25 replies to this topic

[Der Geisterbaer]

CraneArmy, on 15 February 2018 - 08:32 PM, said:

in terms of physics, deceleration isnt a thing at all.

It certainly is a thing in terms of phyisics as well.

CraneArmy, on 15 February 2018 - 08:32 PM, said:

acceleration is a vector quantity, meaning that its a direction and an amount.

Indeed ...

CraneArmy, on 15 February 2018 - 08:32 PM, said:

Any change of speed or direction would be considered acceleration in the direction the accelerating force is being applied, regardless of the object's velocity.

Not quite right. I'll try to make an example that explains why even a vectorized force with a negative sign can and will exhibit both accelerating and decelerating properties that physics certainly do recognize as such:

For purpose of my example let's use the gravitational force of Eath with its rounded value of 10m/s² and its fixed direction "downwards" to the center of the Earth. Since coordinates that are used for describing a vector can be set rather arbirtrarily with regards to which axis direction is positive and which is negativ let's actually make that a -10m/s². We'll also ignore stuff like air friction.

Now as part of the example consider a ball being shot perpendicularly to the Earth into the sky - in other words "straight up" - at a speed of 20m/s ... or whentrying to express that as a vectorized quantity: a velocity of 20m/s in said "upward" direction. Since that velocity is not large enough to escape the Earth's gravitational field the ball will - more or less - go straight up until it has lost it's initial speed (and velocity) and then fall back to Earth at an increasing velocity until it actually hits the ground ... all due to the constantly involved acceleration of -10m/s².

The actual movement is split in three stages:

1. A decelerated movement from its initial velocity of 20m/s down to 0m/s while traveling upward. It'll reach maximum height in relation to Earth's surface after 2s.

2. A very short point in time where the ball actually doesn't move at all at that 2s marker. The -10m/s² however is still in effect at that point.

3. An accelerated movement from 0m/s to once again 20m/s until it hits ground after another 2s.

So even in physics deceleration does have an actual meaning.

I certainly won't start now going into stuff like inertia, frame of reference or acceleration forces that occur perpendicular to the current direction of movement

[Khobai]

physics professors often tell their students deceleration isnt a thing because they want their students to think of everything in terms of opposing forces and vectors.

but the term deceleration still has to exist to clarify what exactly is being said. you cant just say "acceleration" and expect someone to know if you mean its speeding up or slowing down.

Quote

Except it wasn't.
It just slows down.

It doesn't accelerate backwards.


As it was B. You decelerate to slow down.
You accelerate to go faster (in EITHER direction when stopped or to increase speed in a given direction; the "acceleration" quirk/skill node doesn't apply when slowing down as that's where the deceleration quirk/node kicks in.)

yeah what confused me is I tested it in game and my mech accelerated in reverse slower than it accelerated forward

so I thought it used the deceleration value when going in reverse

but now im thinking it uses the acceleration value but applies a modifier to it, just like it does with reverse top speed

I guess PGI doesnt do everything wrong

Edited by Khobai, 16 February 2018 - 03:36 PM.

[CraneArmy]

Der Geisterbaer, on 16 February 2018 - 03:07 PM, said:

I certainly won't start now going into stuff like inertia, frame of reference or acceleration forces that occur perpendicular to the current direction of movement

reference frames.
here is where we get the ambiguity.
because depending on the reference frame, you may appear to be accelerating to me. Even if you appear to be "decelerating" locally.

[Koniving]

Khobai, on 16 February 2018 - 03:29 PM, said:

yeah what confused me is I tested it in game and my mech accelerated in reverse slower than it accelerated forward

so I thought it used the deceleration value when going in reverse

but now im thinking it uses the acceleration value but applies a modifier to it, just like it does with reverse top speed

I guess PGI doesnt do everything wrong

I had started with the explanation that its a percentage and then perhaps reverse and forward accelerations were different (which would make great sense), but as I got started I went to get the acceleration rates.

The stats screen for the mechs show that it uses one acceleration rate for both or only shows a single acceleration. Also the deceleration rate is SIGNIFICANTLY faster... at least on a Shadow Cat with no skill tree; which if deceleration also gave us reverse acceleration would basically be like warp drive since it is around 1.75x faster than acceleration). But to those whom are only just joining and reading this without reading my past posts, yes I know deceleration doesn't give reverse acceleration.

The only remaining explanation, is that "pause" the mech does between going forward, stopping and going in reverse. Perhaps the moment it takes to shift from forward to reverse might have given you that sensation of it being slower?
This is a relic that cannot be helped of the server authority (I think you were around for the first year, right? I know Fupdup was), anyway it was kinda bad back then especially if the ping was high, you'd think the mech just froze in place.

Anyway... Why not compare a stationary to forward and then stationary to reverse acceleration and see if it still seems to be slower in reverse? (that is if you care, I'm not saying "you gotta do this"). Alternatively I recall of a way to switch from forward to reverse acceleration with a single key, at the same percentage of power (50% = half speed either way, 100% = full speed either way).

As for what I'll be doing..

Spoiler

I had an idea for the hypothetical thread for how to translate slips, skids, and sharp turn pilot skill checks into real time for a BT sim without resorting to an RNG, and how it might be visualized in animation...

Also need to check something about how that pilot check actually works, because it'd seem really unfair to need to slow down to say 50% speed as a slow mech if a fast mech had to slow down to 50% speed to prevent that slip on asphalt. Don't suppose you could short cut my looking into that? I rely pretty heavily on Megamek to see rules in action and it doesn't always explain how it works. I'll be checking Citytech first, then probably expanding out from there.

Had the idea yesterday and lamented the fact that my from-scratch 3D models are not ready to use for a demonstration, but who said the demo had to use a mech to show the intention? Long as it's something bipedal and pose-able/animated.

(An extreme example of the base idea is found in the Jenner of this animation. Too quick, too gundam-like, but skidding as the mech forces a [relatively] rapid change in direction really puts forth the weight, the power, and the speed of these machines. Capturing that power of weight can go a long way for immersion as opposed to the insta-stop and weightless turns that MWO and some past mechwarrior games have had.)

Edited by Koniving, 16 February 2018 - 06:43 PM.

[Chris Lowrey]

Koniving, on 16 February 2018 - 06:36 PM, said:

Also the deceleration rate is SIGNIFICANTLY faster... at least on a Shadow Cat with no skill tree

Weight is a factor when it comes to deceleration. So high agility values + Light tonnage will see this value placed very high. It is not like this for all 'Mechs.

[Koniving]

I figured as much.