This is all irrelevant, portals can't be placed on moving objects.
The earth is a moving object, so all portals are moving through 3d space at all times.
It's probably dependent on the reference frame of the first portal, or the portal gun.
It can't be the portal gun since you can shoot it while flying through the air.
that is a game engine limitation, not an in-universe physics limitation.
Games and real life are the same! Now if you'll excuse me I'm going to jump off a bridge then use an energy drink to heal my broken bones.
In Portal 2 you place portals on moving surfaces to cut the neurotoxin pipes.
This is all irrelevant, portals can't be placed on moving objects.
The earth is a moving object, so all portals are moving through 3d space at all times.
It's probably dependent on the reference frame of the first portal, or the portal gun.
It can't be the portal gun since you can shoot it while flying through the air.
that is a game engine limitation, not an in-universe physics limitation.
Games and real life are the same! Now if you'll excuse me I'm going to jump off a bridge then use an energy drink to heal my broken bones.
In Portal 2 you place portals on moving surfaces to cut the neurotoxin pipes.