Correct way to use dtime in this situation?

I got things to work, but in a different way, so I am curious what the correct way is to use delta time with multiplication like this. Should have been simple, but it did not work.

ObjectX = ObjectX + speed dt here is basically Object.X + speed*dt or (speed*60)*dt if redoing an older game that used speed that worked at 60 frames per second without using dt.

Now I want to simulate drag so I decrease speed every tick by multiplying it by 0.99

speed = speed*0.99 So what is the correct way to use delta time here?. doing things like 0.99*dt do not work.

Anyway, I got it to work with something like this lerp(speed,speed*0.99,1-0.0999^dt). It does work, but it just seems like a hack that should not really work

Just to add. You have to test it with this new beta feature and run full frames, not v-sync

Actually I should change that. Its should always just be speed*dt.

(object.x+speed*dt)*0.99

That is what I had originally, but in 2 actions

object.X = object.X + speed*dt

speed = (speed*0.99)*dt

Tried a couple of variations and your example, does not work

The second way you wrote it does seem to work at 60FPS, but it does not work at full frame setting. I think 0.99 needs to be dtimed somehow, otherwise you are multiplying by 0.99 twice or three times as fast at full frames setting

Don' know if this is a bug but:

+ System: Every tick

-> System: Set speed to speed×dt

is always 0 independently of the start size of speed.