ShaderProgram.loadShader生成NullPointerException（旧帖子的新帖子）

Question

旧帖子：https://stackoverflow.com/questions/29616270/shaderprogram-loadshader-throws-nullpointerexception。

我基本上遇到与以下链接中的人相同的问题：Libgdx着色器设置NullPointerException。然而，我正试图在我的桌面而不是Android虚拟仿真器上启动它。有没有办法在桌面上启用OpenGl ES 2.0？

Exception in thread "main" java.lang.NullPointerException
    at com.badlogic.gdx.graphics.glutils.ShaderProgram.loadShader(ShaderProgram.java:194)
    at com.badlogic.gdx.graphics.glutils.ShaderProgram.compileShaders(ShaderProgram.java:173)
    at com.badlogic.gdx.graphics.glutils.ShaderProgram.<init>(ShaderProgram.java:156)
    at com.badlogic.gdx.graphics.glutils.ImmediateModeRenderer20.createDefaultShader(ImmediateModeRenderer20.java:233)
    at com.badlogic.gdx.graphics.glutils.ImmediateModeRenderer20.<init>(ImmediateModeRenderer20.java:56)
    at com.badlogic.gdx.graphics.glutils.ShapeRenderer.<init>(ShapeRenderer.java:116)
    at com.badlogic.gdx.graphics.glutils.ShapeRenderer.<init>(ShapeRenderer.java:111)
    at com.badlogic.gdx.graphics.glutils.ShapeRenderer.<init>(ShapeRenderer.java:107)
    at View.Maze.<init>(Maze.java:20)
    at com.ratmazesprint.game.RatMazeSprintGame.<init>(RatMazeSprintGame.java:14)
    at com.ratmazesprint.game.desktop.DesktopLauncher.main(DesktopLauncher.java:14)

这是代码崩溃的地方：

SpriteBatch batch;
    ShapeRenderer renderer;

public Maze(){

    --> renderer = new ShapeRenderer();
        cam = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        cam.position.set(Gdx.graphics.getWidth()/2, Gdx.graphics.getHeight()/2, 0);
        batch = new SpriteBatch();
        touchPos = new Vector3();
        position = new Vector2(1, 1); 

        //this.cam = new OrthographicCamera(10, 7);
        //this.cam.update();
        //drawGrid();
        //this.model = model;
        model.addObserver(this);
    }