FrameTicker

FrameTicker creates an object that continuously loops (“ticks”) on every rendering frame, dispatching callbacks every time it does so.

It works on top of requestAnimationFrame, but with features of its own. It does not provide a polyfill for browsers that don’t support requestAnimationFrame.

FrameTicker is written in TypeScript, but can be used both in JavaScript and TypeScript. In TypeScript, you get the benefit of automatic declarations (auto-completion, “intellisense”).

Installation

Simply install FrameTicker as a module dependency using NPM:

npm install frame-ticker --save

Usage

Import:

// Import (JavaScript ES5)
var FrameTicker = require('frame-ticker').default;
// Import (JavaScript ES6 and TypeScript)
import FrameTicker from 'frame-ticker';

Create an instance:

let ticker = new FrameTicker(); // Create and start, at current browser FPS (60)
let ticker = new FrameTicker(30); // Create at 30fps and start
let ticker = new FrameTicker(30, 15); // Create at 30fps, but with a minimum of 15 calls per second, and start
let ticker = new FrameTicker(NaN, NaN, true); // Creates at paused state

Then, add callbacks using simplesignal events:

looper.onTick.add((timeSeconds, tickDeltaSeconds, currentFrame) => {
    console.log(`Executing for ${timeSeconds} seconds, delta since last tick is ${tickDeltaSeconds}, current frame is ${currentFrame}.`);
});

A typical implementation in games is moving things at a certain speed per seconds. Example:

private function onTick(currentTimeSeconds:number, tickDeltaTimeSeconds:number, currentTick:number):void {
    let speed = 10; // Speed of the box, in pixels per seconds
    box.x += speed * tickDeltaTimeSeconds;
}
looper.onTick.add(onTick);

You can also pause/resume the looper to pause/resume the game loop:

looper.pause();
looper.resume();

Ot change the time scale to make time go “faster” (reflected in timeSeconds and tickDeltaSeconds):

looper.timeScale = 2; // 2x original speed (faster motion)
looper.timeScale = 0.5; // 0.5x original speed (slower motion)

When the maxFPS parameter is used, the looper is not dispatched more that number of times per second:

// Max 30 fps dispatching; will only fire once every other visual frame on a 60fps browser
let looper = new FrameTicker(30);

When the minFPS parameter is used, the looper is always dispatched at least that amount of times per second, regardless of the number of frames:

// Max 120 fps dispatching; will fire twice per visual frame on a 60fps browser
let looper = new FrameTicker(NaN, 120);

Full reference

new FrameTicker(maxFPS:number = NaN, minFPS:number = NaN, paused:boolean = false):FrameTicker

Generate a new FrameTicker instance.

Parameters:

• maxFPS: Desired maximum framerate. Cause onTick calls to be skipped if the desired maximum framerate is lower than the current environment maximum. NaN means no maximum.
• minFPS: Desired minimum framerate. Cause onTick calls to be repeated more than once per frame if the desired minimum framerate is higher than the current environment maximum. Careful when using this, since it can create performance problems in low-performance situations; it can’t magically makes thing faster. NaN means no minimum.
• paused: Whether it’s paused at start or not.

Return:

• A new FrameTicker instance.

updateOnce(callback:(timeSeconds:number, tickDeltaSeconds:number, currentFrame:number) => void)

resume()

pause()

dispose()

currentTick:number

currentTimeSeconds:number

tickDeltaTimeSeconds:number

timeScale:number

onResume:SimpleSignal

Can use .add(f), .resume(f), .removeAll

onPause:SimpleSignal

onTick:SimpleSignal

onTickOncePerFrame:SimpleSignal

License

MIT.