Flattens a 3D cluster cell coordinate into a linear index (X-major, then Y, then Z).
Cell coordinate along the X axis.
Cell coordinate along the Y axis.
Cell coordinate along the Z axis (depth slice).
Grid dimensions from computeClusterCounts().
computeClusterCounts()
Flattens a 3D cluster cell coordinate into a linear index (X-major, then Y, then Z).