/actions-and-utilities

name: actions-and-utilities
description: "Use this skill when working with Phaser 4 utility functions, actions, alignment, grid layout, or batch operations on game objects. Triggers on: align, grid layout, actions, set operations on groups of game objects."

Phaser 4 -- Actions & Utility Functions

> Phaser.Actions namespace for batch operations on Game Object arrays, plus Phaser.Utils.Array, Phaser.Utils.Objects, and Phaser.Utils.String helper functions.

**Related skills:** ../groups-and-containers/SKILL.md, ../sprites-and-images/SKILL.md

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Quick Start

// Create 20 sprites and batch-position them in a grid
const sprites = [];
for (let i = 0; i < 20; i++) {
    sprites.push(this.add.sprite(0, 0, 'gem'));
}

// Arrange into a 5x4 grid
Phaser.Actions.GridAlign(sprites, {
    width: 5,
    height: 4,
    cellWidth: 64,
    cellHeight: 64,
    x: 100,
    y: 100
});

// Fade alpha from 0 to 1 across all sprites
Phaser.Actions.Spread(sprites, 'alpha', 0, 1);

// Offset each sprite's x by 10, with a step of 2 per item
Phaser.Actions.IncX(sprites, 10, 2);

// Works with Groups too
const group = this.add.group({ key: 'star', repeat: 11 });
Phaser.Actions.PlaceOnCircle(group.getChildren(), new Phaser.Geom.Circle(400, 300, 200));

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Core Concepts

The Actions Pattern

Every Action in `Phaser.Actions` follows the same pattern:

1. **First argument is always an array** of Game Objects (or any objects with the required public properties like `x`, `y`, `alpha`, etc.). 2. **Returns the same array**, enabling chaining or pass-through. 3. **Works with Groups** by passing `group.getChildren()`. 4. Actions do NOT store state. They are one-shot batch operations.

PropertyValueSet and PropertyValueInc

Most Set/Inc actions delegate to two core functions:

• **`PropertyValueSet(items, key, value, step, index, direction)`** -- Sets `items[i][key] = value + (i * step)`.
• **`PropertyValueInc(items, key, value, step, index, direction)`** -- Adds `items[i][key] += value + (i * step)`.

The `step` parameter adds an incremental offset per item. The `index` and `direction` parameters control iteration start point and order (1 = forward, -1 = backward).

Geometry-Based Placement

Actions like `PlaceOnCircle`, `PlaceOnLine`, `RandomRectangle`, etc. accept Phaser geometry objects (`Phaser.Geom.Circle`, `Phaser.Geom.Line`, etc.), NOT Game Object shapes. If using a `Phaser.GameObjects.Circle`, pass its `.geom` property instead.

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All Actions

Property Setters

| Action | Signature | Description | |---|---|---| | `SetX` | `(items, value, step?, index?, direction?)` | Set `x` property | | `SetY` | `(items, value, step?, index?, direction?)` | Set `y` property | | `SetXY` | `(items, x, y?, stepX?, stepY?, index?, direction?)` | Set both `x` and `y`; `y` defaults to `x` | | `SetAlpha` | `(items, value, step?, index?, direction?)` | Set `alpha` | | `SetBlendMode` | `(items, value, index?, direction?)` | Set blend mode | | `SetDepth` | `(items, value, step?, index?, direction?)` | Set render depth | | `SetHitArea` | `(items, hitArea?, callback?)` | Set interactive hit area | | `SetOrigin` | `(items, originX, originY?, stepX?, stepY?, index?, direction?)` | Set origin point | | `SetRotation` | `(items, value, step?, index?, direction?)` | Set rotation (radians) | | `SetScale` | `(items, scaleX, scaleY?, stepX?, stepY?, index?, direction?)` | Set both scale axes | | `SetScaleX` | `(items, value, step?, index?, direction?)` | Set `scaleX` | | `SetScaleY` | `(items, value, step?, index?, direction?)` | Set `scaleY` | | `SetScrollFactor` | `(items, x, y?, stepX?, stepY?, index?, direction?)` | Set scroll factor | | `SetScrollFactorX` | `(items, value, step?, index?, direction?)` | Set horizontal scroll factor | | `SetScrollFactorY` | `(items, value, step?, index?, direction?)` | Set vertical scroll factor | | `SetTint` | `(items, topLeft, topRight?, bottomLeft?, bottomRight?)` | Set tint color(s) | | `SetVisible` | `(items, value, index?, direction?)` | Set visibility | | `PropertyValueSet` | `(items, key, value, step?, index?, direction?)` | Generic: set any named property |

Property Incrementers

| Action | Signature | Description | |---|---|---| | `IncX` | `(items, value, step?, index?, direction?)` | Add to `x` | | `IncXY` | `(items, x, y?, stepX?, stepY?, index?, direction?)` | Add to `x` and `y` | | `IncY` | `(items, value, step?, index?, direction?)` | Add to `y` | | `IncAlpha` | `(items, value, step?, index?, direction?)` | Add to `alpha` | | `Angle` | `(items, value, step?, index?, direction?)` | Add to `angle` (degrees) | | `Rotate` | `(items, value, step?, index?, direction?)` | Add to `rotation` (radians) | | `ScaleX` | `(items, value, step?, index?, direction?)` | Add to `scaleX` | | `ScaleXY` | `(items, scaleX, scaleY?, stepX?, stepY?, index?, direction?)` | Add to both scale axes | | `ScaleY` | `(items, value, step?, index?, direction?)` | Add to `scaleY` | | `PropertyValueInc` | `(items, key, value, step?, index?, direction?)` | Generic: increment any named property |

Placement on Geometry

| Action | Signature | Description | |---|---|---| | `PlaceOnCircle` | `(items, circle, startAngle?, endAngle?)` | Evenly space on circle perimeter | | `PlaceOnEllipse` | `(items, ellipse, startAngle?, endAngle?)` | Evenly space on ellipse perimeter | | `PlaceOnLine` | `(items, line)` | Evenly space along a line | | `PlaceOnRectangle` | `(items, rect, shift?)` | Evenly space on rectangle perimeter | | `PlaceOnTriangle` | `(items, triangle, stepRate?)` | Evenly space on triangle perimeter | | `RandomCircle` | `(items, circle)` | Random positions within a circle | | `RandomEllipse` | `(items, ellipse)` | Random positions within an ellipse | | `RandomLine` | `(items, line)` | Random positions along a line | | `RandomRectangle` | `(items, rect)` | Random positions within a rectangle | | `RandomTriangle` | `(items, triangle)` | Random positions within a triangle |

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