GodotComponentTest/HexGrid.cs

using System;
using Godot;

public class HexGrid : Resource
{
    private Vector2 _baseHexSize = new Vector2(1, Mathf.Sqrt(3) / 2);
    private Vector2 _hexSize = new Vector2(1, Mathf.Sqrt(3) / 2);
    private Vector2 _hexScale = new Vector2(1, 1);
    private Godot.Transform2D _hexTransform;
    private Godot.Transform2D _hexTransformInv;

    public Vector2 HexSize
    {
        get { return _hexSize; }
    }

    public Vector2 HexScale
    {
        get { return _hexScale; }
        set
        {
            _hexScale = value;
            _hexSize = _baseHexSize * _hexScale;
            _hexTransform = new Transform2D(
                new Vector2(_hexSize.x * 3 / 4, -_hexSize.y / 2),
                new Vector2(0, -_hexSize.y),
                new Vector2(0, 0)
            );

            _hexTransformInv = _hexTransform.AffineInverse();
        }
    }

    public HexGrid()
    {
        HexScale = new Vector2(1, 1);
    }

    public Vector2 GetHexCenter(HexCell cell)
    {
        return _hexTransform * cell.AxialCoords;
    }

    public Vector2 GetHexCenterFromOffset(Vector2 offsetCoord)
    {
        HexCell cell = new HexCell();
        cell.OffsetCoords = offsetCoord;
        return GetHexCenter(cell);
    }

    public HexCell GetHexAtOffset(Vector2 offsetCoord)
    {
        HexCell cell = new HexCell();
        cell.OffsetCoords = offsetCoord;
        return cell;
    }

    public HexCell GetHexAt(Vector2 planeCoord)
    {
        HexCell result = new HexCell(_hexTransformInv * planeCoord);
        return result;
    }
}