Question Repeatedly Rotate tile in tilemap not working

Hello all,
I am trying to make a simple game taking inspiration from factorio, and was trying to add rotateable machines (like in factorio). What I was trying to achieve was that whenever you press 'R' whilst hovering over a tile, said tile rotates by 90 degree increments (e.g. 1 press = 90 degrees, 2 = 180 etc.). I quickly ecountered the following problem: I can rotate it once, if I try to do so again, it rotates by 1 degree or so and all further presses seem to have no effect whatsoever.

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.Tilemaps;
3.  
4. public class TileManager : MonoBehaviour
5. {
6.     Tilemap tilemap;
7.     Vector3Int tilemapPos;
8.  
9.     // There is some other code here, for example drawing tiles, selecting which one to draw etc. just assumed it to be irrelevant
10.  
11.     if (Input.GetKeyDown(KeyCode.R))
12.     {
13.         tilemapPos = tilemap.WorldToCell(Camera.main.ScreenToWorldPoint(Input.mousePosition));
14.         float rot = tilemap.GetTransformMatrix(tilemapPos).rotation.z;
15.         Matrix4x4 matrix = Matrix4x4.TRS(Vector3.zero, Quaternion.Euler(0f, 0f, rot + 90f), Vector3.one);
16.         tilemap.SetTransformMatrix(tilemapPos, matrix);
17.         }

I am assuming this has something to do with quaternions? I searched the internet and couldn't find a solution for this, so decided to ask it here. Any simple explanation of why this isn't working is also greatly appreciated.

EDIT: I am aware that storing a variable for each tile's rotation is a valid solution, however the board begins at a smaller size, and I plan for it to get bigger, meaning this solution wouldn't work.

EDIT EDIT: Actually this will work, I'm just an idiot. You can use a 2d array, and when the board gets bigger, add some elements at the start and end of both the big array and all subarrays.

Thanks in advance!

 

Thank you! I implemented the first solution, worked perfectly. Much more compact than 2d arrays (and simpler too!) I don't know why I didn't see euler angles as it's the second auto complete option.
Thanks again!