MyGdxGame.java

public class MyGdxGame extends ApplicationAdapter {

    private ShaderProgram shaderProgram;
    private Mesh mesh;


    @Override
	public void create () {
        texture = new Texture(Gdx.files.internal("texture_default.jpg"));

        batch = new SpriteBatch();
        sprite = new Sprite(texture);

		FileHandle f = Gdx.files.internal("f_shader.glsl");
        FileHandle v = Gdx.files.internal("v_shader.glsl");

		shaderProgram = new ShaderProgram(v, f);
        ShaderProgram.pedantic = false;

        mesh = new Mesh(true, 4, 6, VertexAttribute.Position());//, VertexAttribute.TexCoords(0));

        mesh.setVertices(new float[]
                      {-0.5f, -0.5f, 0,
                        0.5f, -0.5f, 0,
                        0.5f, 0.5f,  0,
                        -0.5f, 0.5f, 0, });
        mesh.setIndices(new short[]{0, 1, 2, 2, 3, 0});

    if(!shaderProgram.isCompiled()) {
        String log = shaderProgram.getLog();
        Gdx.app.log("Log", log);
    }
}

    @Override
    public void render () {

        Matrix4 o = new Matrix4();
        o.setToOrtho2D(0f, 0f, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());


        shaderProgram.begin();

        shaderProgram.setUniformMatrix("u_projViewTrans", cam.combined);
        shaderProgram.end();

        mesh.bind(shaderProgram);
        mesh.render(shaderProgram, GL20.GL_TRIANGLES);


    }
}