protected void clear() {
		if (complete) {
			throw new ErrorException("You can't clear a GPolygon that has been "
			                         + "marked as complete.");
		}
		vertexList = new ArrayList();
		cx = 0;
		cy = 0;
		rotation = 0;
		xScale = 1.0;
		yScale = 1.0;
		cacheValid = false;
	}