Rounded object falls through terrain

I have also noticed that if I add rounded physics object at the center point (x, z = 0, 0) of the terrain it also falls through the terrain.
I can share a video if that would help.

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I prefer executable sourcecode to video.

Sorry I can’t. Happens in my editor.

If you can’t reproduce the issue, how could anyone else do so?

The key take away from sgold’s message is that a simple test case makes a big difference.

…and from experience, 9 times out of 10, things will work fine in the simple test case and the issue-reporter has something to look into on their end.

Without a test case, no matter how hard someone looks into it, there will be this nagging thought in the back of their mind “Maybe it’s just a problem with ndebruyn’s editor setup”… which even if untrue will prevent the brain from really considering all solutions.

…and it might be true.

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Thanks @pspeed for your thought on this.
Sometimes it helps to be kind.

I am in the process of setting up a TestCase for this. In my editor adding a terrain and quickly adding a sphere is a few seconds. However setting this up in code will take a bit more time.


At the end of the day, I am just trying to help the Minie library.


Sometimes it helps to be kind.

I love troubleshooting, and I appreciate your help with Minie. If my comments were brusque or rude, I apologize for that.

a simple test case makes a big difference.


Perhaps I am unusually code-oriented (or reluctant to “play 20 questions”). To me, any test case—even a complex one—is more welcome than a video or a verbal description of an issue.

Okay here is a test case that causes the issue. Seems like it has to do with:


Anyways, here is my test case:

public class TerrainTest extends SimpleApplication {

    private BulletAppState bulletAppState;
    private RigidBodyControl landscape;
    private RigidBodyControl ballBody;
    private Geometry ball;
    private TerrainQuad terrain;
    private Material mat_terrain;

    public static void main(String[] args) {
        TerrainTest app = new TerrainTest();

    public void simpleInitApp() {
        bulletAppState = new BulletAppState();


        mat_terrain = new Material(assetManager, "Common/MatDefs/Terrain/Terrain.j3md");

        mat_terrain.setTexture("Alpha", assetManager.loadTexture(

        Texture grass = assetManager.loadTexture(
        mat_terrain.setTexture("Tex1", grass);
        mat_terrain.setFloat("Tex1Scale", 64f);

        Texture dirt = assetManager.loadTexture(
        mat_terrain.setTexture("Tex2", dirt);
        mat_terrain.setFloat("Tex2Scale", 32f);

        Texture rock = assetManager.loadTexture(
        mat_terrain.setTexture("Tex3", rock);
        mat_terrain.setFloat("Tex3Scale", 128f);

        AbstractHeightMap heightmap = null;
        Texture heightMapImage = assetManager.loadTexture(
        heightmap = new FlatHeightmap(128);

        terrain = new TerrainQuad("my terrain", 65, 513, heightmap.getHeightMap());
        terrain.setLocalTranslation(0, 0, 0);
        terrain.setLocalScale(2f, 0.5f, 2f);

        TerrainLodControl control = new TerrainLodControl(terrain, cam);

        terrain.addControl(new RigidBodyControl(0));

        //Add the ball
        Sphere sphere = new Sphere(20, 20, 2);
        ball = new Geometry("ball", sphere);
        Material material = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
        material.setColor("Color", ColorRGBA.White);
        ball.move(0, 20, 0);
        ballBody = new RigidBodyControl(CollisionShapeFactory.createDynamicMeshShape(ball), 1);
//        ballBody = new RigidBodyControl(new SphereCollisionShape(2), 1);

        cam.setLocation(new Vector3f(-50, 30, 50));
        cam.lookAt(new Vector3f(0, 10, 0), Vector3f.UNIT_Y);


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@ndebruyn: Please provide code for the FlatHeightmap class.

public class FlatHeightmap extends AbstractHeightMap {

    private int size;
    private float[] heightmapData;

    public FlatHeightmap(int size) {
        this.size = size;

    public boolean load() {
        heightmapData = new float[size * size];
        return true;

    public float[] getHeightMap() {
        return heightmapData;

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@ndebruyn: I’ve reproduced the issue you reported, and it’s a bug in Minie.

In the test app, disabling contact filtering as follows works around the bug:

        RigidBodyControl rbc = new RigidBodyControl(0);

So I’m convinced it’s related to contact filtering.

Contact filtering is a feature I added to Minie v4.5 in order to solve Minie issue #18. If you don’t plan to use BetterCharacterControl with terrain, then perhaps you don’t need contact filtering.

It’s curious that the bug manifests when the ball has a HullCollisionShape (generated by createDynamicMeshShape()) but not with a MultiSphere, nor with a SphereCollisionShape (which is what new RigidBodyControl(1) would generate). So far, I don’t have a good explanation for why the ball’s collision shape matters.

I’ll continue investigating.

EDIT: I’ve opened an issue at GitHub.