Author Topic: True glide  (Read 3012 times)

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This game is beautiful and a blast to play, so this has no disrespect in its critique.

I tried searching and can't find any mention, but the glide does not feel like a true glide. During the training mission I tested the glide trying to orbit the Theseus and the viper kept pulling forward as i pointed the nose at the battlestar, getting closer and closer. A true glide would not do this. My comparison is Tachyon: The Fringe. That game had a true glide feature and i mastered pinpoint subsystem killing on caps with it. I will keep testing it, but at this point it feels like a partial glide, not executing as Aethers guide seems to describe it. Bear in mind i have love for the series and this game, and it might be a limitation of FS2, but if i'm off base, please let me know. The game is an amazing accomplishment aside from that.

 
Uh, if you were trying to set up an orbit the way I think you were then you have to have your throttle setting, velocity and radius from your target all at exactly the right amount, or you will end up drifting towards or away from it. Are you sure you didn't just miscalculate?
The good Christian should beware of mathematicians, and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell.

 

Offline Herra Tohtori

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This game is beautiful and a blast to play, so this has no disrespect in its critique.

I tried searching and can't find any mention, but the glide does not feel like a true glide. During the training mission I tested the glide trying to orbit the Theseus and the viper kept pulling forward as i pointed the nose at the battlestar, getting closer and closer. A true glide would not do this. My comparison is Tachyon: The Fringe. That game had a true glide feature and i mastered pinpoint subsystem killing on caps with it. I will keep testing it, but at this point it feels like a partial glide, not executing as Aethers guide seems to describe it. Bear in mind i have love for the series and this game, and it might be a limitation of FS2, but if i'm off base, please let me know. The game is an amazing accomplishment aside from that.


Try setting throttle to zero when in glide mode.


When you have throttle on, the spacecraft will eventually equalize your heading and vector.

The only realy limitation on the glide mode is top speed - you cannot accelerate indefinitely due to gameplay reasons (and engine restrictions, collision detection for example would be impossible at arbitrarily high speeds and you would pass through objects).

This is, incidentally, also why the heading and vector will equalize after some time. In reality, if your ship's nose is perpendicular to velocity vector and you apply thrust, your velocity in original direction will not change - instead, your total velocity will be the pythagoran sum of your velocities in three dimensions:

v2 = vx2 +  vy2 + vz2

In reality, you could increase your velocity to any direction by simply applying thrust in that direction.

However, since in this game the total velocity is limited, applying thrust on, say, vx direction will eventually reduce the vy and vz velocities, until you are traveling only in the direction of thrust - in this example, v = vx; and thus, it appears that the ship will eventually travel in the direction it is pointed at, if you also apply thrust in that direction.


However, as long as your total velocity is less than your total velocity limit, the glide feature should be exactly, or very close, to Newtonian glide.

Additionally, as long as your total thrust is exactly zero (acceleration = 0), the glide feature is exactly what you would expect from Newtonian mechanics.



The orbit trick is possible to do, but almost impossible to do so that you can have perfectly constant thrust (centripetal force) and perfectly circular orbit.

Perfectly circular orbit means you would have to turn your ship at exactly the same rate as your orbit around the centre point proceeds.

Your centripetal acceleration depends on your orbital velocity and radius of orbit, and both affect the rate of turn you have to keep going.

Then, your thrust level depends on following factors:

-how far from the center point you start your orbit at
-how fast you are moving when you start your orbit

When you are very close to the orbit target, you need high thrust because you need a lot of centripetal acceleration.

When you are further from the orbit target, and possibly moving slower on your trajectory around it, then you need less thrust.

Unless you can absolutely nail these parametres, it's more than likely that your distance from the target will change depending on your thrust level and rate of turn.

Thus, the trick is easiest to do when you constantly adjust your thrust and rate of turn to keep the target in view and the distance approximately the same.


This is a completely manual process, and you need to practice it a lot to become proficient in it.


Also: The closer your orbital velocity is to the total speed limit, the more the behaviour of your ship will deviate from the perfect Newtonian behaviour. At small speeds, the orbit trick works quite well.

Since the top velocity is limited to relatively small value (due to aforementioned gameplay reasons), it might be impossible to orbit a target as fast as you would wish to, which would perhaps limit its practical utility in this game.
« Last Edit: October 09, 2012, 11:05:37 am by Herra Tohtori »
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline jr2

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Wait.  I think he's saying that he was trying to glide and thrust was still being applied.  Perhaps throttle position was set after Glide was engaged?

EDIT: Ninja'd

 
Yeah, he seems to have been trying to circle the Theseus by applying a constant force towards it whilst moving tangentially. Based on what Herra said it sounds like the radial thrust is sapping tangential velocity, resulting in the fighter slowly spiralling inwards. I suspect fixing it would require a rework of the damping physics.
The good Christian should beware of mathematicians, and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell.

 

Offline Herra Tohtori

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Yeah, he seems to have been trying to circle the Theseus by applying a constant force towards it whilst moving tangentially. Based on what Herra said it sounds like the radial thrust is sapping tangential velocity, resulting in the fighter slowly spiralling inwards. I suspect fixing it would require a rework of the damping physics.

Yep, that's probably what happens. I haven't tried long orbits around a target myself, but for a section of the arc it did seem to work.

Fixing it would probably indeed require modification of damping physics, or increasing the maximum velocity, but considering the potential benefit from such a modification would be quite marginal compared to the work it would likely require, I wouldn't hold my breath waiting for it.
There are three things that last forever: Abort, Retry, Fail - and the greatest of these is Fail.

 

Offline Sushi

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Yeah, there's all sorts of silly weirdness going on with how damping (and velocity ramping) are applied when thrusting in glide mode. It's basically the best we could do while 1) not rewriting the entire physics system of FSO and 2) still making it feel like your ship follows more or less the same laws of physics in and out of glide mode.

 
In Tachyon, you could move parallel to an object, hit glide and point at it,  then toggle spurts of glide while pointing at the object. Done right, you orbit, but speed decays each time you go from glide on to glide off. But the whole orbit thing isnt my beef.

While in glide sliding sideways and looking at the Theseus, i found there was still nose forward thrust being applied. It was my understanding that all forward thrust is cut when glide is on and you could point anywhere but still travel along the vector the viper was going when glide was applied. I will work around it regardless. I was just seeing if anybody encountered this or if I'm just special. And no i dont like being special.


Btw, the best you could do? You did better than any damn corporation could and you did it without pay. My hat off to you. I figured it was a limitation of the fs2 engine, not a codewrite failure. Really its only noticed against a static object. And the maneuvering thrusters could help too.
« Last Edit: October 10, 2012, 08:44:34 am by Slicerjen »

 

Offline Dragon

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Just cut the engines when you start gliding. Diaspora features a realistic glide mode, which is really just "assistance off" mode. Your ship behaves in accordance to a fairly good approximation of the Newtonian flight model.

 

Offline Sushi

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Yeah, the key thing to remember is that engines still work in glide (they get cut by default when you hit the key, but if you wiggle the throttle at all that will be undone). That's a feature, not a bug. :)

As Dragon pointed out, we intended for Glide to behave more like "vector assistance off" than "engines off." You're still subject to the same (scientifically silly, but important to the game) speed limits, but unless you apply throttle or thrust in some direction you WILL just keep flying along the same vector.

 
What is the current vMax?  A Viper VII has an Overclock of 110 and that is also its max forward speed.  I presume these numbers are meters per second also?  Just curious.

 

Offline MatthTheGeek

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