Character Rotating on Z Axis when not supposed too

Hello all,
I have an issue where when moving my player and rotating he seems to be rotating along the Z axis as well when it should be staying at 0. My end goal is basically to make a free cam where the player can fly around the game.

Here is all of my movement code, and the Hierarchy tree in which I have all of my objects

Sample Scene

>Directional Light
> Ground (Cube with scale at 35, 1, 35)
> Player

>Camera (With the code below attached)​

Code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class FreeCam : MonoBehaviour {
6.  
7.     public Camera playerCamera;
8.  
9.     float mouseInputX;
10.     float mouseInputY;
11.     private bool isPanning;
12.  
13.     //Control Modifiers
14.     public float flySpeed;
15.     public float panSpeed;
16.     public float lookSens;
17.  
18.     // Start is called before the first frame update
19.     void Start() {
20.  
21.     }
22.  
23.     // Update is called once per frame
24.     void Update() {
25.  
26.         //Right Movement
27.         if (Input.GetKey(KeyCode.D) || Input.GetKey(KeyCode.RightArrow)) {
28.             transform.Translate(flySpeed * Time.deltaTime, 0, 0);
29.         }
30.  
31.         //Left Movement
32.         if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow)) {
33.             transform.Translate(-flySpeed * Time.deltaTime, 0, 0);
34.         }
35.  
36.         //Forward Movement
37.         if (Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.UpArrow)) {
38.             transform.Translate(0, 0, flySpeed * Time.deltaTime);
39.         }
40.  
41.         //Backwards Movement
42.         if (Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.DownArrow)) {
43.             transform.Translate(0, 0, -flySpeed * Time.deltaTime);
44.         }//END OF MOVEMENT
45.  
46.         //Mouse Panning
47.         if (Input.GetMouseButton(1)) { //If the right mouse button is held
48.             mouseInputX = Input.GetAxis("Mouse X");
49.             mouseInputY = Input.GetAxis("Mouse Y");
50.             transform.Rotate(-mouseInputY * lookSens, mouseInputX * lookSens, 0);
51.         }//END IF STATEMENT
52.     }
53. }
54.  

I am very new to Unity, and any help would be greatly appriciated!

 

Is the player using a rigidbody component? It might be colliding with something and that could cause the unexpected rotation.

By the way, you seem to have mixed up the X and Y inputs in the mouse panning section.

Also instead of checking with an if for each direction I would recommend using unity's built-in input system, that way you wouldn't have to use 4 if-s thus making your code more efficient and easy to read. The unity documentation actually has a code snippet for a simple movement system.

https://docs.unity3d.com/ScriptReference/Input.GetAxis.html

 

The problem is that Z rotation can be "created" out of Y and X rotations. Imagine this: You rotate an object 90 degrees upwards, so it's looking at the ceiling. Then rotate it 90 degrees to its right. It's now laying on its side and looking at the right wall, even though we never rotated it on its side. It just happened as a result of the other two rotations.

You can solve this like so:

Code (csharp):

1. private float totalXRot = 0f;
2. private float totalYRot = 0f;
3.  
4. void Update() {
5. ...
6. totalXRot += Input.GetAxis("Mouse X") * lookSens;
7. totalYRot += Input.GetAxis("Mouse Y") * lookSens;
8. transform.rotation = Quaternion.Euler(totalYRot, totalXRot, 0f);
9. }

Basically, store your own X and Y rotation numbers, and overwrite the transform's rotation every frame.

 

This was amazing! Thank you so much for such a great explanation and telling me how to fix it, it worked beautifully. Now to do some study on Quaternions so I can understand this...