[SOLVED]How to move wheels connection point in vehicleControl

Troubleshooting physics
1

I’ve trying to make helicopter, based on fancyCar eample.

I’m creating CompoundCollisionShape with only body of vehicle, and move it down. (if a adding whole model it starts to roll, for my purpose shape of CompoundCollisionShape is not really important)

     Spatial mi17Node = assetManager.loadModel(MI17_SCENE_LOCATION);
   Geometry body = findGeom(mi17Node, "body");
   
    CollisionShape carHull = CollisionShapeFactory.createDynamicMeshShape(body);
    CompoundCollisionShape compoundCollisionShape=new CompoundCollisionShape();
    carHull.setScale(new Vector3f(0.5f,0.5f,0.5f));
    compoundCollisionShape.addChildShape(carHull, new Vector3f(0,-1,0));
    
    vehicleControl = new VehicleControl(carHull, 400);

But when i adding whhels they connected to "strange "point. My hypothesis - this point is center of whole objects from .scene file
When i move compoundShape this “point” stays at same place

code for adding wheels:

private void addOneWheel(Spatial node, String nameOfPart, Vector3f addToCenter, Boolean isFrontWheel){
Geometry wheel = findGeom(node, nameOfPart);
wheel.setLocalRotation(new Quaternion().fromAngleAxis((float)Math.toRadians(180), new Vector3f(0, 1, 0)));
wheel.center();
BoundingBox box = (BoundingBox) wheel.getModelBound();
radius = box.getYExtent();
vehicleControl.addWheel(wheel.getParent(),box.getCenter().add(addToCenter), wheelDirection, wheelAxle, 0.2f, radius, isFrontWheel);
}

example.jpg1313×833 151 KB

my question is: how can i move this point? maybe i misunderstood something in process of vehicle creation?
thank you

2

Don’t move the collision shape down, move it up. The center of mass is always at the center of the collision shape.

3

thank you for reply,

when i move collision shape up it still fall

example.jpg947×647 93.6 KB

i’ve tried to move my Spatial mi17Node but it nothing happens (i think this point is center of coordinates).

what i need to move besides collision shape to make the model does not fall?

4

Again, the center of mass is at the center of the collision shape. The collision shape is generated from the node or geometry you pass (if you use the CollisionShapeFactory). So the center of the geometry or node defines the center of mass in that case. So to move it down attach the geometry to a node (the node center is later the center of mass, remember), then attach the geometry to that node and move it up in the node, then use the CollisionShapeFactory on the node.

5

Thank you, i’ve moved geometry up and everything works fine