GPS Coordinate Conversion System

public class GPSConverter
{
    private const int ZOOM_LEVEL = 15;
    private const float TILE_SIZE = 100f; // Unity Unit
    
    private Vector2Int _originTile; // 기준점 타일 (강남역)
    
    // GPS → Unity World Position
    public Vector3 GPSToUnity(double lat, double lon)
    {
        // 1. GPS → 타일 좌표
        Vector2Int tile = GPSToTileCoord(lat, lon);
        
        // 2. 타일 좌표 → Unity 좌표
        return TileToUnity(tile);
    }
    
    private Vector2Int GPSToTileCoord(double lat, double lon)
    {
        float n = Mathf.Pow(2, ZOOM_LEVEL);
        
        // Longitude → X (선형 변환)
        int x = (int)((lon + 180.0) / 360.0 * n);
        
        // Latitude → Y (Mercator Projection)
        double latRad = lat * Mathf.Deg2Rad;
        double mercN = Math.Log(Math.Tan(latRad) + 1 / Math.Cos(latRad));
        int y = (int)((1 - mercN / Math.PI) / 2 * n);
        
        return new Vector2Int(x, y);
    }
    
    private Vector3 TileToUnity(Vector2Int tile)
    {
        int deltaX = tile.x - _originTile.x;
        int deltaY = tile.y - _originTile.y;
        
        return new Vector3(
            deltaX * TILE_SIZE,
            0,
            -deltaY * TILE_SIZE
        );
    }
    
    // 3x3 타일 로드 시스템
    public void UpdateTiles(Vector2Int playerTile)
    {
        for (int dx = -1; dx <= 1; dx++) {
            for (int dy = -1; dy <= 1; dy++) {
                Vector2Int tileCoord = new Vector2Int(
                    playerTile.x + dx,
                    playerTile.y + dy
                );
                
                if (!_loadedTiles.ContainsKey(tileCoord)) {
                    StartCoroutine(LoadTileAsync(tileCoord));
                }
            }
        }
        
        UnloadDistantTiles(playerTile);
    }
}