So, this does seem to take the angle I'm flying at into account. If I'm accelerating to 99.9% the speed of light, and I yaw 180deg the view, I start "decelerating".
What happens if I keep maximum acceleration and pitch up 90deg? The software seems to keep flying on the original vector. Is this a bug or is it intended to be a simulation of how light would behave under those circumstances?
Not the way I see it. If I accelerate modestly (0.2m/s2) to just above 30% of c where the movement is noticable enough and then put the direction of travel just beyond one of the corners (e.g. just beyond the top right) by turning the view then the direction of travel will move slowly towards the center of the screen on its own - giving a slight sense of turning in the beginning - as one would expect of current velocity vector and the velocity accummulated from acceleration vector (always towards the center) add up. At velocities close to c the already huge velocity vector dominates and no chance of perpendicular (or any angled) acceleration make any effect on the velocity vector direction: the diagonal of the two can never go beyond c. The velocity vector locks in. (probably why those traveling near the speed of light don't age much, their particles cannot interact that freely with each other when their movement is locked in to a common travel vector?).
And here I'd observe that the acceleration value is measured in the local system where time slows down relative to the observer's system, while the speed is measured in the observer's system (naturaly, my speed relative to me is always zero).
Sure, from the observer's system (home planet "stationary" the speed is measured from) it can't go faster than c... but that's where I don't think it's accurate. From the flyer's perspective, if you're close to c (as viewed from home) and suddenly accelerate at a 90deg angle, that shouldn't bleed off your speed forward, or be limited by your speed forward. Only from the distant viewer's perspective would those two velocities combined max out at c. From your perspective they wouldn't.
The near c component of the velocity remains near c with applying 90 deg acceleration, hence that the velocity vector will remain towards this near c regardless of 90 deg acceleration characteristics. For a significant change one need to apply acceleration that has very significant deceleration component to this near c velocity vector (significant amount of >90deg acceleration applied, best to be close to 180deg).
yeah, and that's the way it would appear to a motionless observer. Buy not how it would appear to you. Remember, once you have achieved .99c velocity, no longer accelerating, you are standing still. From your perspective, any new acceleration at a 90deg angle should begin accumulating light from that direction.
What happens if I keep maximum acceleration and pitch up 90deg? The software seems to keep flying on the original vector. Is this a bug or is it intended to be a simulation of how light would behave under those circumstances?