The following section contains information from a previous version of StarCraft II which is no longer valid.
Bunkers were initially StarCraft bunkers dropped into the 3D engine of StarCraft II. When Blizzard began redesigning the buildings, the main elements of the bunker were simplified and key shapes made stronger. The primary intention for this building was to make the visual indication of terran occupants more obvious, so the shape changes when terrans load inside and the interior lights are more visible.
A bunker could be salvaged while units are still in it; during this period, the units within can no longer use their abilities.
Infantry units could use abilities from inside a bunker except the SCV's repair ability. When a unit entered the bunker its special abilities became available within the bunker commands (load, unload, etc.). In June 2008, units within a bunker could use stimpack, EMP, nuke and Snipe. When medics were in the game, a medic inside a bunker could heal units both within and outside Bunkers, but a medic outside of a bunker could not heal units inside of a bunker.
↑Yes, I can confirm that some units get visual upgrades when you boost them through research.
Zerglings, Marines and Banelings are just some examples though, as there are other units that are getting a visual upgrade.
For example, Battlecruisers have the ability to choose between three specializations:
- Defensive Matrix (a shield that absorbs damage)
- Missile Pods (Air to Air AoE damage)
- Yamato Cannon (honestly, do I need to introduce this one? :) )
Each one of these specializations changes the graphic of the battlecruisers, thus making it easily recognizable.
Just to clarify things up: you can only have one specialization per Battlecruiser, and once you choose you cannot switch to another one.
But not only units are affected by this visual upgrades, even buildings are being visually upgraded.
Let's talk about Bunkers: when the NeoSteel Frame upgrade is completed (+2 cargo space) the bunker actually gets bigger and taller. Zhydaris. 2009-12-01. Visual Upgrades?Battle.net StarCraft II General Discussion Forum. Accessed 2009-12-01.