.gdx.math.Vector<T>> proximity
```
    The proximity to find nearby obstacles.
  - distanceFromBoundary
```
protected float distanceFromBoundary
```
    The distance from the boundary of the obstacle behind which to hide.
- Constructor Detail
  - Hide
```
public Hide(Steerable<T> owner)
```
    Creates an Hide behavior for the specified owner.
    
    Parameters:
    
    owner - the owner of this behavior
  - Hide
```
public Hide(Steerable<T> owner,
            Location<T> target)
```
    Creates a Hide behavior for the specified owner and target.
    
    Parameters:
    
    owner - the owner of this behavior
    
    target - the target of this behavior
  - Hide
```
public Hide(Steerable<T> owner,
            Location<T> target,
            Proximity<T> proximity)
```
    Creates a Hide behavior for the specified owner, target and proximity.
    
    Parameters:
    
    owner - the owner of this behavior
    
    target - the target of this behavior
    
    proximity - the proximity to find nearby obstacles
- Method Detail
  - calculateRealSteering
```
protected SteeringAcceleration<T> calculateRealSteering(SteeringAcceleration<T> steering)
```
    Description copied from class: SteeringBehavior
    
    Calculates the steering acceleration produced by this behavior and writes it to the given steering output.
    This method is called by SteeringBehavior.calculateSteering(SteeringAcceleration) when this steering behavior is enabled.
    
    Overrides:
    
    calculateRealSteering in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Parameters:
    
    steering - the steering acceleration to be calculated.
    
    Returns:
    
    the calculated steering acceleration for chaining.
  - reportNeighbor
```
public boolean reportNeighbor(Steerable<T> neighbor)
```
    Description copied from interface: Proximity.ProximityCallback
    
    The callback method used to report a neighbor.
    
    Specified by:
    
    reportNeighbor in interface Proximity.ProximityCallback<T extends com.badlogic.gdx.math.Vector<T>>
    
    Parameters:
    
    neighbor - the reported neighbor.
    
    Returns:
    
    true if the given neighbor is valid; false otherwise.
  - getProximity
```
public Proximity<T> getProximity()
```
    Returns the proximity used to find nearby obstacles.
  - setProximity
```
public Hide<T> setProximity(Proximity<T> proximity)
```
    Sets the proximity used to find nearby obstacles.
    
    Parameters:
    
    proximity - the proximity to set
    
    Returns:
    
    this behavior for chaining.
  - getDistanceFromBoundary
```
public float getDistanceFromBoundary()
```
    Returns the distance from the boundary of the obstacle behind which to hide.
  - setDistanceFromBoundary
```
public Hide<T> setDistanceFromBoundary(float distanceFromBoundary)
```
    Sets the distance from the boundary of the obstacle behind which to hide.
    
    Parameters:
    
    distanceFromBoundary - the distance to set
    
    Returns:
    
    this behavior for chaining.
  - getHidingPosition
```
protected T getHidingPosition(T obstaclePosition,
                              float obstacleRadius,
                              T targetPosition)
```
    Given the position of a target and the position and radius of an obstacle, this method calculates a position distanceFromBoundary away from the object's bounding radius and directly opposite the target. It does this by scaling the normalized "to obstacle" vector by the required distance away from the center of the obstacle and then adding the result to the obstacle's position.
    
    Parameters:
    
    obstaclePosition -
    
    obstacleRadius -
    
    targetPosition -
    
    Returns:
    
    the hiding position behind the obstacle.
  - setOwner
```
public Hide<T> setOwner(Steerable<T> owner)
```
    Description copied from class: SteeringBehavior
    
    Sets the owner of this steering behavior.
    
    Overrides:
    
    setOwner in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setEnabled
```
public Hide<T> setEnabled(boolean enabled)
```
    Description copied from class: SteeringBehavior
    
    Sets this steering behavior on/off.
    
    Overrides:
    
    setEnabled in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setLimiter
```
public Hide<T> setLimiter(Limiter limiter)
```
    Description copied from class: Arrive
    
    Sets the limiter of this steering behavior. The given limiter must at least take care of the maximum linear speed and acceleration.
    
    Overrides:
    
    setLimiter in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setTarget
```
public Hide<T> setTarget(Location<T> target)
```
    Description copied from class: Arrive
    
    Sets the target to arrive to.
    
    Overrides:
    
    setTarget in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setArrivalTolerance
```
public Hide<T> setArrivalTolerance(float arrivalTolerance)
```
    Description copied from class: Arrive
    
    Sets the tolerance for arriving at the target. It lets the owner get near enough to the target without letting small errors keep it in motion.
    
    Overrides:
    
    setArrivalTolerance in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setDecelerationRadius
```
public Hide<T> setDecelerationRadius(float decelerationRadius)
```
    Description copied from class: Arrive
    
    Sets the radius for beginning to slow down.
    
    Overrides:
    
    setDecelerationRadius in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.
  - setTimeToTarget
```
public Hide<T> setTimeToTarget(float timeToTarget)
```
    Description copied from class: Arrive
    
    Sets the time over which to achieve target speed.
    
    Overrides:
    
    setTimeToTarget in class Arrive<T extends com.badlogic.gdx.math.Vector<T>>
    
    Returns:
    
    this behavior for chaining.

Class Hide<T extends com.badlogic.gdx.math.Vector<T>>

Field Summary

Fields inherited from class com.badlogic.gdx.ai.steer.behaviors.Arrive

Fields inherited from class com.badlogic.gdx.ai.steer.SteeringBehavior

Constructor Summary

Method Summary

Methods inherited from class com.badlogic.gdx.ai.steer.behaviors.Arrive

Methods inherited from class com.badlogic.gdx.ai.steer.SteeringBehavior

Methods inherited from class java.lang.Object

Field Detail

proximity

distanceFromBoundary

Constructor Detail

Hide

Hide

Hide

Method Detail

calculateRealSteering

reportNeighbor

getProximity

setProximity

getDistanceFromBoundary

setDistanceFromBoundary

getHidingPosition

setOwner

setEnabled

setLimiter

setTarget

setArrivalTolerance

setDecelerationRadius

setTimeToTarget