It is smooth, isn't it?

[illwieckz]

I want to share a feeling, I don't really know how to describe it.

But since some releases, I feel the game extra smooth. I'm not talking about framerate, my hardware had been able to do short frametime and then high framerate for a very long time but I didn't get that feeling before. Also, My screen is still limited to 60fps, so I'm not getting this smoothness feeling from getting more frames being rendered.

My assumption is that the feeling may come from less jittery frame, i.e. frames making themselves to the display with a constant time. Let's imagine you have a 60Hz screen, and the game renders at 200 fps, but every 10 frame, one frame would miss the 60Hz tick rate. You would still get an high framerate but experience frame skip.

I noticed I sometime just move my mouse around and this produces me some satisfaction and this feeds the feeling of the engine being very different (in a much better way) than before. I just like to move my camera around and move the player around and appreciate the smoothness.

Does it happen to you too?

I wonder if this feeling comes from some a specific optimisation we did, or the whole collection of the one we did. Since I experience the difference even when moving around as a spectator in a simple map like plat23, I highly suspect the very stupid IPC round trips, useless cvar read from local-only variable and the lack of game-side cvar caching were the cause of the non-smoothness I experience to be now gone.

Do you experience a similar feeling?

[killing time]

IIRC Ishq believes the opposite, that recent versions are not smooth any more

[illwieckz]

Quoting IRC:

Code: Select all

<Ishq> indeed
<Ishq> there was a time where the game was so buttery smooth i had tears in my eyes
<Ishq> Like the animations were crisp
<Ishq> but now I see jank in the animations, like they stutter
<Ishq> it might also just be normalmap aliasing tho
<Ishq> which bugs me when i look at models and see that in the bg

We don't talk about the same thing. It's possible that model animations were smoother before, but the smoothness I talk about can be experienced with or without models around. I would say it's not the smoothness of what you are looking at, but the smoothness of looking around at things, including the non-animated world.

Maybe a part of what I talk about is what people call “input lag” or things like that. The “input lag” is misnamed in my opinion, in French we call this “retard d’affichage”, so “display lag”, it makes more sense this way. But the main cause of my feeling seems to be frame time consistency. It's possible that this contributes to the feeling. But I guess many things contribute to the improvement.

The most simple way to experiment what I talk about is to just be a spectator in some map (example plat23 outdoor, there is no model to look at there!) and just move the mouse in circles.

I guess what I experienced was something like that:

Code: Select all

     |     |     |     |     |     |     | Screen frames (7 frames)

[    ][    ][    ][    ][    ][    ][    ] Screen frametime

| |||    ||        |||||       |||||| |||  Rendered frames (19 frames)

     |     |           |           |     | Displayed frames (5 frames)

Actually this is not only a feeling, we could see that exact lag being displayed in Gallium HUD framerate graph, and we could also see the huge Cvar lag in Orbit profiling graph.

In that theoretical example, one can see how a game would render a framerate almost 3 time higher than the screen while displaying a framerate lower than the screen. If I extrapolate that graph, for a 60Hz screen, the engine would render 154 frames per second but only display 42 frames, displaying a glorious 154 fps on the UI but giving to the player a very bad 42 fps in reality and then a poor gaming experience.

In the GPU compatibility matrix I'm accustomed to add an extra note named fakefps for describing systems that report high frame rate but the experience doesn't match what is reported. I write down fakefps when just by moving my mouse in circles and flying around as a spectator the frame skip is very obvious, much more laggy than what I always experimented before the new “smoothness” I talk about.