Top-down 2D motion in 3D game

Question

I'm creating a 3D top-down shooter for my course's final project and am having trouble getting the player movement to work properly. I want the character to behave as it would in an 2D top-down shooter, where they can move in the cardinal directions relative to the camera (up, down, left, right) plus a combination of these (up-left, down-right, etc.). I have the movement operating normally, but the player should also instantly rotate into the direction they're moving, somewhat like this video: https://www.youtube.com/watch?v=1IcOoVUGafc&t=60s

I'm able to get the rotation working, but it's not instantaneous. I've been led to Transform.LookAt function, but I don't think I understand how it works. When I use it, I get wacky behavior. Here's the closest I've gotten.

  horizontalInput = Input.GetAxis("Horizontal");
  verticalInput = Input.GetAxis("Vertical");

  transform.LookAt(Vector3.forward * verticalInput);

  transform.Translate(Vector3.forward * Time.deltaTime * playerSpeed * verticalInput);
  transform.Translate(Vector3.right * Time.deltaTime * playerSpeed * horizontalInput);

Any help is appreciated, especially if it's to a video that helps explain these concepts to dummies like me a bit better.

Answer 1

Hey @raginghobo32907 I just finished the Haunted Jaunt tutorial on Unity Learn. The movement you're describing is explained on there. Here's the relevant snippet for you:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class SimpleMove : MonoBehaviour
 {
 
     public float moveSpeed = 1f;
     public float turnSpeed = 20f;
 
 
     Rigidbody m_Rigidbody;
     Vector3 m_Movement;
     Quaternion m_Rotation = Quaternion.identity;
 
 
     void Start()
     {
         m_Rigidbody = GetComponent<Rigidbody>();
     }
 
 
     void FixedUpdate()
     {
         float horizontal = Input.GetAxis("Horizontal");
         float vertical = Input.GetAxis("Vertical");
 
         m_Movement.Set(horizontal, 0f, vertical);
         m_Movement.Normalize();
 
         bool hasHorizontalInput = !Mathf.Approximately(horizontal, 0f); // Sets the bool to true if 'horizontal' input is approx 0
         bool hasVerticalInput = !Mathf.Approximately(vertical, 0f);
         bool isWalking = hasHorizontalInput || hasVerticalInput;
         
 
         Vector3 desiredForward = Vector3.RotateTowards(transform.forward, m_Movement, turnSpeed * Time.deltaTime, 0f);
         m_Rotation = Quaternion.LookRotation(desiredForward);
 
         m_Rigidbody.MovePosition(m_Rigidbody.position + m_Movement * moveSpeed * Time.deltaTime);
         m_Rigidbody.MoveRotation(m_Rotation);
     }
 }

Top-down 2D motion in 3D game

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