22 replies to this topic

[Felicitatem Parco]

There's a time in the GDC gameplay trailer video (34 seconds) where a fast-moving Jenner is running along a gulley and approaches the walls of said gulley... and begins to sail right up the sloped side as if his linear momentum vector was instantly transfered to vertical momentum without the Mech even missing a step. It simply bolted right up the hill as if the valley floor and the hillside were just a continuous flat plane.

It was way too smooth. I will concede, though, that the height it climbed was not very high and it did sem to slow down somewhat as it went up. The problem, to me, was that the Mech should have stumbled a bit form the huge change in direction it just assumed (nearly linear to nearly vertical). The way I see it: wheeled vehicles can coast right up a curved slope like what you see in the video without "breaking stride" because it's rolling on wheels; a walking BattleMech would have to expend huge amounts of energy to lift itself uphill step-by-step because it has no gliding wheels with ball bearings on which to bear the force of transferring forward momentum to vertical momentum.


Was that just an infrequent artifact that happened to be in the video, or will Light Mechs just transfer their linear momentum with super-high levels of efficiency into vertical momentum like that? I have to assume that there are some engine-specific quirks that can have unavoidable effects on games, and this might be just that... or it could be just an infrequent artifact that happened to be in the video and it won't really represent general gameplay.

I have spoken at-length with one of my friends who does character animation for a career and she always tells me about how difficult it is to program animations that have feet properly tracking with the character object itself. This seems to be an occasion where a massive change in height of the environmental features took place in a narrower-span than the width of the Jenner's legs, and that could explain the quirky smooth climb.

Edited by Prosperity Park, 03 May 2012 - 11:26 AM.

[Adridos]

Hopefully just a placeholder.

[Orzorn]

If you watch the final part of the video where the Hunchback goes down the hill, it speeds up temporarily.

So it seems that momentum is created or lost, but perhaps the naturally high speed of the Jenner made it seem like it didn't lose any speed.

[Ursus_Spiritus]

The mech was using jump jets?

How skilled is the pilot?

If skilled enough the Mech becomes an extension of your self, in movement, body language and similar traits.

Same goes for suit of armor, even clothing.

Granted the scale/mass are significant, just seems that fluidity of movement would come naturally over time as one becomes adept at use of this external physical representation of one's being and thought process.

Something akin to a fighter pilot, race car driver etc. Moves are jerky and "rough" starting out, even studying martial arts but after time it becomes "Second nature".

Your mind and body and by extension the exoskeleton/armor/mech become as fluid, aside from design restrictions but one would learn how to manage those to his/her advantage.

Also assuming that the JJs just instancly fire, or if they gradully increase thrust.

If the unit is walking/running and climbs an elevation, more so that would be fluid body motion/though process?

I am just throwing "what if's"

[Monky]

I would chalk it up to the benefits of having legs... you're not using a single transmission with an internal combustion engine to pull that sustained power off, but rather myomer powered legs using a fusion plant for energy.

[Felicitatem Parco]

monky, on 03 May 2012 - 11:01 AM, said:

I would chalk it up to the benefits of having legs... you're not using a single transmission with an internal combustion engine to pull that sustained power off, but rather myomer powered legs using a fusion plant for energy.

The way I see it, it's not energy-plant but ambulation method that matters: wheeled vehicles can coast right up a curved slope like what you see in the video without "breaking stride" because it's rolling on wheels; a walking BattleMech would have to expend huge amounts of energy to lift itself uphill step-by-step because it has no gliding wheels with ball bearings on which to bear the force of transferring forward momentum to vertical momentum.

Edited by Prosperity Park, 03 May 2012 - 11:14 AM.

[Monky]

That's my point though, we're capable of short uphill movement with little/no decrease in speed with a relatively low power engine and transmission compared to fusion powerplants (for example, M1 Abrams tank which weighs much more than a Jenner).

Now, the roadwheels and high traction with low resistance to the transmission make it more efficient for that manuever, but for distances in the video, I don't think it's beyond the pale. Now, if it where a Catapult or an Atlas... yeah, those things weigh as much or more than current tanks, and I don't see their powerplants allowing them to just go up an incline at full speed, but we'll see.

Edited by monky, 03 May 2012 - 11:28 AM.

[Grithis]

Addressing the stumble, I've worked with industrial machinery for the better part of 2 decades. You'd be amazed at the feats the most unassuming machine can just shrug off. A metal coiler at my workplace, (about the size of a kitchen trashcan), does the exact same job with .616 gage metal as it does with .125 gage. It doesn't strain. It doesn't hesitate. It makes 400 feet of hardened aluminum more than half an inch thick into a nice tightly packed coil without missing a beat.

Now Battlemechs, they're military grade. Designed to handle extreme amounts of punishment under any concievable condition. Slowing down uphill, maybe. But to say that it should stumble would be to say that it's legs would strain under little more than it's own wieght. For a machine that's designed to jump 150 meters and generally carry itself through the roiling hell of a war zone, lifting itself up an incline is a small feat.

[GoLambo]

This question really peaked my interested and drove me to look at this problem. Assuming enough traction to not just slide off the dirt right away, if a grade doesn't shorten your stride a great deal you would actually have basically no problem climbing it, and almost no loss of speed assuming you aren't strapped for power. And fusion engine that handles mega joule level lasers does not suggest a power problem. Battlemechs actually shouldn't slow down over most grades!

[Thomas Hogarth]

Let's look at this two different ways:

1: The lore. The lore explicity states that going over rough terrain or terrain with altitude differences (both up and down, interestingly) will make a ground-based vehicle (be it 'Mech or otherwise) go slower. I could get on board with an increased downward speed, but not slowing down going up is counterintuitive.

2: Balance and tactical diversity. If a 'Mech is allowed to travel over broken or altitude-changing terrain at the same speed as flat terrain, there is no reason to use open areas of the map. However, if terrain slows your 'Mech, then you're left with a more difficult tactical decision; do you use broken terrain that will reduce your speed as much as half of normal to gain the advantage of being far more difficult to hit, or do you take a risk by using flat, open terrain to travel quickly to a hotspot, knowing such action will leave you more open to fire? Without this balance, open areas would just be silly to use.

[Felicitatem Parco]

If you push a wagon toward a steep hill, it will roll toward the hill, then soar right up the hill by converting its kinetic energy into potential energy. SOme energy will be lost by friction acting upon the wheel bearings and the energy needed to change the direction of travel... but it will climb the hill seamlessly.

If a Mech runs to a hill and starts climbing, it has to use leg actuator strength to gain every meter of height it climbs; it can't simply "roll uphill" and convert its kinetic energy into potential like a wheeled cart. The Mech has to use leg strength to force the change in direction of travel. So, even though it carries its momentum with it, the legged Mech has to use it's own strength to change from traveling in a straight line to traveling up a hill.

A Jenner running at 100kph cannot just shoot up a 45 degre hill at full speed because that would require the amount of leg strength/force needed to accelerate from Zero to about 60kph instantly. A Mech would stumble under that situation.

Edited by Prosperity Park, 03 May 2012 - 05:07 PM.

[GoLambo]

Prosperity Park, on 03 May 2012 - 05:02 PM, said:

A Jenner running at 100kph cannot just shoot up a 45 degre hill at full speed because that would require the amount of leg strength/force needed to accelerate from Zero to about 60kph instantly. A Mech would stumble under that situation.

The funny thing about legs is that they can do that. When you run, how much energy do you think you spend accelerating compared to sustaining? You're looking at a crazy long torque arm here, and one that's a lot more efficient than a wheel. Instantaneous acceleration is a common feature of the animal kingdom, to say nothing of fusion powered robots.

[Felicitatem Parco]

Try runing at full speed in a straight line using all of your leg strength, then approach a sudden, steep hill and run up that hill at full speed without using any extra leg strength... you will faceplant because the first step you take on the up-hill portion of the hill climb will require more strength than you are capable of producing in order to maintinan both your maximum rate of travel plus the height-gain.

Once you change from going in a straight, level trajectory to an upward trajectory, you have to expend energy to accelerate upward. Wheeled vehicles just trade kinetic energy for potential energy by transfering the force of acceleration onto their suspension and wheel bearings - they roll uphill while gently slowing down. Mechs have to provide that energy from their reactor and leg musculature because they STEP uphill, they don't roll... and if you're already running at full speed then you don't have any extra leg strength remaining to lift yourself up several meters with each step while maintaining max linear velocity.

You could say "Well, the Mechs will simply slow down as they go uphill!" but they can only do that if they change their running stance from long strides to tall steps, and changing your stride from long strides to tall steps when you're already moving at 100kph and using all your strength means you're going to be moving faster than your stride dictates.. and you'll fall over forward, on your face, just like a runner who tries to sprint up stairs without both allowing himself to slow down or using any extra energy in the process of transitioning from flat-and-level to going upstairs: it's futile.

Edited by Prosperity Park, 05 May 2012 - 09:20 AM.

[Karyudo ds]

Funny thing, if I try running up a hill from a full speed run I can becomes exhausted causing me to slow down. A machine doesn't get tired like that so telling a person to try something so that you could apply it to the physics of an inorgangic machine doesn't make sense at all to me. It could take more work to do it but unlike your body it could be specifically designed to do that, an advantage your body lacks.

Overall I'm not even sure why we're examining animation from what is basically an alpha WIP. Normally that receives plenty of tweaks (though I guess we're looking at physics as well but same deal).

On a side note this is exactly how Mechcommander worked. Mechs didn't lose speed uphill or gain it downhill while other vehicles did both. Either for variety or that the mechs were thought to be designed to compensate for the power demand that quickly and careful going down.

Then again you're arguing about technology we won't see for 1035 years or so and the Bigdog can already walk and keep itself upright creapily organically.

[Felicitatem Parco]

I'm not talking about endurance running where the powerplant in question has any relevance. I'm talking about those first 3 steps you take when transitioning from flat-and-level to really-steep-slope.

Try it yourself: sprint toward a flight of steep stairs at full speed, I mean 100%, "There's an angry bear chasing after me!" effort, and then run up those stairs without falling on your face. Do what the Jenner did in the GDC Gameplay Trailer at exactly 34 seconds. You only see it for a fleeting second, but the jenner Shoots up a small slope as if it were a car rolling up hill; It certainly didn't "step" uphill, it "glided" uphill.

Edited by Prosperity Park, 05 May 2012 - 06:01 PM.

[Helmer]

If you skip to 2:25 of this video and watch, around the 2:28 mark the Hunchback hits a slight incline and slows down considerably. I do not believe this is the pilot intentionally slowing his 'mech down, but a reaction to the terrain.

Right before that segment of the clip ends, you can see the throttle being set back to the maximum it can go (Light blue highlight) and the 'mech starting to accelerate as it crests the hill.



Cheers.

[Aelos03]

Prosperity Park, on 05 May 2012 - 05:58 PM, said:

I'm not talking about endurance running where the powerplant in question has any relevance. I'm talking about those first 3 steps you take when transitioning from flat-and-level to really-steep-slope.

Try it yourself: sprint toward a flight of steep stairs at full speed, I mean 100%, "There's an angry bear chasing after me!" effort, and then run up those stairs without falling on your face. Do what the Jenner did in the GDC Gameplay Trailer at exactly 34 seconds. You only see it for a fleeting second, but the jenner Shoots up a small slope as if it were a car rolling up hill; It certainly didn't "step" uphill, it "glided" uphill.

i watched and cant see anything wrong too me it looks le it pass by hill, and later in video i saw from cockpit when it climbs hill you see how it slows down alot.

[Felicitatem Parco]

Aelos03, on 05 May 2012 - 06:38 PM, said:

i watched and cant see anything wrong too me it looks le it pass by hill, and later in video i saw from cockpit when it climbs hill you see how it slows down alot.

The very moment I'm speaking of is when the Jenner starts going uphill right when the scene changes. I mean, the sceen changes *exactly* as the Jenner was doing what I'm complaining about; that's why it's only visible for a fleeting moment.

I don't mean to be a fourletterword about it, but it's just an example of a Mech acting as if it were a computer model that glides along a path and the character movement animations merely exist to make it seem as if the legs are what's dictating the direction and speed of travel... and that's exactly what it is. The Mech models dip, dive, run, and bob around, but in reality it's not the traction of the feet against the ground or the strength of the myomer that makes a BattleMech move, it's the software programming. I feel that Mechs should not be able to traverse sharp slopes that require long, tall leg movements that are mechanically impossible given the Mech design. In this example, I think it was just a case of a Mech acting like a wheeled vehicle due to various factors (natural limitations of the software; the quantity of programming resources available; time constraints; etc.).

I was just hoping it's either an artifact of Beta builds or something that's not going to be a regular occurance in-game. If it's unavoidable due to some technical/human factor, then it's okay, too.

Edited by Prosperity Park, 05 May 2012 - 07:19 PM.

[Tannhauser Gate]

The pilot has the "walk up vertical walls like a freakin vampire" module. Duh.

[Felicitatem Parco]

This is the moment I am talking about. Watch it at 34 or 35 seconds, the Jenner will shoot up this slope like he's in a wheeled vehicle. The legs don't justify that quantity of upward travel. He takes one step and gracefully leaps up several meters without changing his stride by converting linear kinetic energy into potential energy as a vehice or a bowling ball would have done it. Mechs can't do that... Mech's can't use their kinetic energy to change directions of travel... sure, they can carry it with them after the change directions but without ball-bearings or wheels, they can't use that kinetic energy to perform the work of changing direction. That is why it should have face-planted.

Edited by Prosperity Park, 05 May 2012 - 07:36 PM.