com.badlogic.gdx.ai.steer.behaviors

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

java.lang.Object

com.badlogic.gdx.ai.steer.SteeringBehavior<T>

com.badlogic.gdx.ai.steer.behaviors.BlendedSteering<T>

Type Parameters:

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

public class BlendedSteering<T extends com.badlogic.gdx.math.Vector<T>>
extends SteeringBehavior<T>

This combination behavior simply sums up all the behaviors, applies their weights, and truncates the result before returning. There are no constraints on the blending weights; they don't have to sum to one, for example, and rarely do. Don't think of BlendedSteering as a weighted mean, because it's not.

With BlendedSteering you can combine multiple behaviors to get a more complex behavior. It can work fine, but the trade-off is that it comes with a few problems:

• Since every active behavior is calculated every time step, it can be a costly method to process.
• Behavior weights can be difficult to tweak. There have been research projects that have tried to evolve the steering weights using genetic algorithms or neural networks. Results have not been encouraging, however, and manual experimentation still seems to be the most sensible approach.
• It's problematic with conflicting forces. For instance, a common scenario is where an agent is backed up against a wall by several other agents. In this example, the separating forces from the neighboring agents can be greater than the repulsive force from the wall and the agent can end up being pushed through the wall boundary. This is almost certainly not going to be favorable. Sure you can make the weights for the wall avoidance huge, but then your agent may behave strangely next time it finds itself alone and next to a wall.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BlendedSteering.BehaviorAndWeight<T extends com.badlogic.gdx.math.Vector<T>>

Field Summary

Fields

Modifier and Type	Field and Description
protected com.badlogic.gdx.utils.Array<BlendedSteering.BehaviorAndWeight<T>>	list The list of behaviors and their corresponding blending weights.

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

enabled, limiter, owner

Constructor Summary

Constructors

Constructor and Description
BlendedSteering(Steerable<T> owner) Creates a BlendedSteering for the specified owner, maxLinearAcceleration and maxAngularAcceleration.

Method Summary

Modifier and Type	Method and Description
BlendedSteering<T>	add(BlendedSteering.BehaviorAndWeight<T> item) Adds a steering behavior and its weight to the list.
BlendedSteering<T>	add(SteeringBehavior<T> behavior, float weight) Adds a steering behavior and its weight to the list.
protected SteeringAcceleration<T>	calculateRealSteering(SteeringAcceleration<T> blendedSteering) Calculates the steering acceleration produced by this behavior and writes it to the given steering output.
BlendedSteering.BehaviorAndWeight<T>	get(int index) Returns the weighted behavior at the specified index.
void	remove(BlendedSteering.BehaviorAndWeight<T> item) Removes a steering behavior from the list.
void	remove(SteeringBehavior<T> behavior) Removes a steering behavior from the list.
BlendedSteering<T>	setEnabled(boolean enabled) Sets this steering behavior on/off.
BlendedSteering<T>	setLimiter(Limiter limiter) Sets the limiter of this steering behavior.
BlendedSteering<T>	setOwner(Steerable<T> owner) Sets the owner of this steering behavior.

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

list

protected com.badlogic.gdx.utils.Array<BlendedSteering.BehaviorAndWeight<T extends com.badlogic.gdx.math.Vector<T>>> list

The list of behaviors and their corresponding blending weights.

Constructor Detail

BlendedSteering

public BlendedSteering(Steerable<T> owner)

Creates a BlendedSteering for the specified owner, maxLinearAcceleration and maxAngularAcceleration.

Parameters:

owner - the owner of this behavior.

Method Detail

add

public BlendedSteering<T> add(SteeringBehavior<T> behavior,
                              float weight)

Adds a steering behavior and its weight to the list.

Parameters:

behavior - the steering behavior to add

weight - the weight of the behavior

Returns:

this behavior for chaining.

add

public BlendedSteering<T> add(BlendedSteering.BehaviorAndWeight<T> item)

Adds a steering behavior and its weight to the list.

Parameters:

item - the steering behavior and its weight

Returns:

this behavior for chaining.

remove

public void remove(BlendedSteering.BehaviorAndWeight<T> item)

Removes a steering behavior from the list.

Parameters:

item - the steering behavior to remove

remove

public void remove(SteeringBehavior<T> behavior)

Removes a steering behavior from the list.

Parameters:

behavior - the steering behavior to remove

get

public BlendedSteering.BehaviorAndWeight<T> get(int index)

Returns the weighted behavior at the specified index.

Parameters:

index - the index of the weighted behavior to return

calculateRealSteering

protected SteeringAcceleration<T> calculateRealSteering(SteeringAcceleration<T> blendedSteering)

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.

Specified by:

calculateRealSteering in class SteeringBehavior<T extends com.badlogic.gdx.math.Vector<T>>

Parameters:

blendedSteering - the steering acceleration to be calculated.

Returns:

the calculated steering acceleration for chaining.

setOwner

public BlendedSteering<T> setOwner(Steerable<T> owner)

Description copied from class: SteeringBehavior

Sets the owner of this steering behavior.

Overrides:

setOwner in class SteeringBehavior<T extends com.badlogic.gdx.math.Vector<T>>

Returns:

this behavior for chaining.

setEnabled

public BlendedSteering<T> setEnabled(boolean enabled)

Description copied from class: SteeringBehavior

Sets this steering behavior on/off.

Overrides:

setEnabled in class SteeringBehavior<T extends com.badlogic.gdx.math.Vector<T>>

Returns:

this behavior for chaining.

setLimiter

public BlendedSteering<T> setLimiter(Limiter limiter)

Sets the limiter of this steering behavior. The given limiter must at least take care of the maximum linear and angular accelerations. You can use NullLimiter.NEUTRAL_LIMITER to avoid all truncations.

Overrides:

setLimiter in class SteeringBehavior<T extends com.badlogic.gdx.math.Vector<T>>

Returns:

this behavior for chaining.