GridInit
geometry/grid.types.ts:13Factory invoked once per cell when a Grid is constructed, used to
seed each cell's Cell.data payload. Return null to leave a cell
empty.
(x: number, y: number) => TData | null 
Factory invoked once per cell when a Grid is constructed, used to
seed each cell's Cell.data payload. Return null to leave a cell
empty.
(x: number, y: number) => TData | null