c19aa5939d
# Objective - Add Time-Adjusted Rolling EMA-based smoothing to diagnostics. - Closes #4983; see that issue for more more information. ## Terms - EMA - [Exponential Moving Average](https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average) - SMA - [Simple Moving Average](https://en.wikipedia.org/wiki/Moving_average#Simple_moving_average) ## Solution - We use a fairly standard approximation of a true EMA where $EMA_{\text{frame}} = EMA_{\text{previous}} + \alpha \left( x_{\text{frame}} - EMA_{\text{previous}} \right)$ where $\alpha = \Delta t / \tau$ and $\tau$ is an arbitrary smoothness factor. (See #4983 for more discussion of the math.) - The smoothness factor is here defaulted to $2 / 21$; this was chosen fairly arbitrarily as supposedly related to the existing 20-bucket SMA. - The smoothness factor can be set on a per-diagnostic basis via `Diagnostic::with_smoothing_factor`. --- ## Changelog ### Added - `Diagnostic::smoothed` - provides an exponentially smoothed view of a recorded diagnostic, to e.g. reduce jitter in frametime readings. ### Changed - `LogDiagnosticsPlugin` now records the smoothed value rather than the raw value. - For diagnostics recorded less often than every 0.1 seconds, this change to defaults will have no visible effect. - For discrete diagnostics where this smoothing is not desirable, set a smoothing factor of 0 to disable smoothing. - The average of the recent history is still shown when available.
49 lines
1.7 KiB
Rust
49 lines
1.7 KiB
Rust
use crate::{Diagnostic, DiagnosticId, Diagnostics};
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use bevy_app::prelude::*;
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use bevy_core::FrameCount;
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use bevy_ecs::system::{Res, ResMut};
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use bevy_time::Time;
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/// Adds "frame time" diagnostic to an App, specifically "frame time", "fps" and "frame count"
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#[derive(Default)]
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pub struct FrameTimeDiagnosticsPlugin;
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impl Plugin for FrameTimeDiagnosticsPlugin {
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fn build(&self, app: &mut bevy_app::App) {
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app.add_startup_system(Self::setup_system)
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.add_system(Self::diagnostic_system);
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}
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}
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impl FrameTimeDiagnosticsPlugin {
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pub const FPS: DiagnosticId = DiagnosticId::from_u128(288146834822086093791974408528866909483);
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pub const FRAME_COUNT: DiagnosticId =
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DiagnosticId::from_u128(54021991829115352065418785002088010277);
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pub const FRAME_TIME: DiagnosticId =
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DiagnosticId::from_u128(73441630925388532774622109383099159699);
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pub fn setup_system(mut diagnostics: ResMut<Diagnostics>) {
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diagnostics.add(Diagnostic::new(Self::FRAME_TIME, "frame_time", 20).with_suffix("ms"));
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diagnostics.add(Diagnostic::new(Self::FPS, "fps", 20));
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diagnostics
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.add(Diagnostic::new(Self::FRAME_COUNT, "frame_count", 1).with_smoothing_factor(0.0));
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}
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pub fn diagnostic_system(
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mut diagnostics: ResMut<Diagnostics>,
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time: Res<Time>,
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frame_count: Res<FrameCount>,
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) {
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diagnostics.add_measurement(Self::FRAME_COUNT, || frame_count.0 as f64);
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let delta_seconds = time.raw_delta_seconds_f64();
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if delta_seconds == 0.0 {
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return;
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}
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diagnostics.add_measurement(Self::FRAME_TIME, || delta_seconds * 1000.0);
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diagnostics.add_measurement(Self::FPS, || 1.0 / delta_seconds);
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}
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}
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