Debug grid for libgdx

The java Q&A column brought by php editor Zimo will discuss the debugging grid function in the libgdx game engine today. libgdx is a powerful cross-platform game development framework. Its debugging grid function can help developers better debug game scenes and improve development efficiency. This article will introduce in detail how to enable and use the debug grid in libgdx to help developers better utilize this feature for game development.

Question content

Can I somehow draw a 3d grid in my libgdx application so that I can zoom in and out of the grid to see what's going on with my application What? For example, I tried to create a simple sphere that should be in the middle of the screen, but it's not and it's squished or something.

I want to know where my camera is and what the camera's perspective is, all within the scene. Here's the code because stackoverflow asked for it.

@Override
    public void create() {
        modelBatch = new ModelBatch();
        environment = new Environment();
        environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f));
        environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, 10f, 10f, 20f));

        cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
        cam.position.set(150f, -9f, 200f);
        cam.lookAt(0, 0, 0);
        cam.near = 1f;
        cam.far = 300f;
        cam.update();


        ModelBuilder modelBuilder = new ModelBuilder();
        model = modelBuilder.createSphere(120f, 120f, 120, 32, 32,
                new Material(ColorAttribute.createDiffuse(Color.GREEN)),
                VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal);
        instance = new ModelInstance(model);
        instance.transform.set(new Vector3(100, 100, 0), new Quaternion());
    }

Can I do this?

Solution

After some searching I found this amazing list of libgdx examples, including grids with axes:

private void createaxes() {
        final float grid_min = -viewportwidth;
        final float grid_max = viewportwidth;
        final float grid_step = viewportwidth / 10;

        modelbuilder modelbuilder = new modelbuilder();
        modelbuilder.begin();
        meshpartbuilder builder = modelbuilder.part("grid", gl20.gl_lines, usage.position | usage.colorunpacked, new material());
        builder.setcolor(color.light_gray);
        for (float t = grid_min; t <= grid_max; t += grid_step) {
            builder.line(t, 0, grid_min, t, 0, grid_max);
            builder.line(grid_min, 0, t, grid_max, 0, t);
        }
        builder = modelbuilder.part("axes", gl20.gl_lines, usage.position | usage.colorunpacked, new material());
        builder.setcolor(color.red);
        builder.line(0, 0, 0, 100, 0, 0);
        builder.setcolor(color.green);
        builder.line(0, 0, 0, 0, 100, 0);
        builder.setcolor(color.blue);
        builder.line(0, 0, 0, 0, 0, 100);
        model axesmodel = modelbuilder.end();
        models.add(axesmodel);
        modelinstance instance = new modelinstance(axesmodel);
        instances.add(instance);
    }

Here is an example of how to use it: https://www.php.cn/link/2d0098b9484a341987c5b11e51d7b79f

You can use " createlinegrid" to create a grid that extends in x-z (unless you rotate it) > plane. For example:

grid = modelbuilder.createlinegrid(
   32, 32, 10.0f, 10.0f, 
    new material(colorattribute.creatediffuse(color.red)), 
    vertexattributes.usage.position | vertexattributes.usage.normal);

gridinstance = new modelinstance(grid);

Where

grid

is model, gridinstance is modelinstance. Then you just include the render call into your modelbatch:

modelBatch.render(gridInstance);

Doing this on your code produces the following rendering:

You can customize the number of grid lines and their spacing to suit your needs.

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