com.badlogic.gdx.ai.steer.behaviors.Alignment Maven / Gradle / Ivy
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* Copyright 2014 See AUTHORS file.
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* Licensed under the Apache License, Version 2.0 (the "License");
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package com.badlogic.gdx.ai.steer.behaviors;
import com.badlogic.gdx.ai.steer.GroupBehavior;
import com.badlogic.gdx.ai.steer.Limiter;
import com.badlogic.gdx.ai.steer.Proximity;
import com.badlogic.gdx.ai.steer.Proximity.ProximityCallback;
import com.badlogic.gdx.ai.steer.Steerable;
import com.badlogic.gdx.ai.steer.SteeringAcceleration;
import com.badlogic.gdx.math.Vector;
/** {@code Alignment} is a group behavior producing a linear acceleration that attempts to keep the owner aligned with the agents in
* its immediate area defined by the given {@link Proximity}. The acceleration is calculated by first iterating through all the
* neighbors and averaging their linear velocity vectors. This value is the desired direction, so we just subtract the owner's
* linear velocity to get the steering output.
*
* Cars moving along roads demonstrate {@code Alignment} type behavior. They also demonstrate {@link Separation} as they try to
* keep a minimum distance from each other.
*
* @param Type of vector, either 2D or 3D, implementing the {@link Vector} interface
*
* @author davebaol */
public class Alignment> extends GroupBehavior implements ProximityCallback {
private T averageVelocity;
/** Creates an {@code Alignment} behavior for the specified owner and proximity.
* @param owner the owner of this behavior
* @param proximity the proximity */
public Alignment (Steerable owner, Proximity proximity) {
super(owner, proximity);
}
@Override
protected SteeringAcceleration calculateRealSteering (SteeringAcceleration steering) {
steering.setZero();
averageVelocity = steering.linear;
int neighborCount = proximity.findNeighbors(this);
if (neighborCount > 0) {
// Average the accumulated velocities
averageVelocity.scl(1f / neighborCount);
// Match the average velocity.
// Notice that steering.linear and averageVelocity are the same vector here.
averageVelocity.sub(owner.getLinearVelocity()).limit(getActualLimiter().getMaxLinearAcceleration());
}
return steering;
}
@Override
public boolean reportNeighbor (Steerable neighbor) {
// Accumulate neighbor velocity
averageVelocity.add(neighbor.getLinearVelocity());
return true;
}
//
// Setters overridden in order to fix the correct return type for chaining
//
@Override
public Alignment setOwner (Steerable owner) {
this.owner = owner;
return this;
}
@Override
public Alignment setEnabled (boolean enabled) {
this.enabled = enabled;
return this;
}
/** Sets the limiter of this steering behavior. The given limiter must at least take care of the maximum linear acceleration.
* @return this behavior for chaining. */
@Override
public Alignment setLimiter (Limiter limiter) {
this.limiter = limiter;
return this;
}
}