Particle Systems

Description

This skill covers GPUParticles2D/3D and CPUParticles2D/3D in Godot 4 for visual effects like fire, smoke, explosions, trails, and ambient particles. GPU particles offer high performance for large counts; CPU particles provide deterministic results.

When To Use

• •Creating fire, smoke, sparks, explosions, dust clouds
• •Adding ambient effects (rain, snow, fireflies, fog)
• •Building projectile trails and impact effects
• •Using sub-emitters for multi-stage particle effects
• •Optimising particle systems for target platform

Prerequisites

• •Godot 4.3+ rendering basics
• •Understanding of materials and textures
• •Scene Architecture skill for organising VFX nodes

Instructions

1. GPUParticles2D Basics

1. •Add a GPUParticles2D node to your scene.
2. •Create a new ParticleProcessMaterial in the Process Material property.
3. •Assign a texture in the Texture property (or use the default point).
4. •Configure in the Inspector: Amount, Lifetime, Speed, Gravity, Emission Shape.

# Spawning a one-shot particle effect from code
func spawn_hit_effect(position: Vector2) -> void:
    var particles := preload("res://effects/hit_particles.tscn").instantiate()
    particles.global_position = position
    particles.emitting = true
    particles.one_shot = true
    particles.finished.connect(particles.queue_free)
    get_tree().current_scene.add_child(particles)

2. ParticleProcessMaterial Properties

Key properties to tune for common effects:

3. Common Effect Recipes

Fire

Amount: 50
Lifetime: 0.8
Direction: (0, -1, 0)
Spread: 15°
Initial Velocity: 40-80
Gravity: (0, -20, 0)  # negative = upward for 2D
Scale Curve: 1.0 → 0.0
Color Ramp: White → Yellow → Orange → Red → Transparent

Explosion (One-Shot)

Amount: 80
One Shot: true
Explosiveness: 1.0
Lifetime: 0.5
Emission Shape: Sphere (radius 5)
Direction: outward
Initial Velocity: 100-300
Damping: 50-80
Scale Curve: 1.0 → 0.3
Color Ramp: White → Yellow → Transparent

Trail

Amount: 30
Lifetime: 0.4
Emission Shape: Point
Initial Velocity: 0
Gravity: (0, 0, 0)
Scale Curve: 1.0 → 0.0
Use as Trail: true (set Trail properties)

4. Sub-Emitters (Godot 4+)

Sub-emitters let particles spawn child particles on birth, collision, or death.

1. •Create a second GPUParticles2D node.
2. •On the main particle's ParticleProcessMaterial, set Sub Emitter to the child node.
3. •Choose the trigger: at_end, at_collision, or constant.

Example: Firework that spawns sparks on death.

5. GPUParticles3D

Same workflow as 2D, but in 3D space:

1. •Add GPUParticles3D to the scene.
2. •Configure ParticleProcessMaterial (same properties, 3D vectors).
3. •Optionally assign a mesh in Draw Pass 1 for 3D-shaped particles.

# Trigger explosion and auto-cleanup
func explode_3d(pos: Vector3) -> void:
    var fx := preload("res://effects/explosion_3d.tscn").instantiate()
    fx.global_position = pos
    fx.emitting = true
    fx.one_shot = true
    fx.finished.connect(fx.queue_free)
    add_child(fx)

6. CPUParticles (Deterministic)

When you need deterministic particles (replays, networking) or target low-end hardware:

1. •Use CPUParticles2D or CPUParticles3D instead.
2. •Same properties as GPU variants but processed on CPU.
3. •Right-click a GPUParticles node → "Convert to CPUParticles" for quick conversion.

7. Particle Effect Manager

class_name EffectsManager
extends Node

const EFFECTS := {
    "hit": preload("res://effects/hit.tscn"),
    "explosion": preload("res://effects/explosion.tscn"),
    "dust": preload("res://effects/dust.tscn"),
}

func spawn(effect_name: String, pos: Vector2) -> void:
    var scene: PackedScene = EFFECTS.get(effect_name)
    if scene == null:
        push_warning("Unknown effect: %s" % effect_name)
        return
    
    var fx := scene.instantiate() as GPUParticles2D
    fx.global_position = pos
    fx.emitting = true
    fx.one_shot = true
    fx.finished.connect(fx.queue_free)
    get_tree().current_scene.add_child(fx)

Best Practices

• •Use one_shot = true and connect finished to queue_free() for transient effects.
• •Create an effects manager autoload to centralize spawning.
• •Preload particle scenes — don't load them on demand during gameplay.
• •Keep particle counts low on mobile; prefer CPUParticles on low-end devices.
• •Use explosiveness = 1.0 for one-shot bursts; use 0.0 for continuous emission.
• •Use visibility_rect (2D) or visibility_aabb (3D) to ensure particles aren't culled prematurely.

Common Pitfalls

• •Particles disappear at edges. The visibility_rect/visibility_aabb is too small. Increase it to cover the full effect area.
• •One-shot doesn't emit. You must call restart() or set emitting = true after adding to the tree.
• •Too many particles. Each GPU particle system has overhead. Pool or limit concurrent effects.
• •Not using object pooling. Instantiating and freeing particle scenes every frame is expensive. Pool them.

Reference

• •GPUParticles2D
• •GPUParticles3D
• •ParticleProcessMaterial