In the HDK, I would like to store a vector value on each of the cell faces of each voxel in a SIM_VectorField. It looks like a field can distinguish between the different parts of a voxel, for example, the SIM_FieldSample enum has a separate value for each face: SIM_SAMPLE_FACEX, SIM_SAMPLE_FACEY, and SIM_SAMPLE_FACEZ. Does this mean I can store a value for each of the three cell faces (along with the cell center, if desired) for every voxel in a single SIM_VectorField? If so, how can I do that? Or do I need to set up a separate SIM_VectorField to store values for each axis' face?