Create a 3D bar graph in the viewport, representing the density of points underneath each bar.

Input parameters:

1. Pt → Points to sample.
2. Bn → Outer boundary of the entire bar graph.
3. Nx → Number of bars along the graph x-axis, or the approximate total number of bars if Ny is not set.
4. Ny → Optional number of bars along the graph y-axis. If omitted, the Nx value controls the total number of bars.
5. Gr → Optional gradient which maps bar valence to bar colour.
6. Fh → Optional function which bar valence to bar height.

Output parameters:

1. Ms → Mesh representing the 3D bar graph.