Generates an isometric aligned polygon collider in a box shape

IsoAlignedBoxCollider2D.cs

using System.Collections.Generic;
using Sirenix.OdinInspector;
using UnityEngine;

public enum IsoAlignmentOption {
    NorthSouth,
    EastWest,
    NorthEastSouthWest,
    NorthWestSouthEast
}

[RequireComponent(typeof(PolygonCollider2D))]
public class IsoAlignedBoxCollider2D : MonoBehaviour {
    [OnValueChanged("UpdateCollider")]
    public int width, height;
    [OnValueChanged("UpdateCollider")]
    public IsoAlignmentOption alignment;

    protected PolygonCollider2D _collider;
    protected Vector2[] _points = new Vector2[4];
    
    /// <summary>
    /// Set this to match your pixel grid size.
    /// </summary>
    static readonly float GridSize = 1 / 32f;

    /// <summary>
    /// Unlike the traditional isometric projection of 30°, or the 3D modeler's
    /// isometric of 27.368°, in pixel art the ideal projection creates exactly
    /// two pixels of width (run) for every pixel of height (rise).
    ///
    /// To find an angle from the rise and the run, use atan(rise, run). That
    /// gives us atan(1 / 2) = 26.565°. That is our *pixel-perfect* isometric
    /// angle.
    /// </summary>
    static readonly float IsometricAngle = Mathf.Rad2Deg * Mathf.Atan(1f / 2f);

    static readonly Dictionary<IsoAlignmentOption, Matrix4x4> RotationMatrices =
        new Dictionary<IsoAlignmentOption, Matrix4x4> {
            { IsoAlignmentOption.NorthSouth, Matrix4x4.Rotate(Quaternion.Euler(0, 0, 0)) },
            { IsoAlignmentOption.EastWest, Matrix4x4.Rotate(Quaternion.Euler(0, 0, 90)) },
            { IsoAlignmentOption.NorthEastSouthWest, Matrix4x4.Rotate(Quaternion.Euler(0, 0, IsometricAngle)) },
            { IsoAlignmentOption.NorthWestSouthEast, Matrix4x4.Rotate(Quaternion.Euler(0, 0, -IsometricAngle)) }
        };

    [OnInspectorInit]
    protected void SetColliderForEditor() {
        _collider = GetComponent<PolygonCollider2D>();
    }

    protected void Start() {
        _collider = GetComponent<PolygonCollider2D>();
        UpdateCollider();
    }

    protected void UpdateCollider() {
        var halfSize = new Vector2(width, height) * GridSize / 2f;

        _points[0] = new Vector2(-halfSize.x, halfSize.y);
        _points[1] = new Vector2(halfSize.x, halfSize.y);
        _points[2] = new Vector2(halfSize.x, -halfSize.y);
        _points[3] = new Vector2(-halfSize.x, -halfSize.y);

        for (var i = 0; i < _points.Length; i++) {
            _points[i] = RotationMatrices[alignment].MultiplyPoint(_points[i]);
        }

        _collider.points = _points;
    }
}