public void updateGeometry() {
        VertexBuffer vb = this.getBuffer(Type.Position);
        FloatBuffer posBuf = this.getFloatBuffer(Type.Position);
        posBuf.clear();
        for (int i = 0; i < skeleton.getBoneCount(); ++i) {
            Bone bone = skeleton.getBone(i);
            Vector3f head = bone.getModelSpacePosition();

            posBuf.put(head.getX()).put(head.getY()).put(head.getZ());
            if (boneLengths != null) {
                Vector3f tail = head.add(bone.getModelSpaceRotation().mult(Vector3f.UNIT_Y.mult(boneLengths.get(i))));
                posBuf.put(tail.getX()).put(tail.getY()).put(tail.getZ());
            }
        }
        posBuf.flip();
        vb.updateData(posBuf);

        this.updateBound();
    }
The method updates the geometry according to the positions of the bones.
jme3-core/src/main/java/com/jme3/scene/debug/SkeletonPoints.java