private void addTrees(double x, double y) {
		for(int i = 0; i < 500; i++) {
			double tx = x + random.nextGaussian() * 20;
			double ty = y + random.nextGaussian() * 20;
			
			Tree t = new Tree(tx,ty);
			
			if(isEmpty(t)) {
				entities.add(t);
			} else {
				t = null;
			}
		}
	}