Create a Voronoi diagram in the first octant. You specify a space and a grid width. The center of each cell will be distributed in each grid randomly.
size: 3 value array [x, y, z].
grid_w: The width of each grid.
seed: Seed value for random number generator for repeatable results.
spacing: Distance between cells. Default to 1.
use <voronoi/vrn3_space.scad>; vrn3_space( size = [20, 15, 10], grid_w = 5 );