3d scene test

public class GameScreen implements Screen {

    public PerspectiveCamera cam;
    public ModelInstance instance;
    public Model model;
    public Environment environment;
    public ModelBatch modelBatch;

    public GameScreen() {

        cam = new PerspectiveCamera(67f, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        cam.position.set(0, 0, 0);
        cam.lookAt(0,0,0);
        cam.near = 0.1f;
        cam.far = 250f;
        cam.update();

        modelBatch = new ModelBatch();

        environment = new Environment();
            environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.7f, 0.7f, 0.7f, 1f));
    }

    @Override
    public void render(float delta) {

         Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
         Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);

         modelBatch.begin(cam);

         Texture tex =  new Texture(Gdx.files.internal("grid.png"), true);
         tex.setFilter(TextureFilter.MipMap, TextureFilter.MipMap);
         modelBatch.render(this.createPlane("front",tex), environment);
         modelBatch.render(this.createPlane("bottom", tex), environment);
         modelBatch.render(this.createPlane("left", tex), environment);
         modelBatch.render(this.createPlane("right", tex), environment);

         modelBatch.end();
    }

    @Override
    public void resize(int width, int height) {
        float aspectRatio = (float) width / (float) height;
        cam = new PerspectiveCamera(67, 2f * aspectRatio, 2f);

    }

    private ModelInstance createPlane(String wall, Texture texture) {

        float z = -3.5f;

            Vector3 _00, _01, _10, _11, norm;

            _00 = new Vector3();
            _01 = new Vector3();
            _10 = new Vector3();
            _11 = new Vector3();
            norm = new Vector3();

            // Wall data
            HashMap<String, ArrayList<Vector3>> wallData = new HashMap<String, ArrayList<Vector3>>();

            // front
            ArrayList<Vector3> front = new ArrayList<Vector3>();
            front.add(new Vector3(1, 1, z));
            front.add(new Vector3(-1, 1, z));
            front.add(new Vector3(-1, -1, z));
            front.add(new Vector3(1, -1, z));

            wallData.put("front", front);

            // bottom
            ArrayList<Vector3> bottom = new ArrayList<Vector3>();
            bottom.add(new Vector3(1, -1, z));
            bottom.add(new Vector3(-1, -1, z));
            bottom.add(new Vector3(-1f, -1, z+2));
            bottom.add(new Vector3(1f, -1, z+2));

            wallData.put("bottom", bottom);

            // left
            ArrayList<Vector3> left = new ArrayList<Vector3>();
            left.add(new Vector3(-1, 1, z));
            left.add(new Vector3(-1, 1, z+2));
            left.add(new Vector3(-1, -1, z+2));
            left.add(new Vector3(-1, -1, z));

            wallData.put("left", left);

            // right
            ArrayList<Vector3> right = new ArrayList<Vector3>();
            right.add(new Vector3(1, 1, z+2));
            right.add(new Vector3(1, 1, z));
            right.add(new Vector3(1, -1, z));
            right.add(new Vector3(1, -1, z+2));

            wallData.put("right", right);

            Material material = new Material();
            texture.setFilter(TextureFilter.Linear, TextureFilter.Nearest);

            TextureAttribute textureAttribute = new TextureAttribute(TextureAttribute.Diffuse, texture);
            material.set(textureAttribute);

            ArrayList<Vector3> vertexData = wallData.get(wall);
            Model model = null;
            ModelBuilder mb = new ModelBuilder();
            mb.begin();

            MeshPartBuilder part = mb.part("rect", GL20.GL_TRIANGLES,  VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates, material);

            _11.set(vertexData.get(0));         // right up
            _01.set(vertexData.get(1));         // left up

            _00.set(vertexData.get(2));         // left bottom
            _10.set(vertexData.get(3));         // right bottom

            norm = new Vector3(0, 0, -1);

            part.rect(_00, _10, _11, _01, norm);
            model = mb.end();

            model.manageDisposable(texture);
            ModelInstance modelInstance = new ModelInstance(model);

            modelInstance.transform.setToTranslation(0, 0, 0);

            return modelInstance;
        }

}