Jumpgate Evolution - Dev Journal: Flight Dynamics

[Mrbloodworth]

Mods: If you this this would be better to be merged with the existing JG:E thread, please do, but i felt this warranted a new thread, as its a largely discussed topic and is really the first concrete info about the game.


Jumpgate Evolution - Dev Journal: Flight Dynamics

Jumpgate Evolution owes the basis of its flight engine to NetDevil's first product, Jumpgate. Arguably a unique feature, the Jumpgate flight engine allowed the game to be distinguished as an online spaceflight simulator, rather than a run-of-the-mill MMORPG, which were only then (in 2001) beginning to be churned out by a nascent industry. Jumpgate's distinguishing element was that, as in prior spaceflight and combat games such as Elite, the Wing Commander series, the X-Wing series, Freespace, and Alliegiance, the player directly pilots their ship, often with a joystick instead of a mouse.


Though often described as realistic when compared with other games' flight models, the Jumpgate flight engine is neither strictly realistic, nor is it by any means arcade-style. Perhaps the simplest description is "playably realistic". Underlying the flight model is basic Newtonian physics: engines apply a force to the ship's mass, which accelerates in response. During experimentation with early builds, the original Jumpgate developers quickly recognized that a wholly realistic flight engine would be incompatible with their vision of hands-on flight. Strictly realistic spaceflight creates a demoralizing list of playability issues: unreasonably large potential speeds, impossible reaction times required of players, inability of ships moving at greatly different speeds to fight or even interact effectively, as well as complications to travel because of the need to slow down again to rendezvous with a destination, just to name a few of the problems. The ultimate goal of Jumpgate was to re-create white-knuckle fighter combat as seen in movies and TV such as Star Wars, Battlestar Galactica, or Babylon 5, so solving the gameplay problems by departing from the hands-on control paradigm just wasn't an option.

The original flight engine was made playable by adding an omnidirectional drag term in the equation of motion. Though unrealistic, the drag component offered huge playability gains, and became the necessary savior of the otherwise problematic Newtonian foundation. Ships suffered an upper speed cap due to drag, which in turn brought the reaction times needed for control well into the natural range of a human pilot, and simultaneously kept all ships able to easily interact. Jumpgate's "D.A.N.C.E.R." engine was thus born. The engine provided playable "spaceflight", while retaining the challenges and advantages the development team wanted to keep.

So much for our journey down Memory Lane. While the Jumpgate Classic flight engine succeeded in being playable, it failed to be accessible. It can be argued that this was not so much a drawback of the engine itself, but rather of the control scheme. Jumpgate Evolution continues to support joysticks (and by extension, gamepads), but first and foremost among our adaptations, the mouse and keyboard interface has been made much more straightforward for the player to use. The familiar WASD setup has become the default control core, with other keys chosen in a sensible and ergonomic pattern. Along with control adjustments, flight response has also been enhanced by tweaks to the default flight model. Drag has been slightly increased, and braking thrusters are more powerful, combining to offer the player greater control of their ship. Vertical and lateral thrusters have also been added, analogous to familiar FPS "strafing" controls, which offer the player new options for modifying their ship's trajectory. All these changes were implemented as part of a directive to make flight easier to understand, and the ship controls easier to use. However, it was quickly obvious that the drag changes in particular altered some aspects of flight so familiar to players of Jumpgate Classic - and that those aspects would be very desirable to retain.

The dilemma was only momentary, and its solution was simple. The original flight model, in which drag is weaker and momentum more significant, has been retained (including the new controls and directional thrusters). A toggle has been set up allowing the player to switch between the new default flight model and the original one. Fictionally, players are toggling the ship's "inertial dampers" - an idea with venerable science fiction roots. Offering this choice permits Jumpgate Evolution to keep the best of both worlds. Players begin the game set to use the new flight model, which is easier to understand and fly with, but can choose to turn it off to gain the performance of the original model. The pilot can switch on the fly, depending on what kind of flight profile is desired, even in the heat of battle.

We've discovered that being able to switch flight models in real time adds a fun and slightly unexpected tactical dimension, in addition to the convenience that was fully intended. During routine testing, some of us on the team now find ourselves using the toggle frequently. For example, when creeping through a clump of asteroids, I'll leave the dampers on so I have tighter control over my speed and direction. If I attack some pirates I find among the rocks, I might cut the dampers out in the firefight, so I can pivot and fire at a pirate on my six while still pursuing his buddy. The encounter could doubtless be handled successfully by using either flight mode throughout, but by yielding the option to the player, we hope that the additional element of personal choice is received as an enhancement to the fun piloting experience we're trying to build into Jumpgate Evolution.

Article By: Steve "Istvan" Hartmeyer, Programmer

[SnakeCharmer]

The screenies look good.  Action packed.  But then again, so does EvE, which turns into an excel snooze.

Is JG:E lots of pew pew pew zoom!!! or is it EvE?  Diku ships instead of diku cars (Auto Assault)?

What's the skinny?

[tazelbain]

It would seem to me that newtonian physics would be better suited for EvE were you aren't relying on human reflexs for navigation.

[Baldrake]

You know, cars are also subject to Newtonian physics. Yet real cars are effectively controlled with what amounts to WASD (accelerate, slow down, turn left, turn right.) I've never understood the motivation for the original Jumpgate-style controls. So your civilization is advanced enough to achieve advanced space flight, but too stunted to insert a computer between the controls and the thrusters so as to make them easy to use?

[Draegan]

There isn't wind resistance in space!

I want this game.

[Mrbloodworth]

The screenies look good.  Action packed.  But then again, so does EvE, which turns into an excel snooze.

Is JG:E lots of pew pew pew zoom!!! or is it EvE?  Diku ships instead of diku cars (Auto Assault)?

What's the skinny?

IT's twitch, as in Wing commander/X-wing VS. Tie

Aim and piloting required to hit things. Point at and fire. IE: lots of pew pew pew zoom!!!

[Ratman_tf]

There isn't wind resistance in space!

Wouldn't realistic space combat be more like pushing a button on a computer and having the system do a metric fuckton of calculations, fire some smart missle, and then watch a blip disappear on a screen?

[/pedant] I know, there's always a trade off between realism and fun. 

[Draegan]

There isn't wind resistance in space!

Wouldn't realistic space combat be more like pushing a button on a computer and having the system do a metric fuckton of calculations, fire some smart missle, and then watch a blip disappear on a screen?

[/pedant] I know, there's always a trade off between realism and fun. 

 

[Baldrake]

There isn't wind resistance in space!

Yes, but cars don't rely solely on wind resistance to provide a braking function, now do they? The problem with classical Jumpgate was that (despite the "drag" they added) there's no reasonable way of slowing down, short of turning around and going the other way.

[Draegan]

My response was tongue and cheek.

However in space, once you go in one direction you won't stop unless some other force acts against you.  If you accelerate on a flat surface in a car, you will slow down due to friction of your tires and the air.

[Venkman]

You're forgetting solar wind. Ya know, for this big umbrella ships they have in Jumpgate

[Baldrake]

However in space, once you go in one direction you won't stop unless some other force acts against you.  If you accelerate on a flat surface in a car, you will slow down due to friction of your tires and the air.

Ok, I guess I was guilty of writing a short response when clearly a longer one was necessary.

Indeed a car will slow down due to wind resistance and friction. But if you're trying to maneuver in a parking lot, what you're actually using is your brakes. In a car, you have a simple user interface where you have one pedal to speed up, and another which slows you down. This user interface works nicely because you don't need to have any knowledge of how acceleration and braking are "implemented" - you simply need to step on the pedals.

In a Jumpgate ship, you have a "forward" control which engages some fictional propulsion mechanism. My complaint is, in any reasonably designed ship there would also be a "brake" mechanism which engaged said fictional propulsion mechanism in the other direction, but set up as a simple "slow the ship down" control.

Just because a ship obeys Newtonian physics doesn't mean that the ship's controls have to be low-level and hard to use. That's all I meant.

[Venkman]

Modern Battlestar Galactica Vipers plz. I mean come on. The only people who stick UI, gravity and friction limitations on space battles are scriptwriters.

[Sky]

In a Jumpgate ship, you have a "forward" control which engages some fictional propulsion mechanism. My complaint is, in any reasonably designed ship there would also be a "brake" mechanism which engaged said fictional propulsion mechanism in the other direction, but set up as a simple "slow the ship down" control.

Just because a ship obeys Newtonian physics doesn't mean that the ship's controls have to be low-level and hard to use. That's all I meant.

I'm with you. That kind of physics is wicked fun for pew pew, get up to speed, spin around 90 degrees and strafe someone without losing any momentum, or spin around 180 and fire at pursuers. It's the kind of stuff that makes it better than normal flight sims and one reason Wing Commander pwned.

But retro-rockets or whatever would be necessary and logical. I mean, you can turn and pitch already, you would logically have directional nozzles on all sides of the ship.

[Draegan]

However in space, once you go in one direction you won't stop unless some other force acts against you.  If you accelerate on a flat surface in a car, you will slow down due to friction of your tires and the air.

Ok, I guess I was guilty of writing a short response when clearly a longer one was necessary.

Indeed a car will slow down due to wind resistance and friction. But if you're trying to maneuver in a parking lot, what you're actually using is your brakes. In a car, you have a simple user interface where you have one pedal to speed up, and another which slows you down. This user interface works nicely because you don't need to have any knowledge of how acceleration and braking are "implemented" - you simply need to step on the pedals.

In a Jumpgate ship, you have a "forward" control which engages some fictional propulsion mechanism. My complaint is, in any reasonably designed ship there would also be a "brake" mechanism which engaged said fictional propulsion mechanism in the other direction, but set up as a simple "slow the ship down" control.

Just because a ship obeys Newtonian physics doesn't mean that the ship's controls have to be low-level and hard to use. That's all I meant.

Sure.  Different control schemed for different types of ships.

[DraconianOne]

They implemented Newtonian-ish physics in Elite 2: Frontier and to a certain extent in I-War (very much cut your thrust, spin your ship and shoot at what ever you had just passed while ostensibly flying backwards) - all very reminiscent of ship flight in both Bablyon 5 and new BSG. 

Personally, I hate it: give me Freespace or X-Wing type controls anyday.  It's all about the fun baby!

[Mrbloodworth]

Personally, I hate it: give me Freespace or X-Wing type controls anyday.  It's all about the fun baby!

They did.

[bhodi]

I remember trying to close with a target and being forced to do nothing but look at empty space while watching the distances meter (because of trajectory and my thrust being in one direction). That was a ton of fun let me tell you.

[ajax34i]

I-War 2 had Freespace-type controls, optional, or unassisted Newtonian, also optional, toggle between them by hitting N.  That simple.

For me, unassisted Newtonian is fun in combat, cause indeed flipping 180 and shooting your 'pursuer' is awesome.  However, it's a friggin pain to dock your ship, or try to get stationary relative to another ship (fly in formation, anyone?  lol try that with unassisted Newtonian).

So yes plz, put reverse thrusters in, and an optional computer to slow me down in space as if there was friction, because sometimes I might need to stop the ship while continuing to look forward at whatever I'm about to smash into, and having to flip my main thrusters around to do that sucks.

[DraconianOne]

I-War 2 had Freespace-type controls, optional, or unassisted Newtonian, also optional, toggle between them by hitting N.  That simple.

Now you come to mention it, they did in I-War too.  I just never got into it as a game so much.

[Lanei]

There isn't wind resistance in space!

Yes, but cars don't rely solely on wind resistance to provide a braking function, now do they? The problem with classical Jumpgate was that (despite the "drag" they added) there's no reasonable way of slowing down, short of turning around and going the other way.

I suppose the key word there is reasonable.  There was a 'brake' control in Jumpgate, its just that your braking thrusters were nowhere near as powerful as your engines.  It makes a sort-of sense, too, since the engines were the big tube-like ion-spitting things the ships were basically designed around, and the braking thrusters were a small cloud of vapor in the direction of travel.  If I'm not confusing it with another game, there was also a 'reverse course' button that would align your ship perfectly to put your engines onto your current vector (though I personally never had trouble using the vector indicator on the HUD for this), so you could do most of your slowing down with your engines, and the last bit of stopping with your thrusters.

My own preference is for flight models like Jumpgate and Allegiance rather than like Wing Commander.  Wing Commander is an undeniably great series of games, but you are essentially flying a plane in space, not a space-fighter.  In space, hauling back on the stick should whip your nose around a LOT faster than your vector is changing, without it being a special feature only on the last fighter class you upgrade to.  (I'm looking at you, Wing Commander 3)

I am happy to hear that the newer JG flight models will include better and more varied directional thrusters, I think it probably will help controllability of the ships a lot, especially the really large ones.   If you though a fighter in JG had a hard time stopping in a docking ring, try a cargo tow with a couple hundred tons of cargo aboard.  The brakes, they do nothing!!

[SnakeCharmer]

In space, hauling back on the stick should whip your nose around a LOT faster than your vector is changing, without it being a special

So, you basically want to remove G forces from a space fighter.  Makes sense. 

If you though a fighter in JG had a hard time stopping in a docking ring, try a cargo tow with a couple hundred tons of cargo aboard.  The brakes, they do nothing!!

But then, you have weight meaning something with a couple hundred tons of cargo.

Isn't weight kinda meaningless in space?

I'm a little rusty on my elementary school science, but that kinda doesn't make a whole of sense to me.

[justdave]

Isn't weight kinda meaningless in space?

I'm a little rusty on my elementary school science, but that kinda doesn't make a whole of sense to me.

You're confusing weight and mass. Just because something doesn't have a lot of weight (accelleration due to gravity, most especially of a planetary body) doesn't mean it doesn't have an assload of mass (momentum, etc.). 

So, you basically want to remove G forces from a space fighter.  Makes sense. 

Actually, now that I re-read this, that really misses the point. His point seems to be Falcon 4.0 + shoved into 'space' = bad. Perfectly understandable, even if it's geek city that'll never get made because it's not profitable.

[SnakeCharmer]

OK.  I got it now, after googling mass vs weight.  I think. 

Physics never was a strong point.

[bhodi]

There is already a Falcon 4.0 shoved into space. Well, OK, more like microsoft flight simulator. Anyway, it's got crazy, crazy depth.

The point I'm trying to make is that newtonian physics in space suck if you're playing from a first person view like wing commander... because when you are in a intercept path, you are almost never going to be looking at your target. The only "fun" way to play a game with newtonian physics is how we do it in the real world -- tell a computer where you want to go, and have *it* do the piloting.

It's fun from an overhead view, though -- look at subspace/continuum.

[justdave]

Okay, Falcon 4.0 was a bad example. I was more arguing the point that pulling back on the stick wouldn't necessarily mean you take any g's, and was groping for an example of something with an atmospheric model.

I think the best compromise I've seen so far is the I-War/I-War 2 scheme, where you have the computer trying to emulate an atmospheric model, by default, but you can turn it off if you want. Personally, I'm exactly the opposite and found it more fun with it off most of the time, but I also realize that I'm a mu-tant.
And yes, Orbiter is teh awesome (you have to love a game with an MFD specifically for Hohmann transfer orbits), but that having been said, it has too much detail even for me for your average evening of blowing the shit out of people. 

EDIT: Me speel gud.

[Mrbloodworth]

Jumpgate Evolution - AI System: Nuts & Bolts

We've spoken a great deal in interviews and other articles about just how excited we are about Jumpgate Evolution's AI system. It has rapidly gone from being a system intended to solve one or two things, to becoming the tool of choice to address all sorts of interrelated game issues. Although we try to maintain perspective and recognize that employing the AI system is not always the proper solution to a problem, this is truly a case where the excited kid inside each of us tends to burst out and enthuse, "We can make the AI do that! Wouldn't that be great?" It's simply the case that our AI system is turning out to be very capable and versatile, so it's extremely tempting to make quite extensive use of it.
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We began simply, with the AI system's chief task being to populate space. The plan was to make large numbers of AI ships that would travel around the game, performing real tasks in real ways, using a list of available behaviors and incorporating forms of mutual communication. To begin realizing this design, we considered the basic tasks that every player must employ simply to fly her ship around the Jumpgate game universe. Each possible role, be it hauling, mining, piracy, or whatever, was considered in terms of both its unique behaviors and common activities. Each process became an algorithm. Each major type of AI bot, as defined by role, became a class. The behaviors themselves became polymorphic functions inherited by the role-based classes from more generic parent classes, such as "mobile bots" or "stationary bots". As an example, nearly all mobile bots inherit and use a "Travel" behavior, which manages the process of long-range navigation. Likewise, there are common "Dock", "Launch", "Jump", and "Avoid" utility behaviors employed by everything that must move.

The list of behaviors becomes extensive when considering the special activities of each possible role. As an example, a bot simulating a mining vessel will employ a combination of common and unique behaviors to accomplish its task. First, the bot will be created with member data that includes such things as its location and what kind of asteroid it must find to mine. The bot will physically launch as the final step of its creation process. Once the launch algorithm ends, the bot must perform a detection step to see if there are any viable targets in the area. Failing that, it may travel to another location, avoiding collisions with objects along the way, and possibly jumping to an entirely different sector of the game to continue its search. At some point, we will assume for this example that a target match is detected, so the bot will approach the chosen asteroid using a unique mining behavior. Other bots would naturally use a collision avoidance behavior in the vicinity of an asteroid or similar object, but the mining bot instead must cozy up to a rock to do its job. The bot will halt close enough to the asteroid to use its mining equipment, functionally handing off to another behavior that controls the mining process itself. During mining, the bot will perform additional transactions with the servers that handle its inventory changes, much like any player would. Once the bot determines its inventory is full, it will revert to a common travel behavior to some destination to deliver its cargo. Upon arrival at the destination facility, the bot will execute a docking behavior, transfer the ore from member data to the facility's inventory, and be removed from existence by the system.

As can be seen by the example life cycle of a mining bot, even a pretty typical AI object must be able to accomplish a significant number of different things to serve its purpose in the game. The example doesn't even include most of the decision-making variability in the process, nor does it include any interesting interruptions; it's just the dull life of a pretty normal bot.

Interruption events turn out to be the real spice of life for a bot's decision making process, and from the start the AI system was built to make them a centerpiece of its operation. With the exception of collision avoidance, all the interruption events thus far defined for the system either are triggered by, or result from, some form of bot-to-bot communication. Just as with the behaviors, we built a list of types of bot-to-bot interactions, which became a list of message types. The messages function like invitations, "Attack me", "Pirate me", "Help me", and so forth. Every type of bot places specific messages in dedicated regional communications queues. Some types of bots poll these queues at intervals, and if they find an appropriate message type, they pick up the message and change behavior in reaction. A typical example of these interactions looks like this: a hauler bot, representing a cargo ship, jumps in and posts "Attack me" on the local queue, and continues traveling across the sector. An aggressor bot in the sector, representing a hostile alien Conflux, polls the queue, picks up the "Attack me" message, and switches from loitering to a set of behaviors that cause it to locate, fly to, and engage the hauler. The hauler, now interrupted in its travel by the attack, posts a "Help me" message in another queue. A defender bot, representing a factional fighter on patrol, polls the help queue and picks up the hauler's message. It breaks from its patrol behavior and streaks to the aid of the hauler, possibly posting its own version of "Help me" for other defenders to pick up on, gathering a posse. By choosing appropriate values for different polling cycles, we've already seen very exciting, lifelike activity in basic proof-of-concept work on the system. Broad implementation for all cases, though, is not yet completed. We fully expect to continue fleshing out the AI system through release.

The ultimate purpose, however, isn't to create a nifty network of thousands of bots that effectively play the game for us. That would make a delightful AI experiment and does have use as an excellent load testing tool, but ends up doing little for gameplay. The true power of the system will hinge upon tying the already operational message and queueing system into interfaces that players themselves have access to, and bringing the universe to life in ways that let players participate. Ideally, routine player activity will post similar messages to the AI queues for bots to react to, and players will be able to passively or actively perform some kinds of polling actions themselves, with appropriate and equivalent information displays to help them react to and participate in what will have become spontaneous events originated by the AI. This is really what has the development team so terribly excited about the potential represented by Jumpgate Evolution's AI system.

While the basic interlinks between the players' UI and the bots' queues are a significant part of what remains to be implemented, we surely intend to have some of this vast potential realized by release. Imagine that, rather than the defender bot rescuing the hauler, instead the nearby players see a HUD indicator flash with a message: "This is Free Trader Beowulf, calling anybody... Mayday, Mayday.... "*

- Steve "Istvan" Hartmeyer, Programmer

*partial box quote from the original Traveler game, by Marc Miller, (c) 1977, Game Designers' Workshop.

[Sky]

The ultimate purpose, however, isn't to create a nifty network of thousands of bots that effectively play the game for us. That would make a delightful AI experiment and does have use as an excellent load testing tool, but ends up doing little for gameplay.

Verisimilitude.

I've caught some shit in the past for wanting some kind of dedicated AI hardware, and I allow that it's not realistic after seeing the Ageia debacle. Maybe now that multi-core chips are coming out we might get good AI. I'm starting to think we won't get a good vibrant virtual world full of deep interactive AI before I die. That sucks. C'mon, devs. Your graphics are shiny, your sound is surround. But the AI is still like living in a world of autistic, non-functional retards.

[Mrbloodworth]

The ultimate purpose, however, isn't to create a nifty network of thousands of bots that effectively play the game for us. That would make a delightful AI experiment and does have use as an excellent load testing tool, but ends up doing little for gameplay.

Verisimilitude.

I've caught some shit in the past for wanting some kind of dedicated AI hardware, and I allow that it's not realistic after seeing the Ageia debacle. Maybe now that multi-core chips are coming out we might get good AI. I'm starting to think we won't get a good vibrant virtual world full of deep interactive AI before I die. That sucks. C'mon, devs. Your graphics are shiny, your sound is surround. But the AI is still like living in a world of autistic, non-functional retards.

As far as i'm aware, the AI they are talking about is run by a wholly separate server, in addition to the regular line up. In addition, the amount of AI scales with how many people are on line in any given world. What they are attempting to do, is create what you are asking for, at least, in part.

The AI makes the galaxy live, and does affect things like commerce. Example i have read is that if an AI knows a station or other thing is wanting or needing some commodity, it will attempt to buy some, and ship it to that station....Of course, that is, if a player dosn't interrupt it =). So its not just a simple case of the server spawned AI becouse you or someone is now there, and it needed to fill up some space, that AI was already there, and is on a mission of its own...you being present or not. In this way, the "world" will always be changing, and living.

Its also supposed to respond to your hails and what not with responses, depending on what you say to it, and what it happens to be, and what its "Attitude" is set to.

Time will tell.

[slog]

Yes, it's a seperate AI server.

[ajax34i]

The whole "attack me!" "pirate me" seems like a weird way to do it, though.  It would have made more sense to me if the transport bot was just broadcasting its position and the fact that it was a transport bot, and the aggressor bot was looking at the queue and reacting with "Ooh, a transport bot!  I'm gonna attack it!"

Same end result for the bots.  But the outcry from players when they find out that their character is silently broadcasting "attack me!" "pirate me!" to all the bots in a zone will be, I imagine, much bigger than if they found out their character was simply broadcasting its position so that the AI could "see" it with its limited pseudo-senses.

[Mrbloodworth]

The whole "attack me!" "pirate me" seems like a weird way to do it, though.  It would have made more sense to me if the transport bot was just broadcasting its position and the fact that it was a transport bot, and the aggressor bot was looking at the queue and reacting with "Ooh, a transport bot!  I'm gonna attack it!"

Same end result for the bots.  But the outcry from players when they find out that their character is silently broadcasting "attack me!" "pirate me!" to all the bots in a zone will be, I imagine, much bigger than if they found out their character was simply broadcasting its position so that the AI could "see" it with its limited pseudo-senses.

Same result. Just a different way of flagging. Thing is, the AI has to choose to do so.. It may not be on its list of things to do today, and i'm quite sure the wording was really only for the blog.

[tazelbain]

It does seem the AI is reversed (sheep's AI deciding if it OK for wolves to attack), but The Sims should that reversing the AI the works well.

Here it makes sense because if all the AI is in wolf, it has to go down the of all objects and make a determination if its a sheep and if valuable to attack.  Now you doing assessment wolf x objects(sheep or not) times.  Now if you put the asscessment on the sheep-side, the assecessment can be done once accross just the sheep objects and broadcast to wolfs if they have strayed from the shepard.

[Venkman]

I like how that read. Reminds me of other games that have tried the "living world" thing, and I generally find the results to at least be interesting. I always like the idea of worlds that exist and you're just another part of it, albeit slightly more resourceful

[SnakeCharmer]

This really does look like fun.  Not very sticky, but looks like it'd be fun to jump in and out of for some space combat goodness.

No avatars kinda kills it for me, as well as any resemblence of a 'ground' game - whether it's on a planet of another ship/space station.