It is obvious from the Mainhall....
Ugh. Do you see gravity there?
All I see is that everyone remains sticking to the floor or a lift, but this doesn't mean they do have artificial gravity.
Look at it carefully. There are several things that show that either gravity is present or that Volition was too lazy to bother with showing the effects without it.
#1
Watch the guy going down the lift. After that he _walks_ down stairs. The acting of walking down stair requires gravity. It is possible without gravity, but you would have to pull yourself down using either you legs or arms resulting in a quite unnatural looking posture. The man walk down as if there wasn't any sort of difference.
#2
The guy in the chair. He is _leaning_ on his elbow. I can't see how this would be comfortable in zero-g. Also, when you hover the mouse over him, he turns towards you. Unless his entire rear end and back is also magnetically stick to his chair, the top of his body would noticeably turn past you a bit when he's trying to face you (since only his shoes are attached). In addition, he will also semi-standing up having nothing to keep his rear on the chair while his legs turn him.
In any case, wlkng with magnetic boots in zero-g looks quite different from normal walking (since it's not really walking strictly by definition, that is, falling and catching yourself using the other foot).
[edit] Also, the shape of Terran capital ships make it quite impossible to have rotational acceleration as a source of pseudo-gravity. They could only possible rotate along the length of the ship (due to it's shape), but since the distances involved are so small (yes it's actually small for this application), the "gravity" generated would be accompanied by a noticable sideways pull. Not to mention the motion sickness.
Shivan ships seem to have no gravity. In fact, the scientists expressed a degree of surprise at that and comments that perhaps Shivans evolved in zero-G.
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