In this example I show the Bars3D plot with 0.2 unit gap between bars.
Image obtained in MuPAD.
Note: MuPAD by default does not create coordinate system axes for Bars3D. I added them using in the last plot statement Axes=Boxed. The gap between bars was created using XGap=0.2, and YGap=0.2 parameters in Bars3D declaration.
The same model in JavaView. Both images look identical.
In JavaView, in Display panel I added Antialias and Z-buffer turned ON. This makes perfect match between both images.