How to keep velocity while being in air ?

[thorn needle]

So, i'm currently making a fast fps movement controller (something similar to Quake), and i'm struggling on how to keep the velocity momentum while being in air, after pressing a direction input.
Here's my movement code part :

var input_dir = Input.get_vector("left", "right", "frontward", "backward") 
var direction = (cameraHolder.basis * Vector3(input_dir.x, 0, input_dir.y)).normalized()
if is_on_floor():
        if direction:
            velocity.x = lerp(velocity.x, direction.x * moveSpeed, moveAcceleration * delta)
            velocity.z = lerp(velocity.z, direction.z * moveSpeed, moveAcceleration * delta)
        else:
            velocity.x = lerp(velocity.x, direction.x * moveSpeed, moveDecceleration * delta)
            velocity.z = lerp(velocity.z, direction.z * moveSpeed, moveDecceleration * delta)
elif !is_on_floor():
        if direction or !direction: 
            velocity.x = lerp(velocity.x, direction.x * moveSpeed, airControlForce * delta)
            velocity.z = lerp(velocity.z, direction.z * moveSpeed, airControlForce * delta)
        
    move_and_slide()

So, does anyone know how i can do that ?

How to keep velocity while being in air ?

[gritty badge]

maybe use move_toward() instead of lerp()

move_toward would be linear acceleration though, so do consider that

also you don't need the elif !is_on_floor(), since it's guaranteed if the if is_on_floor() evaluates as false

also direction or !direction always returns true as well

[thorn needle]

I know that, it's just that i find it more clear if it's written this way

And yeah, you're right, using move_toward allow to keep the velocity momentum while being in air

[gritty badge]

what is the behaviour you want if no inputs are pressed?

because right now, your direction or !direction means it's always approaching direction

if and no diections are pressed, that direction is 0,0

[thorn needle]

That the point
If direction equals false, that mean that direction equals 0.0

[thorn needle]

The player character go from the current speed to 0, with a velocity momentum value

[gritty badge]

then yea, try move_toward() instead of lerp

[thorn needle]

Yeah, i tried it, and it works well
But just, what are the actuals differences between lerp and move_toward ?
Because i thought it was just that lerp was more fluid than move_toward, but it seens that theres's way more than that

[gritty badge]

lerp is percentage based

which creates exponential movement (looks good in most cases)

move_toward is exactly that: move_toward linearly

issue with lerp: it's percentage based

lerp(a, b, t)

a is value if t = 0
b is value if t = 1
t is percentage between the two

t = 0.5 gives you the exact middle

if you reuse the result in a lerp for a, you can visualize the change

say we use lerp(0, 1, 0.5)

returns 0.5

lerp(0.5, 1, 0.5) = 0.75

move_towards moves until it hits the value

move_toward(0, 100. 10) = 10
move_toward(10, 100. 10) = 20
move_toward(20, 100. 10) = 30
etc.

[thorn needle]

Oh ok
But using move_toward cause an annoying issue in my code, it drain the air control value

[gritty badge]

wdym drain?

[thorn needle]

If the air control value is high, the velocity momentum is ridiculously low
But if the air control value is low, it's like you have to force yourself to move in air, it's not fluid at all

[gritty badge]

that makes sense actually

[thorn needle]

Yeah i know, but that not what i want

[gritty badge]

you are using the same airControlForce for both acceleration and decceleration

hence why i asked you "are you sure you want direction or !direction?"

        if direction:
            velocity.x = lerp(velocity.x, direction.x * moveSpeed, airControlForce * delta)
            velocity.z = lerp(velocity.z, direction.z * moveSpeed, airControlForce * delta)
        else:
            velocity.x = lerp(velocity.x, direction.x * moveSpeed, moveDecceleration * delta)
            velocity.z = lerp(velocity.z, direction.z * moveSpeed, moveDecceleration * delta)```

you prob want this or smt

maybe replace moveDecceleration with AirDecceleration

or like drag, or smt

[thorn needle]

Yeah, you're right, i was currently correcting my stuff actually 😅

Here's my modifications :

elif !is_on_floor():
    if direction: 
      velocity.x = lerp(velocity.x, direction.x * moveSpeed, airControlForce * delta)
      velocity.z = lerp(velocity.z, direction.z * moveSpeed, airControlForce * delta)
    else:
      velocity.x = move_toward(velocity.x, direction.x * moveSpeed, delta)
      velocity.z = move_toward(velocity.z, direction.z * moveSpeed, delta)

[gritty badge]

I would personally use different variables to make it more customizable

oh yea, also forgot to replace the lerps in mine

[thorn needle]

Yeah you're right about that too

Just, if i'm not wrong, this variable will have to be related to the moveSpeed variable

[gritty badge]

if your game needs that for balance, then yea

physics are just however you want them to be in games

[thorn needle]

Yeah, well for a more juicy controller, i think it's better to keep a velocity related to the last current speed, so it's probably better to have a variable for that related to the velocity