Tweens

Tweens

Animating properties over time in Phaser 4 -- TweenManager, creating tweens, tween config, easing functions, tween chains, stagger, yoyo, repeat, callbacks, and tween targets.

Key source paths: src/tweens/TweenManager.js, src/tweens/tween/Tween.js, src/tweens/tween/TweenChain.js, src/tweens/tween/BaseTween.js, src/tweens/builders/, src/tweens/typedefs/, src/tweens/events/, src/math/easing/ Related skills: ../sprites-and-images/SKILL.md, ../animations/SKILL.md

Quick Start

// In a Scene's create() method:

const logo = this.add.image(100, 300, 'logo');

// Basic tween -- move the logo to x:600 over 2 seconds
this.tweens.add({
    targets: logo,
    x: 600,
    duration: 2000,
    ease: 'Power2'
});

this.tweens is the scene's TweenManager instance, available in every Scene. The add() method creates a tween, adds it to the manager, and starts playback immediately.

Core Concepts

Tween Lifecycle

Created -> Active (onActive) -> Start Delayed (delay) -> Playing (onStart, onUpdate per frame) -> Yoyo/Repeat (onYoyo, onRepeat) -> Loop (onLoop) -> Complete (onComplete, then auto-destroyed unless persist: true).

Fire-and-Forget Design

Tweens auto-destroy after completion. You do not need to store a reference unless you want to control them later. Set persist: true in the config to keep a tween alive after completion for replay via tween.play() or tween.restart(). You must manually call tween.destroy() on persisted tweens when done.

Targets

The targets property accepts a single object, an array of objects, or a function that returns either. Targets are typically Game Objects but can be any JavaScript object with numeric properties. A tween will not manipulate any property that begins with an underscore.

// Single target
this.tweens.add({ targets: sprite, alpha: 0, duration: 500 });

// Multiple targets
this.tweens.add({ targets: [sprite1, sprite2, sprite3], y: 100, duration: 1000 });

Property Values

this.tweens.add({
    targets: sprite,
    x: 400,                  // absolute value
    y: '-=100',              // relative (subtract 100 from current)
    rotation: '+=3.14',      // relative (add to current)
    alpha: { value: 0, duration: 300, ease: 'Cubic.easeIn' },  // per-property config
    scale: [0.5, 1.5, 1],   // array: interpolates through values over duration
    angle: function (target, key, value, targetIndex, totalTargets, tween) {
        return targetIndex * 90;   // function: called once per target
    },
    duration: 1000
});

Array values use linear interpolation by default; override with the interpolation config ('linear', 'bezier', 'catmull').

Common Patterns

Basic Tween

this.tweens.add({
    targets: this.player,
    x: 500,
    y: 300,
    duration: 1000,
    ease: 'Sine.easeInOut'
});

Multiple Properties with Per-Property Config

this.tweens.add({
    targets: this.enemy,
    x: { value: 600, duration: 1500, ease: 'Bounce.easeOut' },
    y: { value: 200, duration: 1000, ease: 'Power2' },
    alpha: { value: 0.5, duration: 500, delay: 1000 }
});

Yoyo and Repeat

this.tweens.add({
    targets: this.coin,
    y: '-=50',
    duration: 600,
    ease: 'Sine.easeInOut',
    yoyo: true,         // returns to start value after reaching end
    hold: 200,          // pause 200ms at the end value before yoyo-ing back
    repeat: -1,         // -1 = infinite, 0 = play once, 1 = play twice, etc.
    repeatDelay: 300     // pause 300ms before each repeat
});

repeat controls how many extra times each property plays. A repeat of 1 means the tween plays twice total. The loop property (on BaseTween) restarts the entire tween from scratch, including all properties. Use repeat for property-level looping and loop for tween-level looping.

Stagger

Stagger offsets a value across multiple targets via this.tweens.stagger():

// 100ms delay between each target
delay: this.tweens.stagger(100)

// From center outward
delay: this.tweens.stagger(200, { from: 'center' })

// Range: distribute 0-1000ms across targets
delay: this.tweens.stagger([0, 1000])

// Grid stagger with easing
delay: this.tweens.stagger(500, { grid: [10, 6], from: 'center', ease: 'Cubic.easeOut' })

StaggerConfig: start (offset), ease (string/function), from ('first'/'center'/'last'/index), grid ([w, h]).

Tween Chain

A TweenChain plays tweens in sequence. Each tween in the chain starts after the previous one completes:

this.tweens.chain({
    targets: this.player,
    tweens: [
        { x: 300, duration: 1000, ease: 'Power2' },
        { y: 500, duration: 800, ease: 'Bounce.easeOut' },
        { scale: 2, duration: 500 },
        { alpha: 0, duration: 400 }
    ],
    loop: 1,          // loop the entire chain once (plays twice total)
    loopDelay: 500,
    onComplete: function () {
        console.log('Chain finished');
    }
});

Each entry in tweens is a standard TweenBuilderConfig. Chain-level config supports loop, loopDelay, completeDelay, paused, persist, and chain-level callbacks. Per-tween callbacks (onUpdate, onRepeat, onYoyo) belong on individual entries. Use chain.add(tweenConfigs) to append dynamically.

Relative Values

this.tweens.add({
    targets: sprite,
    x: '+=200',    // add 200 to current x
    y: '-=50',     // subtract 50 from current y
    angle: '+=180',
    duration: 1000
});

Callbacks and Events

this.tweens.add({
    targets: sprite,
    x: 600,
    duration: 2000,

    // All callbacks receive (tween, targets, ...params)
    onStart: function (tween, targets) { },
    onUpdate: function (tween, targets) { },     // per-property, per-target, per-frame
    onYoyo: function (tween, targets) { },
    onRepeat: function (tween, targets) { },
    onLoop: function (tween, targets) { },
    onComplete: function (tween, targets) { },

    onCompleteParams: ['extra', 'args'],
    callbackScope: this
});

// Set callback after creation
tween.setCallback('onComplete', function (tween, targets) { }, []);

// Event emitter style (tweens extend EventEmitter)
tween.on('complete', function (tween, targets) { });

Number Tweens

A Number Tween has no target object. It tweens between two numeric values:

const counter = this.tweens.addCounter({
    from: 0,
    to: 100,
    duration: 2000,
    ease: 'Linear',
    onUpdate: function (tween) {
        const value = tween.getValue();
        console.log(value);   // 0 ... 100
    }
});

Controlling and Killing Tweens

const tween = this.tweens.add({ targets: sprite, x: 600, duration: 2000, persist: true });

// Playback control
tween.pause();                  tween.resume();
tween.stop();                   // flags for removal; fires onStop
tween.restart();                // reset and replay from beginning
tween.seek(1000);               // seek to 1000ms (suppresses events by default)
tween.complete();               // immediately complete; fires onComplete
tween.completeAfterLoop(0);     // finish after current loop
tween.forward(500);             tween.rewind(500);
tween.setTimeScale(0.5);       // per-tween speed
tween.updateTo('x', 800);      // change end value mid-tween

// Manager-level control
this.tweens.killAll();                     // destroy all tweens
this.tweens.killTweensOf(sprite);          // destroy tweens on target
this.tweens.isTweening(sprite);            // boolean check
this.tweens.pauseAll();                    this.tweens.resumeAll();
this.tweens.setGlobalTimeScale(0.5);       // global speed

Configuration Reference

TweenBuilderConfig

TweenChainBuilderConfig

NumberTweenBuilderConfig

TweenPropConfig (Per-Property Object)

Used when a property value is an object instead of a number/string. Supports: value, getActive, getEnd, getStart, ease, delay, duration, yoyo, hold, repeat, repeatDelay, flipX, flipY, interpolation. All override the tween-level defaults for that one property.

Easing Functions

All easing names are case-insensitive. Use the string name in the ease config property.

Power Aliases

Full Easing List

Each type supports .easeIn, .easeOut, .easeInOut variants. The bare name defaults to Out.

Types: Quad, Cubic, Quart, Quint, Sine, Expo, Circ, Elastic, Back, Bounce.

Usage: 'Sine.easeInOut', 'Bounce.easeIn', 'Cubic.easeOut', 'Back' (same as 'Back.easeOut').

Special: Linear (no easing), Stepped (discrete steps -- easeParams: [numSteps]).

Custom: ease: function (t) { return t * t; } where t is 0 to 1.

Events

Tweens (and TweenChains) extend EventEmitter. You can listen via .on():

Event listener signature for Tween events: function(tween, targets). During seeking (tween.isSeeking === true), events and callbacks are suppressed by default.

API Quick Reference

TweenManager (this.tweens)

Tween Instance

Key properties: targets, duration, elapsed, progress (0-1), totalProgress (0-1 including loops), totalDuration, timeScale, paused, persist, data (TweenData[]), isInfinite, isNumberTween.

TweenChain Instance

Extends BaseTween. Has all tween playback methods (play, pause, resume, stop, restart, complete, etc.) plus add(tweenConfigs) to append tweens dynamically. Properties: currentTween, currentIndex.

Gotchas

• Underscore properties are ignored. A tween will skip any property whose name starts with _.
• Tweens auto-destroy. If you store a reference to a tween and try to use it after completion, it may be destroyed. Set persist: true to keep it alive, but you must destroy() it yourself when done.
• repeat vs loop. repeat is per-property (on TweenData). loop restarts the entire tween. A repeat of 1 means the property plays twice total.
• loop: -1 means onComplete never fires. An infinitely looping tween never completes. Use completeAfterLoop() to end it gracefully.
• Seeking suppresses events. When calling tween.seek(), events and callbacks are not dispatched unless you pass true as the third argument.
• Stagger only works with multiple targets. Using this.tweens.stagger() on a single-target tween has no visible stagger effect.
• Destroyed targets. A tween completes early if its target has isDestroyed set to true. Always clean up tweens before destroying the objects they reference, or rely on this auto-check.
• TweenManager.timeScale multiplies with Tween.timeScale. The effective speed is managerTimeScale * tweenTimeScale. Setting either to 0 freezes the tween.
• Duration cannot be zero. Internally clamped to a minimum of 0.01ms.
• TweenChain targets are inherited. If you set targets at the chain level, individual tweens in the chain inherit them unless they specify their own.

Source File Map