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OHZI Components

Performance Controller

  • Disables optional features, and raises or lowers the DevicePixelRatio, depending on the current frames per second (FPS).
  • Class. Create one with new.

Rules

On every frame, once the breathing window has passed:

Condition Action
FR < 30 & opt_to_disable Next optional feature in the list gets disabled
FR < 30 & NO_opt_to_disable DPR reduced by 0.25, to a min of 0.75
30 ≤ FR < 60 & threshold disabled & DPR > 1 DPR reduced by 0.25 and threshold enabled
FR ≥ 60 & threshold disabled DPR increased by 0.25, to a max of 1.25 × window.devicePixelRatio (min 1)

FR => framerate, FPSCounter.avg

DPR => Device Pixel Ratio, settings.dpr

  • Framerate is the average of 5 samples, each 1 second long.
  • Threshold enabled means the framerate is in the accepted range. It stops DPR increases and the 30 ≤ FR < 60 reduction, but FR < 30 still acts. Once enabled it stays enabled.
  • A breathing window is set, checking for performance_t > 2 on each frame. This gives the app 2 seconds to stabilize. It restarts after every action and when the window regains focus.
  • The two FR < 30 actions also reset the FPS samples to 60.

Methods

  • init(omath, settings, graphics, time, oscreen, fps_counter): Initialize component.

    • omath: OMath from ohzi-core.
    • settings: An object with a numeric dpr that the controller reads and writes. In the boilerplate, Settings from app/js/Settings.ts.
    • graphics: Graphics from ohzi-core. Each DPR change calls graphics.on_resize() with the new DPR and the current OScreen position and size.
    • time: Time from ohzi-core.
    • oscreen: OScreen from ohzi-core.
    • fps_counter: The FPSCounter singleton. Call FPSCounter.init(Time) first.

    Also binds window focus and blur.

  • on_focus_in(): Starts performance check. Bound to window focus. (private)

  • on_focus_out(): Stops performance check, including FPS counting. Bound to window blur. (private)

  • add_optional_features([...]): Add features that can be disabled if performance is too low. It receives an array of objects that have to implement the method disable_optional_feature(). They are disabled one at a time, in array order, and never re-enabled.

  • update(): Should be called in an update method. Also calls fps_counter.update(), so don't call that yourself.

Properties

  • threshold: Whether the threshold is enabled.
  • optional_features: Features added with add_optional_features().
  • performance_t: Seconds since the last action.

Example

import { Graphics, OMath, OScreen, Time } from 'ohzi-core';
import { FPSCounter, PerformanceController } from 'ohzi-components';
import { Settings } from './Settings';

FPSCounter.init(Time);

const performance_controller = new PerformanceController();
performance_controller.init(OMath, Settings, Graphics, Time, OScreen, FPSCounter);

performance_controller.add_optional_features([
  { disable_optional_feature: () => bloom.disable() },
  { disable_optional_feature: () => particles.hide() }
]);

// In your update loop
performance_controller.update();

Notes

  • In the current ohzi-core, Graphics.on_resize() sets OScreen.dpr but doesn't call setPixelRatio(), and three.js setSize() sizes the canvas with the pixel ratio set at Graphics.init(). So DPR changes don't change the canvas resolution yet.