SpatialPartition.cs

SpatialPartition.cs

using Hammerwerx.Framework.Game;
using Microsoft.Xna.Framework;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace Hammerwerx.Framework.Runtime {
    public sealed class SpatialPartition {

        private int _cellWidth;

        private int _cellHeight;

        private int _areaWidth;

        private int _areaHeight;

        private SpatialPartitionCell[,] _cells;

        public SpatialPartition(int cellWidth, int cellHeight, int areaWidth, int areaHeight) {

            _cellWidth = cellWidth;

            _cellHeight = cellHeight;

            _areaWidth = areaWidth;

            _areaHeight = areaHeight;

            int xCells = _areaWidth / _cellWidth;

            int yCells = _areaHeight / _cellHeight;

            _cells = new SpatialPartitionCell[xCells,yCells];

            for (int y = 0; y < yCells; y++) {
                for (int x = 0; x < xCells; x++) {
                    _cells[x, y] = new SpatialPartitionCell(x * _cellWidth, y * _cellHeight, _cellWidth, _cellHeight);
                }
            }
        }

        public void OnObjectMove(GameObject gameObject, Vector2 newPosition, Vector2 oldPosition) {

            Vector2 newCellPosition = new Vector2((int)(newPosition.X / _cellWidth), (int)(newPosition.Y / _cellHeight));

            Vector2 oldCellPosition = new Vector2((int)(oldPosition.X / _cellWidth), (int)(oldPosition.Y / _cellHeight));

            if (newCellPosition == oldCellPosition) {
                return;
            }

            SpatialPartitionCell newCell = _cells[(int)newCellPosition.X, (int)newCellPosition.Y];

            SpatialPartitionCell oldCell = _cells[(int)oldCellPosition.X, (int)oldCellPosition.Y];

            if (oldCell.Objects.Contains(gameObject)) {
                oldCell.Objects.RemoveAt(oldCell.Objects.IndexOf(gameObject));
            }

            newCell.Objects.Add(gameObject);

            Debug.Print("GameObject Moved From Cell {0} to Cell {1}", oldCellPosition.ToString(), newCellPosition.ToString());
        }

    }
}