ParticleEmitter

Pooled 2D particles.

import { ParticleEmitter, EmitterConfig, Range } from "willow";

ParticleEmitter

class ParticleEmitter extends Node

Extends Node.

Particle emitter node managing a pool of simulated 2D particles.

ParticleEmitter: constructors

new ParticleEmitter(name?: string, config?: EmitterConfig)

Constructs a new particle emitter node with optional name and config.

ParticleEmitter: properties

Member	Description
config: EmitterConfig	Emitter configuration controlling particle spawning and physics.
readonly particleCount: int	Current number of active particles alive in the simulation.
readonly aliveCount: int	Alias for particleCount. Current number of active alive particles.
readonly active: boolean	Whether the emitter is currently active and spawning particles.
seed: int	Deterministic RNG seed state for particle variations.

ParticleEmitter: methods

Member	Description
start(): void	Begins emitting particles according to the emitter config rate.
stop(): void	Stops emitting new particles; live particles continue until death.
reset(): void	Stops emission and immediately clears all active particles.
burst(count: int): void	Spawns a burst of particles immediately.
update(dt: float): void	Advances particle simulation and quad rendering by dt seconds.
setSeed(seed: int): void	Sets the random seed for reproducible particle variation.
bounds(): Rect	Axis-aligned bounding box covering all currently alive particles.

ParticleEmitter: static methods

Member	Description
static create(name: string, config: EmitterConfig): ParticleEmitter	Factory creating a new particle emitter node.

EmitterConfig

class EmitterConfig

Configuration options for particle emitter simulation and visuals.

EmitterConfig: constructors

new EmitterConfig()

Constructs an EmitterConfig with default settings.

EmitterConfig: properties

Member	Description
maxParticles: int	Maximum pool size of concurrent particles. Defaults to 128.
emitRate: float	Emission rate in particles spawned per second. Defaults to 10.0.
lifetime: Range	Lifetime range of spawned particles in seconds.
lifetimeMin: float	Minimum particle lifetime in seconds. Defaults to 1.0.
lifetimeMax: float	Maximum particle lifetime in seconds. Defaults to 1.0.
speed: Range	Initial particle speed range in pixels per second.
speedMin: float	Minimum initial speed in pixels per second. Defaults to 50.0.
speedMax: float	Maximum initial speed in pixels per second. Defaults to 50.0.
angle: Range	Emission angle range in radians. Defaults to full circle [0, 2*PI].
angleMin: float	Minimum emission angle in radians. Defaults to 0.0.
angleMax: float	Maximum emission angle in radians. Defaults to 2*PI.
gravityX: float	Constant horizontal acceleration applied to particles. Defaults to 0.0.
gravityY: float	Constant vertical acceleration applied to particles. Defaults to 0.0.
startScale: float	Scale factor at particle birth. Defaults to 1.0.
endScale: float	Scale factor at particle death. Defaults to 1.0.
scaleStart: float	Alias for startScale. Scale factor at particle birth. Defaults to 1.0.
scaleEnd: float	Alias for endScale. Scale factor at particle death. Defaults to 1.0.
startAlpha: float	Alpha multiplier at particle birth. Defaults to 1.0.
endAlpha: float	Alpha multiplier at particle death. Defaults to 0.0.
alphaStart: float	Alias for startAlpha. Alpha multiplier at particle birth. Defaults to 1.0.
alphaEnd: float	Alias for endAlpha. Alpha multiplier at particle death. Defaults to 0.0.
startColor: Color	Tint color at particle birth. Defaults to white.
endColor: Color	Tint color at particle death. Defaults to white.
colorStart: Color	Alias for startColor. Tint color at particle birth.
colorEnd: Color	Alias for endColor. Tint color at particle death.
blendMode: string	Compositor blend mode for particles. Defaults to "add".
worldSpace: boolean	When true, emitted particles remain in world space rather than following node. Defaults to false.

Range

class Range

A min/max range of numbers. EmitterConfig uses it for lifetime, speed and angle.

Range: constructors

new Range(min: float, max: float)

Range: properties

Member	Description
min: float	Lower bound, inclusive.
max: float	Upper bound, inclusive.

Range: methods

Member	Description
random(): float	A uniformly-distributed random value in [min, max]. Returns min when min === max.