[SOLVED] How to get intersection areas?

Troubleshooting graphics
1

Hello, I’m created 2 Geometries, And i want to take intersection area of this two geometries. Something like this: (Yes, i’m a master of Paint)

Screenshot_from_2015-11-04_14_31_32.png1366×768 28.7 KB

How i can take intersection areas?
At least the coordinates of the corners will be good too. This is my code:

@Override
public void simpleInitApp() {
    Geometry obj1 = attachShape(new Box(1, 1, 1), new Vector3f(0, 0, 0), ColorRGBA.Blue, "Box1");
    Geometry obj2 = attachShape(new Box(.5f, 1, .5f), new Vector3f(0, 1, 0), ColorRGBA.Green, "Box2");

    CollisionResults results = new CollisionResults();
    rootNode.getChild(0).collideWith(rootNode.getChild(1).getWorldBound(), results);
}

private Geometry attachShape(Mesh shape, Vector3f pos, ColorRGBA color, String name) {
    Geometry g = new Geometry(name, shape);
    g.setLocalTranslation(pos);
    Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
    mat.getAdditionalRenderState().setWireframe(true);
    mat.setColor("Color", color);
    g.setMaterial(mat);
    rootNode.attachChild(g);
    return g;
}

And sorry for my English.

2

CSG

For example this Another CSG solution
Or this Solid geometry (not hollow) - #6 by justry

You could also write special purpose code for cubes, but CSG is for any geometry type.

3

Thank you.

4

You’re welcome. :chimpanzee_smile:

5

Now i have some problems with update. After rotate my shapes and regenerate my GSM object, it dont take changes of second shape.

Screenshot from 2015-11-07 20:17:54.png1366×768 62.8 KB

public void simpleInitApp() {
    CSG_obj1 = attachShape(new Box(1, 1, 1), new Vector3f(0, 0, 0), ColorRGBA.Blue, "Box1");
    CSG_obj2 = attachShape(new Box(.5f, 2, .5f), new Vector3f(0, 0, 0), ColorRGBA.Yellow, "Box2");
    CSG_obj = new CSGGeometry("Geom");
    CSG_obj.setMaterial(new Material(assetManager, "Common/MatDefs/Misc/ShowNormals.j3md"));
    rootNode.attachChild(CSG_obj);
    CSG_obj.addShape(CSG_obj1);
    CSG_obj.addShape(CSG_obj2, CSGGeometry.CSGOperator.INTERSECTION);
    CSG_obj.regenerate();
}

private CSGShape attachShape(Mesh shape, Vector3f pos, ColorRGBA color, String name) {
    CSGShape g = new CSGShape(name, shape);
    g.setLocalTranslation(pos);
    Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
    mat.getAdditionalRenderState().setWireframe(true);
    mat.setColor("Color", color);
    g.setMaterial(mat);
    rootNode.attachChild(g);
    return g;
}

public void simpleUpdate(float tpf) {
    i++;
    if (i == 10) {
        CSG_obj1.rotate(tpf, tpf, tpf);
        CSG_obj2.rotate(-tpf, -tpf,  -tpf);

        CSG_obj.regenerate();
        i = 0;
    }
}
6

I did not try that CSG library yet - maybe @wcomohundro can answer your question?

I guess it’s something simple like you not calling updateGeometricState or updateBounds or something like that…

7

There was a bug in the CSG code where the updated Meshes were not being refreshed on a secondary call to .regenerate( ). This has been fixed in b07112015, available on SourceForge.

Dima - your code is just fine and should now work. It was strictly a problem inside CSG. Your sample makes a nice demo of how CSG is supposed to work. Please contact me if you need anything else. I will also be monitoring this thread from now on.

Ogli - thanks for pointing Dima to my code and for referencing me so that I saw the problem. I would love to have more people exercising the code and reporting problems back to me. The SourceForge ticket system is the best way to get my attention.

8

CSG work on Android?

9

I have no Android test environment so I have never tried it.

It is all just Java, but I do not know what kind of constraints Android imposes.
CSG is about the Mesh construction with nothing special about Rendering. So
long as Android can deal with standard Meshes, I would hope it would all work.

Let me know about any results you get with Android, good or bad, and I will
include it in my documentation.

10

I’m had NoClassDefFoundError when i create CSGGeometry and CSGShape objects. I think problem is in gradle generated JME3 Libs. Your libs i connect native.