Does camera speed vary depending on FPS / performance?

Questions
1

We are having testers reporting very slow camera speeds ( seen it myself too at times ). Using the standard UniversalCamera, it seems like the worse the performance, the slower the camera movement becomes. A few people called me crazy but recently its become worse. Am I correct in reading this that FPS is taken into account for the camera speed ?

    public _computeLocalCameraSpeed(): number {
        var engine = this.getEngine();
        return this.speed * Math.sqrt((engine.getDeltaTime() / (engine.getFps() * 100.0)));
    }

This is on desktop with keyboard movement

2

yep it is taken in account:) it will lag but go at the same speed :smiley:

3

But, what does it mean?
Like, is camera speed like 10 m/s then, 10 units or something?
I’ve been playing with this a bit, and I think that

camera._computeLocalCameraSpeed = () => {return camera.speed * this.engine.getDeltaTime()/1000};

actually matches like 1 unit in 1 second. As a bonus, no square root :wink:
Just wondering, additional info appreciated.
(I’m switching 1st and 3rd person camera, trying to keep the same speed)

4

cc @PolygonalSun

5

should prolly turn that / 1000 into a * 0.001. Avoid division as much as possible.

6

Seems there is some space for these improvements in the Babylon source code - https://github.com/search?q=repo%3ABabylonJS%2FBabylon.js+"%2F+1000"&type=code

7

Right, but what’s the idea of

Math.sqrt((engine.getDeltaTime() / (engine.getFps() * 100.0)))

The way I see it,

engine.getDeltaTime()

alone does the trick.
But that’s (mostly) because I assume that both deltaTime and FPS are function of performance alone. If that function is something squared, root may make sense, but I just don’t see it.
Heuristics?
Either way, just trying to make sense of it.

9

If I’m understanding correctly, this line is for adjusting the local camera speed so that frames with a delta time that differs drastically from the average (engine.getFps() will return _fps, which should be the average FPS over time) will scale and reduce the effects of major deviations in frame speed. I will admit, I’m not sure that I fully understand the existence of the sqrt myself though so lemme ask around a bit about it.