godot-visual-effects/scripts/MultiParticles.cs

using Godot;
using System;

namespace GodotVisualEffects
{
    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;
            }
        }
    }
}