godot-visual-effects/scripts/MultiParticles.cs

using System;
using Godot;

/**
 * MultiParticles : Node3D
 *
 * This class turns possible to control multiple particles in sync.
 * Inspired by https://www.reddit.com/r/godot/comments/181ui9c/comment/kaewcca/?context=3
 */
public partial class MultiParticles : Node3D
{
    [Export]
    public bool Emitting = true;

    [Export]
    public bool OneShot = false;

    [Export]
    public Godot.Collections.Array<GpuParticles3D> Particles;

    double Lifetime = 0.0f;

    public override void _Ready()
    {
        if (Emitting)
        {
            StartEmitters();
        }
    }

    void GetLifetime()
    {
        foreach (var particle in Particles)
        {
            if (particle.Lifetime > Lifetime)
            {
                Lifetime = particle.Lifetime;
            }
        }
    }

    public async void StartEmitters()
    {
        GetLifetime();

        foreach (var particle in Particles)
            particle.Emitting = true;

        await ToSignal(GetTree().CreateTimer(Lifetime), SceneTreeTimer.SignalName.Timeout);
        DisposeOfEmitters();

        if (!OneShot)
        {
            StartEmitters();
        }
    }

    void DisposeOfEmitters()
    {
        foreach (var particle in Particles)
        {
            particle.Emitting = false;
        }
    }
}