【Unity】Object starts to chase the player approaching
Overview
There is a sample the Cube Object starts to chase the player who goes in a certain area around it.
Environment
Unity 2020 1.1f1
Windows10
Picture of implementation
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Step1 : Set the player
Ethan from the Standard Assets can be used as a human object. Flowwing article explains how to set Ethan and move him.
After place Ethan on Terrian, set the Tag in inspector “Player”.
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Adding rigidbody and capusule collider is needed.
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Step:2 Cube Object chasing player
Next, Set 3D Object Cube.
GameObject > 3D Object Cube
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Adding Character Controller and Sphere Collider to the Cube Object.
Character Controller is useful to moving Cube. The parameters as Default is OK.
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Shpere Collider can be used to detect Player is in certain area. Is Trigger should be checked.
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Step : 3 Script
Following script can realize Cube to chase player when he goes into cube area. Please attach this script.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Approach : MonoBehaviour
{
CharacterController Controller;
Transform Target;
GameObject Player;
[SerializeField]
float MoveSpeed = 2.0f;
int DetecDist = 8;
bool InArea = false;
// Use this for initialization
void Start()
{
// Get GameObject of Player by Tag
Player = GameObject.FindWithTag("Player");
Target = Player.transform;
Controller = GetComponent<CharacterController>();
}
// Update is called once per frame
void Update()
{
if (InArea)
{
// Look at Player
this.transform.LookAt(Target.transform);
// Getting direction from Cube object to Player
Vector3 direction = Target.position - this.transform.position;
direction = direction.normalized;
// Velocity toward Player
Vector3 velocity = direction * MoveSpeed;
// Making y velocity 0 to avoid cube from floating toward y axis
velocity.y = 0.0f;
// Move cube
Controller.Move(velocity * Time.deltaTime);
}
//Calculation of distance between the target object and this object
Vector3 Apos = this.transform.position;
Vector3 Bpos = Target.transform.position;
float distance = Vector3.Distance(Apos, Bpos);
// when distance between cube and player, cube stops tracing.
if (distance > DetecDist)
{
InArea = false;
}
}
// Player gets inside area of cube.
private void OnTriggerEnter(Collider other)
{
InArea = true;
}
}
Step : 4 Test
Please start game and check of them. You may see the pictures like gif animation at top of this page.