GodotComponentTest/scenes/StreamContainer.cs

using Godot;
using System.Collections.Generic;
using System.Linq;

//using Dictionary = Godot.Collections.Dictionary;

public class StreamContainer : Spatial
{
    // scene nodes
    private MeshInstance _bounds;
    private Spatial _activeTiles;

    // resources
    private PackedScene _hexTileScene = GD.Load<PackedScene>("res://scenes/HexTile3D.tscn");

    // exports
    [Export] public Vector2 Dimensions = new Vector2(8, 4);

    // other members
    private Rect2 _worldRect;
    private Rect2 _currentOffsetCoordRect;
    private Rect2 _oldOffsetCoordRect;
    private HexGrid _hexGrid;

    private Dictionary<Vector2, Spatial> _coordToTile = new Dictionary<Vector2, Spatial>();
    public List<Vector2> RemovedCoords = new List<Vector2>();
    public List<Vector2> AddedCoords = new List<Vector2>();

    public Rect2 CurrentOffsetCoordRect
    {
        get { return _currentOffsetCoordRect; }
    }

    // Called when the node enters the scene tree for the first time.
    public override void _Ready()
    {
        _bounds = GetNode<MeshInstance>("Bounds");
        _activeTiles = GetNode<Spatial>("ActiveTiles");

        _hexGrid = new HexGrid();

        Transform boundsTransform = Transform.Identity;
        boundsTransform = boundsTransform.Scaled(new Vector3(Dimensions.x, 1, Dimensions.y));
        _bounds.Transform = boundsTransform;

        Spatial hexTile3d = (Spatial)_hexTileScene.Instance();
        AddChild(hexTile3d);
    }


    public void UpdateRects(Vector2 centerPlane)
    {
        _oldOffsetCoordRect = _currentOffsetCoordRect;

        Vector2 bottomLeftCoord = centerPlane - new Vector2(Dimensions.x / 2, Dimensions.y / 2);
        Vector2 topRightCoord = centerPlane + new Vector2(Dimensions.x / 2, Dimensions.y / 2);

        _worldRect = new Rect2(bottomLeftCoord, Dimensions);
//        GD.Print("World rect now: " + _worldRect.ToString() + " center: " + _worldRect.GetCenter());

        // y axis needs to be inverted as HexGrid's offset coordinates use the opposite axis direction
        HexCell bottomLeftCell = _hexGrid.GetHexAt(new Vector2(bottomLeftCoord.x, topRightCoord.y));
        HexCell topRightCell = _hexGrid.GetHexAt(new Vector2(topRightCoord.x, bottomLeftCoord.y));
        _currentOffsetCoordRect = new Rect2(bottomLeftCell.OffsetCoords,
            topRightCell.OffsetCoords - bottomLeftCell.OffsetCoords + Vector2.One);
//        GD.Print("Offset rect now: " + _currentOffsetCoordRect.ToString() + " center: " +
//                 _currentOffsetCoordRect.GetCenter());

        Transform boundsTransform = _bounds.Transform;
        boundsTransform.origin.x = centerPlane.x;
        boundsTransform.origin.z = centerPlane.y;
        _bounds.Transform = boundsTransform;

//        GD.Print("Bounds Transform: " + boundsTransform.ToString());
//        GD.Print("Bounds Global   : " + _bounds.GlobalTransform.ToString());

        if (!_currentOffsetCoordRect.Equals(_oldOffsetCoordRect))
        {
            UpdateTileCache();
        }
    }


    public void UpdateTileCache()
    {
        RemovedCoords.Clear();
        AddedCoords.Clear();
    
        Rect2 expandedRect = _currentOffsetCoordRect.Merge(_oldOffsetCoordRect);

        foreach (int coord_x in Enumerable.Range(Mathf.FloorToInt(expandedRect.Position.x), Mathf.CeilToInt(expandedRect.Size.x)))
        {
            foreach (int coord_y in Enumerable.Range(Mathf.FloorToInt(expandedRect.Position.y),
                         Mathf.CeilToInt(expandedRect.Size.y)))
            {
                Vector2 coord = new Vector2(coord_x, coord_y);
                bool isInCurrent = _currentOffsetCoordRect.HasPoint(coord);
                bool isInOld = _oldOffsetCoordRect.HasPoint(coord);

                if (isInCurrent && !isInOld)
                {
                    AddedCoords.Add(coord);
                    GetTile3dAt(coord);
                }
                else if (isInOld && !isInCurrent)
                {
                    RemovedCoords.Add(coord);
                    if (_coordToTile.Keys.Contains(coord))
                    {
                        Spatial tile3d = _coordToTile[coord];
                        _activeTiles.RemoveChild(tile3d);
                        tile3d.QueueFree();
                    }
                }
            }
        }
    }


    public Spatial GetTile3dAt(Vector2 offsetCoords)
    {
        if (!_coordToTile.Keys.Contains(offsetCoords))
        {
            Spatial tile3d = (Spatial)_hexTileScene.Instance();
            HexCell cell = new HexCell();
            cell.OffsetCoords = offsetCoords;
            Vector2 cellPlaneCoords = _hexGrid.GetHexCenter(cell);
            Transform tile3dTransform = Transform.Identity;
            tile3dTransform.origin = new Vector3(cellPlaneCoords.x, GD.Randf() * 0.1f, cellPlaneCoords.y);
            tile3d.Transform = tile3dTransform;
            _activeTiles.AddChild(tile3d);
            _coordToTile[offsetCoords] = tile3d;
        }

        return _coordToTile[offsetCoords];
    }

    public void SetCenterTile(HexCell cell)
    {
        UpdateRects(_hexGrid.GetHexCenter(cell));
    }
}