Struct FrameRate 

pub(crate) struct FrameRate {
    pub(crate) samples: VecDeque<f32>,
}

The frame rate the windowed shell reports, as a component so the panel that displays it and the loop that measures it share one value.

It lives in the world like any other behaviour state rather than being captured by the panel’s closure: a panel may run several times in one frame when egui redoes a layout, and a panel must not reach for its own UiPanel, so the measurement belongs in a sibling component.

Fields

samples: VecDeque<f32>

The frames measured so far, capped at FrameRate::WINDOW.

A sliding window rather than a running mean: a scene that stalls once should not drag the reading down for the rest of the session, and a rate that has just changed should show up within a few frames.

Implementations

impl FrameRate

pub(crate) const WINDOW: usize = 60

How many frames the reading averages over.

About a second at 60 Hz: long enough that the number does not flicker with every frame, short enough that a change is visible promptly.

pub(crate) fn push(&mut self, delta: f32)

Record one frame’s duration, in seconds.

pub(crate) fn mean_seconds(&self) -> Option<f32>

The mean frame time over the window, in seconds, or None before any frame was measured.

pub(crate) fn text(&self) -> String

The reading as "60.0 fps · 16.7 ms".

The frame time is shown next to the rate because the two answer different questions: the rate is what a display is judged against, while the milliseconds are what a budget is spent in.

Trait Implementations

impl Default for FrameRate

fn default() -> Self

Returns the “default value” for a type.