public void initialize(String rootDirPath)
			throws ParserConfigurationException, SAXException, IOException {
		if (rigidBodiesBranchGroup.numChildren() != 0
				|| lightsBranchGroup.numChildren() != 0
				|| wireframeRigidBodiesBranchGroup.numChildren() != 0) {
			clear();
		}

		assetLibrary.clear();
		assetLibrary.readAllAssets(rootDirPath);

		Document document = ResourceController.readXML(rootDirPath
				+ File.separator + LEVEL_DATA);
		document.getDocumentElement().normalize();

		// Initialize environment variables (gravity)
		initializeEnvironment(document);

		// Initialize rigid bodies
		initializeRigidBodies(document);

		// Initialize lights
		initializeLights(document);
		currentPath = rootDirPath;
	}