Smooth Movement Question

[ultdoomer]

Can someone explain to me exactly what smooth movement does (on a technical level while using layman's terms)?

[myk]

More than doing anything, it's the result of something. Movement isn't smooth when it's irregular, shaky and choppy. Either because the player is unaccustomed to the controls, nervous, uncoordinated, or uses a mouse sensitivity setting he can't manage well.

[ultdoomer]

ultdoomer said:

on a technical level

I figured that's what it did from a visual standpoint. But how is movement altered when it is on (for example, what causes the lag in PrBoom when you have smooth movement on in slow-motion)?

[Grazza]

OK, so you're referring to one of the optional features, available for demo playback only, of Prboom-plus.

I presume what it does is, in terms of the camera's viewpoint, spread any large-angle turns by the player over a larger number of gametics than was actually the case in the demo. For instance, if the player made a 45 degree turn in gametic number x and no turns in the two gametics on either side, then the program might make the camera turn through 5 degrees in gametic x-2, 10 degrees in gametic x-1, 15 degrees in gametic x, 10 degrees in gametic x+1 and 5 degrees in gametic x+2. This is just the camera though; the player's actual orientation (for the purpose of firing and running) is the same as when the demo was recorded - obviously, since the demo would desync otherwise.

I should add that I am just plucking these numbers out of thin air, and relying on supposition here. (And I might be dead wrong about earlier gametics being affected at all by turning in later ones.) For actual details (and for how it depends on the variable degree of smoothing), you'd need to look at the code or ask Andrey, but my understanding of the feature is that it works something like this.

It's not a feature I have enabled myself - if a demo is jerky, I'd rather see this myself, and only admire smoothness when it was genuinely achieved by the player. But as an optional feature, it's kind of interesting.