The behavior of the centerline, 2D and 3D simulations is controlled by the settings in the Simulation Options dialog box, available in the Options menu. You can open this dialog box while a simulation is running and refine or coarsen the simulation on the fly. If you do open Simulation Options during a simulation, the simulation pauses until you close the dialog box. You’ll get an error message if you run the 3D simulation in a display showing fewer than 256 colors. The simulation will still run, but won’t look as good.
2D/3D shaded simulation options