public static void createTree(ResearchScreen rs, ResearchItem root, float x, float y) {
        if(root != null) {
            rs.addItemSlot(x, y, root);
            if(root.researched()) {
                int indx = 0;
                for(ResearchItem i : root.getFollowers()) {
                    createTree(rs, i, x+indx*90, y+90);
                    indx++;
                }
            }
        }
    }