SKILL.md
Full skill instructions
Godot 4.7 Baseline
- Expert patterns in this skill target Godot 4.7+ (stable, 2026-06-18).
- Consult the Godot 4.7 migration guide when upgrading projects from 4.6.
- NEVER assume 4.6 defaults (stretch mode, audio area_mask, RichTextLabel percent flags) without checking 4.7 migration notes.
Particle Systems
GPU-accelerated rendering, material-based configuration, and sub-emitters define performant VFX.
Available Scripts
vfx_shader_manager.gd
Expert custom shader integration for advanced particle VFX.
particle_burst_emitter.gd
One-shot particle bursts with auto-cleanup - essential for VFX systems.
custom_particle_logic.gdshader
Expert procedural particle movement logic. Demonstrates persistent CUSTOM data and USERDATA injection for dynamic wind/orbit effects.
sub_emitter_impact.gdshader
High-performance collision handling. Triggers sub-emitters (splashes/debris) using emit_subparticle() and COLLISION_NORMAL.
particle_attractor_opt.gd
Optimization pattern using cull_mask to isolate particle-attractor interactions, preventing global performance bottlenecks.
massive_swarm_multimesh.gd
Bypassing GPUParticles for millions of entities (fish, insects). Uses set_buffer_interpolated() for jitter-free high-count movement.
dynamic_userdata_modulation.gd
Clean architectual pattern for passing runtime variables to particle shaders via USERDATA to preserve GPU batching.
local_vs_global_coords.gd
Expert logic for switching between localized (Auras) and global (Trails) space. Includes correct restart() handling for teleports.
smart_oneshot_recycler.gd
Robust lifecycle management using the finished signal and restart() to avoid async emission failures.
screenspace_weather_heightfield.gd
Optimizing global weather (Rain/Snow) using Camera-snapped GPUParticlesCollisionHeightField3D.
particle_lod_manager.gd
Hierarchical LOD for environmental VFX. Uses visibility_range and margins to cull distant torches or fires completely.
2d_physics_interpolation_fix.gd
Expert workaround for 2D particle stuttering. Switches to CPUParticles2D with fract_delta for smooth physics-parented movement.
NEVER Do in Particle Systems
- NEVER use
amount_ratioto optimize performance dynamically — It does not save GPU memory or improve processing; the fullamountis still allocated. Change theamountproperty directly instead. - NEVER use CPUParticles2D for performance-critical effects on Desktop — Use GPUParticles unless targeting low-end mobile with no GPU support. However, use CPUParticles2D if you need Physics Interpolation for smooth trails on moving bodies in 2D.
- NEVER set
preprocessto extremely high values — High values (e.g., 60s) will force the GPU to simulate thousands of frames in a single render tick, potentially causing an immediate GPU crash. - NEVER leave
visibility_aabbunconfigured for large systems — Incorrect AABBs cause frustum culling errors (particles popping out) and break LOD calculations. Generate AABBs using the editor toolbar. - NEVER enable turbulence on Mobile/Web without testing — 3D noise evaluation per particle is extremely heavy. Disable via Feature Tags on lower-end platforms.
- NEVER forget to
queue_free()one-shot particles — Use thefinishedsignal instead of an arbitrary Timer for safe lifecycle management. - NEVER use
local_coords = truefor trails — Smoke or fire left behind by a projectile MUST use global space (local_coords = false) or the trail will follow the projectile like a stiff stick. - NEVER expect GPUParticles2D to interpolate correctly in Godot 4.3 — They stutter when parented to physics bodies. Use
CPUParticles2Dwithfract_delta = truefor high-speed 2D movement. - NEVER trigger
emitting = trueimmediately after afinishedsignal — Async GPU state delays can cause the restart to fail. Use therestart()method instead. - NEVER attempt recursion with sub-emitters — A particle system cannot be its own sub-emitter; it will silently fail.
- NEVER forget alpha in color gradients — Particles that disappear instantly at the end of their lifetime look harsh; always add a gradient point at 1.0 with 0.0 alpha for a smooth exit.
- NEVER use
EMISSION_SHAPE_POINTfor volumentric explosions — Spawning all particles at a single point looks flat. Use a Sphere or Box shape for natural 3D spread. - NEVER forget to set
emitting = falseinitially for one-shot VFX — This prevents unwanted emission at the scene origin before you've had a chance to position the node via script.
Basic Setup
# Add GPUParticles2D node
# Set Amount: 32
# Set Lifetime: 1.0
# Set One Shot: true (for explosions)
Particle Material
# Create ParticleProcessMaterial
var material := ParticleProcessMaterial.new()
# Emission shape
material.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_SPHERE
material.emission_sphere_radius = 10.0
# Gravity
material.gravity = Vector3(0, 98, 0)
# Velocity
material.initial_velocity_min = 50.0
material.initial_velocity_max = 100.0
# Color
material.color = Color.ORANGE_RED
# Apply to godot-particles
$GPUParticles2D.process_material = material
Common Effects
Explosion
extends GPUParticles2D
func _ready() -> void:
one_shot = true
amount = 64
lifetime = 0.8
explosiveness = 0.9
var mat := ParticleProcessMaterial.new()
mat.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_SPHERE
mat.emission_sphere_radius = 5.0
mat.initial_velocity_min = 100.0
mat.initial_velocity_max = 200.0
mat.gravity = Vector3(0, 200, 0)
mat.scale_min = 0.5
mat.scale_max = 1.5
process_material = mat
emitting = true
Smoke Trail
extends GPUParticles2D
func _ready() -> void:
amount = 16
lifetime = 2.0
var mat := ParticleProcessMaterial.new()
mat.direction = Vector3(0, -1, 0)
mat.initial_velocity_min = 20.0
mat.initial_velocity_max = 40.0
mat.scale_min = 0.5
mat.scale_max = 1.0
mat.color = Color(0.5, 0.5, 0.5, 0.5)
process_material = mat
Sparkles/Stars
var mat := ParticleProcessMaterial.new()
mat.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
mat.emission_box_extents = Vector3(100, 100, 0)
mat.gravity = Vector3.ZERO
mat.angular_velocity_min = -180
mat.angular_velocity_max = 180
mat.scale_min = 0.1
mat.scale_max = 0.5
# Use star texture
$GPUParticles2D.texture = load("res://textures/star.png")
$GPUParticles2D.process_material = mat
Spawn Particles on Demand
# player.gd
const EXPLOSION_EFFECT := preload("res://effects/explosion.tscn")
func die() -> void:
var explosion := EXPLOSION_EFFECT.instantiate()
get_parent().add_child(explosion)
explosion.global_position = global_position
explosion.emitting = true
queue_free()
3D Particles
extends GPUParticles3D
func _ready() -> void:
amount = 100
lifetime = 3.0
var mat := ParticleProcessMaterial.new()
mat.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
mat.emission_box_extents = Vector3(10, 0.1, 10)
mat.direction = Vector3.UP
mat.initial_velocity_min = 2.0
mat.initial_velocity_max = 5.0
mat.gravity = Vector3(0, -9.8, 0)
process_material = mat
Color Gradients
var mat := ParticleProcessMaterial.new()
# Create gradient
var gradient := Gradient.new()
gradient.add_point(0.0, Color.YELLOW)
gradient.add_point(0.5, Color.ORANGE)
gradient.add_point(1.0, Color(0.5, 0.0, 0.0, 0.0)) # Fade to transparent red
var gradient_texture := GradientTexture1D.new()
gradient_texture.gradient = gradient
mat.color_ramp = gradient_texture
Sub-Emitters
# Particles that spawn godot-particles (fireworks)
$ParentParticles.sub_emitter = $ChildParticles.get_path()
$ParentParticles.sub_emitter_mode = GPUParticles2D.SUB_EMITTER_AT_END
Best Practices
1. Use Texture for Shapes
# Add texture to godot-particles
$GPUParticles2D.texture = load("res://textures/particle.png")
2. Lifetime Management
# Auto-delete one-shot godot-particles
if one_shot:
await get_tree().create_timer(lifetime).timeout
queue_free()
3. Performance
# Reduce amount for mobile
if OS.get_name() == "Android":
amount = amount / 2
Expert Pattern: Particle-Audio-Syncer (Collision Sub-Emitters)
GPU particles do not emit CPU signals for individual collisions. To sync visual impacts, use the Sub-Emitter system to spawn secondary effects (sparks, dust) on contact.
func setup_collision_vfx(primary: GPUParticles3D, impact: GPUParticles3D) -> void:
# 1. Assign impact system as sub-emitter
primary.sub_emitter = primary.get_path_to(impact)
var mat := primary.process_material as ParticleProcessMaterial
if mat:
# 2. Enable collision and set trigger mode
mat.collision_mode = ParticleProcessMaterial.COLLISION_RIGID
mat.sub_emitter_mode = ParticleProcessMaterial.SUB_EMITTER_AT_COLLISION
mat.sub_emitter_amount_at_collision = 1 # Spawn 1 spark per impact
[!IMPORTANT] Since the CPU cannot track individual GPU collisions, sync audio by playing a randomized looping "impact" sound while the primary emitter is active, or use
CPUParticlesfor precise RayCast-driven audio timing.
Expert Pattern: Fluid-Simulation-Particles (Custom Shaders)
For high-performance liquid or swarm effects, bypass ParticleProcessMaterial and use a custom particles shader with state persistence.
shader_type particles;
// 'keep_data' allows the shader to remember state between frames
render_mode keep_data;
void start() {
if (RESTART) {
// Initialize position and custom fluid density
TRANSFORM[3].xyz = EMISSION_TRANSFORM[3].xyz;
CUSTOM.x = 1.0;
}
}
void process() {
// Apply gravity and attractor forces
VELOCITY += ATTRACTOR_FORCE * DELTA;
// Built-in GPU collision handling
if (COLLIDED) {
VELOCITY = reflect(VELOCITY, COLLISION_NORMAL) * 0.5;
TRANSFORM[3].xyz += COLLISION_NORMAL * COLLISION_DEPTH;
}
}
Expert Pattern: VFX-Pool-Manager
Prevent frame-spikes from frequent instantiate() and queue_free() calls by pooling and reusing one-shot particle systems.
class_name VFXPool extends Node
@export var vfx_scene: PackedScene
var pool: Array[GPUParticles3D] = []
func _ready() -> void:
for i in 20:
var inst := vfx_scene.instantiate() as GPUParticles3D
add_child(inst)
inst.emitting = false
inst.finished.connect(func(): pool.append(inst))
pool.append(inst)
func spawn(pos: Vector3) -> void:
if pool.is_empty(): return
var vfx = pool.pop_back()
vfx.global_position = pos
# Use restart() to avoid async GPU state delays
vfx.restart()
Reference
Related
- Master Skill: godot-master
