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using UnityEngine;
namespace BehaviorDesigner.Runtime.Tasks.Movement
{
[TaskDescription("Pursue the target specified using the Unity NavMesh.")]
[TaskCategory("Movement")]
[HelpURL("https://www.opsive.com/support/documentation/behavior-designer-movement-pack/")]
[TaskIcon("Assets/Behavior Designer Movement/Editor/Icons/{SkinColor}PursueIcon.png")]
public class Pursue : NavMeshMovement
{
[Tooltip("How far to predict the distance ahead of the target. Lower values indicate less distance should be predicated")]
public SharedFloat targetDistPrediction = 20;
[Tooltip("Multiplier for predicting the look ahead distance")]
public SharedFloat targetDistPredictionMult = 20;
[Tooltip("The GameObject that the agent is pursuing")]
public SharedGameObject target;
// The position of the target at the last frame
private Vector3 targetPosition;
public override void OnStart()
{
base.OnStart();
targetPosition = target.Value.transform.position;
SetDestination(Target());
}
// Pursue the destination. Return success once the agent has reached the destination.
// Return running if the agent hasn't reached the destination yet
public override TaskStatus OnUpdate()
{
if (HasArrived()) {
return TaskStatus.Success;
}
// Target will return the predicated position
SetDestination(Target());
return TaskStatus.Running;
}
// Predict the position of the target
private Vector3 Target()
{
// Calculate the current distance to the target and the current speed
var distance = (target.Value.transform.position - transform.position).magnitude;
var speed = Velocity().magnitude;
float futurePrediction = 0;
// Set the future prediction to max prediction if the speed is too small to give an accurate prediction
if (speed <= distance / targetDistPrediction.Value) {
futurePrediction = targetDistPrediction.Value;
} else {
futurePrediction = (distance / speed) * targetDistPredictionMult.Value; // the prediction should be accurate enough
}
// Predict the future by taking the velocity of the target and multiply it by the future prediction
var prevTargetPosition = targetPosition;
targetPosition = target.Value.transform.position;
return targetPosition + (targetPosition - prevTargetPosition) * futurePrediction;
}
// Reset the public variables
public override void OnReset()
{
base.OnReset();
targetDistPrediction = 20;
targetDistPredictionMult = 20;
target = null;
}
}
}