1681-engine / index / ParticleSim

Class: ParticleSim

Defined in: src/particles/ParticleSim.ts:10

The particles of one emitter as flat typed arrays (structure of arrays): position, velocity, age and lifetime, rotation and spin, and a per-particle random draw the curves can use. Pure, no Pixi: the emitter draws what this holds, and tests step it under node.

Live particles are packed at indices 0 … count - 1. A particle that dies is replaced by the last live one, so a step never leaves holes and never allocates; the order of particles is therefore not stable, which drawing does not need (every live index is written again each frame).

Constructors

Constructor

new ParticleSim(capacity): ParticleSim;

Defined in: src/particles/ParticleSim.ts:23

Parameters

Parameter	Type
capacity	number

Returns

ParticleSim

Properties

age

readonly age: Float32Array;

Defined in: src/particles/ParticleSim.ts:15

---

capacity

readonly capacity: number;

Defined in: src/particles/ParticleSim.ts:23

---

count

count: number = 0;

Defined in: src/particles/ParticleSim.ts:21

---

life

readonly life: Float32Array;

Defined in: src/particles/ParticleSim.ts:16

---

rot

readonly rot: Float32Array;

Defined in: src/particles/ParticleSim.ts:17

---

seed

readonly seed: Float32Array;

Defined in: src/particles/ParticleSim.ts:20

A random draw per particle (0–1), fixed for its life: size variance, flicker phase.

---

spin

readonly spin: Float32Array;

Defined in: src/particles/ParticleSim.ts:18

---

vx

readonly vx: Float32Array;

Defined in: src/particles/ParticleSim.ts:13

---

vy

readonly vy: Float32Array;

Defined in: src/particles/ParticleSim.ts:14

---

x

readonly x: Float32Array;

Defined in: src/particles/ParticleSim.ts:11

---

y

readonly y: Float32Array;

Defined in: src/particles/ParticleSim.ts:12

Methods

clear()

clear(): number;

Defined in: src/particles/ParticleSim.ts:86

Every particle gone; returns how many there were.

Returns

number

---

progress()

progress(i): number;

Defined in: src/particles/ParticleSim.ts:81

The share of its life particle i has lived (0–1).

Parameters

Parameter	Type
i	number

Returns

number

---

spawn()

spawn(
   x, 
   y, 
   vx, 
   vy, 
   life, 
   rot, 
   spin, 
   seed
): number;

Defined in: src/particles/ParticleSim.ts:36

Adds a particle; returns its index, or -1 when the sim is full. life is in seconds.

Parameters

Parameter	Type
x	number
y	number
vx	number
vy	number
life	number
rot	number
spin	number
seed	number

Returns

number

---

step()

step(
   dt, 
   gravityX, 
   gravityY, 
   drag
): number;

Defined in: src/particles/ParticleSim.ts:56

Advances every particle by dt seconds: gravity (px/s²) added to velocity, then drag, then position. Drag is the share of speed lost per second, applied as exp(-drag × dt) so it is the same at any frame rate. Returns how many particles died this step.

Parameters

Parameter	Type
dt	number
gravityX	number
gravityY	number
drag	number

Returns

number