//Start a new part because of the different material
            partBuilder = builder.part("shadow_plane",
                    GL20.GL_TRIANGLES,
                    Usage.Position | Usage.Normal | Usage.ColorUnpacked,
                    new Material(ColorAttribute.createDiffuse(Color.WHITE)));

            //create on X/Y plane (consider Z extrude direction)
            float margin = box.getHeight();


            //extend base of the Bbox
            //Get top corners (x1x), extend them of the height (to avoid extending box under the bottom)
            // then get bottom corners (x0x) to have the plane size
            Vector3 innerCorner000 = box.getCorner000(new Vector3());
            Vector3 innerCorner001 = box.getCorner001(new Vector3());
            Vector3 innerCorner100 = box.getCorner100(new Vector3());
            Vector3 innerCorner101 = box.getCorner101(new Vector3());
            box.ext(box.getCorner010(new Vector3()), margin);
            box.ext(box.getCorner011(new Vector3()), margin);
            box.ext(box.getCorner110(new Vector3()), margin);
            box.ext(box.getCorner111(new Vector3()), margin);

            //then get the new values
            Vector3 outerCorner000 = box.getCorner000(new Vector3());
            Vector3 outerCorner001 = box.getCorner001(new Vector3());
            Vector3 outerCorner100 = box.getCorner100(new Vector3());
            Vector3 outerCorner101 = box.getCorner101(new Vector3());


            VertexInfo v1 = new VertexInfo();
            v1.hasPosition = v1.hasNormal = v1.hasColor = true;
            v1.color.set(Color.RED);
            v1.position.set(outerCorner000);
            v1.normal.set(Vector3.Y);

            VertexInfo v2 = new VertexInfo();
            v2.hasPosition = v2.hasNormal = v2.hasColor = true;
            v2.color.set(Color.WHITE);
            v2.position.set(outerCorner001);
            v2.normal.set(Vector3.Y);

            VertexInfo v3 = new VertexInfo();
            v3.hasPosition = v3.hasNormal = v3.hasColor = true;
            v3.color.set(Color.BLACK);
            v3.position.set(innerCorner001);
            v3.normal.set(Vector3.Y);

            VertexInfo v4 = new VertexInfo();
            v4.hasPosition = v4.hasNormal = v4.hasColor = true;
            v4.color.set(Color.BLUE);
            v4.position.set(innerCorner000);
            v4.normal.set(Vector3.Y);

            partBuilder.rect(v1, v2, v3, v4);