[Kalcor]

When you bake the lighting to vertex colors, it'll preserve any ray tracing.

The instant transitions are done with timed objects, not vertex colors.

The world objects in GTA3/Vice City only have a single set of vertex colors. When R* wanted change an object to night colors, there are 2 seperate models and they'd use timed objects.

In San Andreas, every object can have two seperate vertex color layers, and these are automatically blended as time passes in the game. There are still timed objects used to add lights to windows on big buildings etc.