OpenGL has a concept of start time and end time (or head time) specifying range of displayed objects.
(All these attributes could be generalised to all types of viewers.)
“fade” diminishes the brightness of earlier times.  Lines have a vapour-trail effect.
It can display the head time as text.
It can display the “light front”, I.e., the wavefront of light starting at time zero at position given.
Pans at speed of light since v = dx/dt = 0.3 mm / 0.001 ns