Move camera relative to where you're facing

Questions & Answers
1

Most questions want to rotate an object around an axis. But I need to rotate all three axis accordingly around to the rotation of the camera. This is due to the fact I want to mimic most first person shooters: if you press the key to go forward, you go forward relative to where you’re facing not the axis. For example, if I turn my camera to the left 90 degrees and I press the forward button (up arrow), the camera moves forward… as if it didn’t turn at all.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CameraController : MonoBehaviour {

    public float speed;
    public GameObject projectile;
    public GameObject hit_object;

	// Use this for initialization
	void Start () {
		
	}
	
	// Update is called once per frame
	void Update () {
        if (Input.GetKey(KeyCode.RightArrow))
        {
            transform.localPosition += Vector3.right * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            transform.position += Vector3.left * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.DownArrow))
        {
            transform.position += Vector3.back * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.UpArrow))
        {
            transform.position += Vector3.forward * Time.deltaTime * speed;
        }

        if (Input.GetKeyDown(KeyCode.F))
        {
            GameObject bullet = Instantiate(projectile, transform.position, transform.rotation) as GameObject;
            bullet.GetComponent<Rigidbody>().AddRelativeForce(new Vector3(0, 0, 2000));
        }

        if (Input.GetKeyDown(KeyCode.E))
        {
            var pos_x = transform.position.x + Random.Range(-500F, 500F);
            var pos_z = transform.position.z + Random.Range(-500F, 500F);
            Instantiate(hit_object, new Vector3(pos_x, 400, transform.position.z + pos_z), Quaternion.identity);
        }

        transform.Rotate(0f, Input.GetAxis("Horizontal") * speed * Time.deltaTime, 0f, Space.World);
        transform.Rotate(-Input.GetAxis("Vertical") * speed * Time.deltaTime, 0f, 0f, Space.Self);
    }
}

97641-capture.png

In the above snippet, the camera is facing in the direction of the red arrow and thus expect it to move forward in that direction. Instead, it moves according the y-axis (blue arrow). How do I fix this problem?

2

Vector3.forward moves your object in z = 0 direction, that’s wrong script line.
You want to move (direction.position - transform.position)
Reference

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CameraController : MonoBehaviour {

	public float speed;
	public GameObject projectile;
	public GameObject hit_object;
	private Vector3 moveDirection = Vector3.zero;
	public Vector3 movementMultiplier;
	// Use this for initialization
	void Start () {

	}

	// Update is called once per frame
	void Update () {
		moveDirection = new Vector3(movementMultiplier.x, movementMultiplier.y, movementMultiplier.z);
		moveDirection = transform.TransformDirection(moveDirection);
		moveDirection *= speed;
		if (Input.GetKey(KeyCode.RightArrow))
		{
			movementMultiplier.x = 1;
			movementMultiplier.z = 0;
			transform.position += moveDirection * Time.deltaTime;
		}
		if (Input.GetKey(KeyCode.LeftArrow))
		{
			movementMultiplier.x = -1;
			movementMultiplier.z = 0;
			transform.position += moveDirection * Time.deltaTime;
		}
		if (Input.GetKey(KeyCode.DownArrow))
		{
			movementMultiplier.x = 0;
			movementMultiplier.z = -1;
			transform.position += moveDirection * Time.deltaTime;
		}
		if (Input.GetKey(KeyCode.UpArrow))
		{
			movementMultiplier.x = 0;
			movementMultiplier.z = 1;
			transform.position += moveDirection * Time.deltaTime;
		}

		if (Input.GetKeyDown(KeyCode.F))
		{
			GameObject bullet = Instantiate(projectile, transform.position, transform.rotation) as GameObject;
			bullet.GetComponent<Rigidbody>().AddRelativeForce(new Vector3(0, 0, 2000));
		}

		if (Input.GetKeyDown(KeyCode.E))
		{
			var pos_x = transform.position.x + Random.Range(-500F, 500F);
			var pos_z = transform.position.z + Random.Range(-500F, 500F);
			Instantiate(hit_object, new Vector3(pos_x, 400, transform.position.z + pos_z), Quaternion.identity);
		}
	}
}
3

Now, I have solved my solution by using transform.right and transform.forward instead of Vector3. The relevant part of the code now looks likes this:

if (Input.GetKey(KeyCode.RightArrow))
        {[link text][1]
            transform.localPosition += transform.right * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            transform.position += -transform.right * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.DownArrow))
        {
            transform.position += -transform.forward * Time.deltaTime * speed;
        }
        if (Input.GetKey(KeyCode.UpArrow))
        {
            transform.position += transform.forward * Time.deltaTime * speed;
        }

I have gotten my solution here as the answerer explained the difference of using transform and Vector3.