LibGDX : Detecting where a Ray hits a 3D object

问题

I am building a 3D game in LibGDX, I have used the following code to work out if I touch a object, but how do I find out at what point it collides. I am not using Bullet as I want to make a HTML5 port

    public int getObject (int screenX, int screenY) {

        int result = -1;
        float distance = -1;

        Ray ray = camera.getPickRay(screenX, screenY);
        Vector3 pos = new Vector3(camera.position);

        for (int i = 0; i < boxInstance.size; i++) {

            GameObject instance = boxInstance.get(i);
            instance.transform.getTranslation(pos);

            float dist2 = ray.origin.dst2(pos);
            if (distance >= 0f && dist2 > distance) continue;

            if (Intersector.intersectRayBoundsFast(ray, pos, instance.dimensions)) {
                result = i;
                distance = dist2;

                Vector3 v = new Vector3();
                if (Intersector.intersectRayBounds(ray, instance.bounds, v))
                {
                    boxInstance.get(result).materials.get(0).set(ColorAttribute.createDiffuse(Color.RED));
                }
            }
        }

        if (result > -1)
        {

            //boxInstance.removeIndex(result);
        }

        return 1;
    };

The reason I need this is if I touch a large plane, I want to be able to plane a object where I touch.

Update I found intersectRayBounds which should do what I want but it never fires

Here is my GameObject class. Maybe my BoundingBox is wrong?

public class GameObject extends ModelInstance {
    public final Vector3 center = new Vector3();
    public final Vector3 dimensions = new Vector3();
    public static BoundingBox bounds = new BoundingBox();

    public GameObject (Model model, float x, float y, float z) {
        super(model, x,y,z);
        calculateBoundingBox(bounds);
        bounds.getCenter(center);
        bounds.getDimensions(dimensions);
    }
}

回答1:

I am not sure why this is the fix but it appears you have to compute the Bounding box everytime. See code below.

    public int getObject (int screenX, int screenY) {

        int result = -1;
        float distance = -1;

        Ray ray = camera.getPickRay(screenX, screenY);
        Vector3 pos = new Vector3(camera.position);

        for (int i = 0; i < boxInstance.size; i++) {

            GameObject instance = boxInstance.get(i);
            instance.transform.getTranslation(pos);
            instance.updateBox();

            float dist2 = ray.origin.dst2(pos);
            if (distance >= 0f && dist2 > distance) continue;


            Vector3 v = new Vector3();
            if (Intersector.intersectRayBounds(ray, instance.bounds, v))
            {
                result = i;
                distance = dist2;
                Gdx.app.log("MyTag 2", "x " + v.x + " z " + v.z);

            }

        }

        if (result > -1)
        {
            boxInstance.get(result).materials.get(0).set(ColorAttribute.createDiffuse(Color.RED));
        }

        return 1;
    };


public class GameObject extends ModelInstance {
    public final Vector3 center = new Vector3();
    public final Vector3 dimensions = new Vector3();
    public static BoundingBox bounds = new BoundingBox();
    private float x,y,z;


    public GameObject (Model model, float x, float y, float z) {
        super(model, x, y, z);
        this.x = x;
        this.y = y;
        this.z = z;
        updateBox();
    }

    public void updateBox()
    {
        calculateBoundingBox(bounds);
        bounds.getCenter(center);
        bounds.getDimensions(dimensions);
        bounds.set(bounds.min.add(x,y,z), bounds.max.add(x,y,z));

        Gdx.app.log("MyTag 2", "x " + bounds.min + " z " + bounds.max );
    }

}

来源：https://stackoverflow.com/questions/31805868/libgdx-detecting-where-a-ray-hits-a-3d-object