public Vector3f getCamCell(Vector3f location) {
        Vector3f tile = getTileCell(location);
        Vector3f offsetHalf = new Vector3f(-0.5f, 0, -0.5f);
        Vector3f shifted = tile.subtract(offsetHalf);
        return new Vector3f(FastMath.floor(shifted.x), 0, FastMath.floor(shifted.z));
    }
Get the location in cell-coordinates of the specified location.
Cell coordinates are integer coordinates, usually with y=0, each
representing a cell in the world.
For example, moving right in the +X direction:
(0,0,0) (1,0,0) (2,0,0), (3,0,0)
and then down the -Z direction:
(3,0,-1) (3,0,-2) (3,0,-3)
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainGrid.java