3D visualization of electric field: point charges, lines of force, equipotential surface.
e - Switch equipotential surface on/off
f - Switch lines of force on/off
p - Add positive charge at cursor position or increase existing charge value by one unit
n - Add negative charge at cursor position or decrease existing charge value by one unit
r - Reset state to starter
Del - Delete all charges
Left click + mouse move on charge - Drag the charge
Left click + mouse move on scene - Drag the scene
Right click + mouse move on scene - Rotate the scene