Particles

jEngine has two particle systems: CPU emitters (particle_emitter), which can collide and spawn sub-emitters, and GPU particles (gpu_particles) for clouds of hundreds of thousands. Both are simulated by one shared step, so they behave the same in every runtime.

Presets

The editor provides presets: Fire, Smoke, Explosion, Sparkle, Rain, Snow.

ParticleEmitter Properties

Property	Description
emission_rate	Particles per second
max_particles	Maximum alive particles
lifetime	Particle lifetime range (seconds)
speed	Initial speed range
angle	Emission angle range
color_start / color_end	Color gradient over lifetime
size_start / size_end	Size gradient over lifetime
gravity_modifier	Scales gravity on the particles
angular_velocity	Spin speed
burst_count	Particles per burst
active	Enable/disable emission
world_space	Emit in world or local space
emit_shape	Point, circle, box, …
blend_mode	Alpha, additive, …
color_curve / size_curve	Colour and size over lifetime, as curves
stretch	Stretch along the velocity
drag	Slows each particle by e^(-drag t), frame-rate independent
turbulence	strength, scale, speed: swirls along the curl of world-anchored noise
collision	Hit every non-sensor collider - kill or bounce
sub_emitters	Burst another emitter, found by entity name, where a particle dies or hits

An emitter can name a shared definition instead of carrying every field:

"particle_emitter": { "particle_source": "particles/fire.particle", "z_order": 10 }

GPU particles

gpu_particles is a stateless cloud: each particle is a closed form of its index and the time, evaluated on the GPU, so the CPU cost is one uniform and one draw per emitter whatever the count. It sorts with sprites by z_order like everything else. Use it for snow, dust, star fields and spell storms; use particle_emitter when particles must collide or trigger sub-emitters.

Scripting API

-- Emit a burst of particles
Particles.emit_burst(entity, 20)

-- Enable/disable continuous emission
Particles.set_active(entity, true)
Particles.set_active(entity, false)

-- Change emission rate
Particles.set_rate(entity, 50)

-- Any emitter field, by name
Particles.set(entity, "drag", 1.5)

-- Get total alive particle count
local count = Particles.get_count()