Particle parameter reference
Every knob in a particle preset, grouped the way the preset editor groups them, plus the recipes that show how the groups combine.
New to particles? Start with the particles overview for presets, burst vs. loop, and the live preview. This page is the full parameter map. Distances are in meters and times in seconds. Every parameter with a variation partner adds per-particle randomness: each particle draws its value from a range centered on the base value, so variation is what turns a uniform stream into something organic.
Note. All angle-type fields (spread angle, radial amount, particle angle, angular speed) display in degrees in the preset editor.
Emission
Where particles are born, how many, how fast, and in which direction.
| Parameter | Range | What it does |
|---|---|---|
| Birth rate (+ variation) | 0–3000 /s | Particles emitted per second while the emitter runs. The single biggest density control. |
| Lifetime (+ variation) | 0–10 s | How long each particle lives. Variation staggers deaths so a stream doesn't vanish in pulses. |
| Speed (+ variation) | 0–1.5 | Initial launch speed. Zero makes particles that hang where they're born and move only under forces. |
| Spread angle | 0–360° | Cone of randomness around each particle's birth direction. 0° is a laser-straight stream; wide values scatter. |
| Shape | point · sphere · box · plane · cone · cylinder · torus | The geometric region particles are born from. |
| Shape size | 0–10 m per axis | Dimensions of the emitter shape. A 3 × 0.01 × 3 plane is a snowfall ceiling; a 0.05 sphere is a candle flame's core. |
| Birth location | surface · volume · vertices | Whether particles start on the shape's skin, anywhere inside it, or at a regular grid of points on it. |
| Birth direction | normal · world · local | Normal launches outward from the shape's surface; world and local use the emission direction vector, in world space or the emitter's own space respectively. |
| Emission direction | vector | The direction used by world/local birth direction. (0, 1, 0) is straight up. |
| Radial amount | 0–360° | How much of the shape's circumference emits. Full circle sprays all around; a slice makes a directional fan. |
| Torus inner radius | 0–1 | Thickness of the torus ring, as a fraction. Only the torus shape uses it. |
| Burst count | 0–1000 | Particles released in one burst when a one-shot emitter fires (see burst vs. loop). |
| Particles inherit transform | on / off | On: existing particles ride along when the emitter moves (a torch carried through the room). Off: born particles stay in the world where they were emitted (a smoke trail behind a moving object). |
Physics
What happens to particles after birth.
| Parameter | Range | What it does |
|---|---|---|
| Mass (+ variation) | 0–10 | Heavier particles respond less to forces. Mass variation makes a mixed flurry where some flakes dart and some drift. |
| Angle (+ variation) | 0–360° | Initial spin orientation of each particle's sprite. |
| Angular speed (+ variation) | −/+ | How fast each sprite rotates over its life; negative reverses direction. Pair with variation so sprites don't spin in lockstep. |
| Damping | 0–1 | Drag. Higher values bleed off velocity so particles launch fast and coast to a stop, the heart of any explosion that blooms and hangs. |
| Stretch | 0–10 | Elongates sprites along their motion, turning dots into streaks for rain, sparks, or warp lines. |
| Acceleration | vector, −10–10 per axis | A constant force on every particle. (0, −9.8, 0) is Earth gravity; a small −Y is lazy snow; +Y makes embers rise. |
Color
Particle opacity is part of color: the alpha of each color you pick is the particle's opacity, and it layers with the opacity curve below.
| Parameter | Options | What it does |
|---|---|---|
| Color mode | constant · random · evolving | Constant: every particle is the first color. Random: each particle picks a blend between the two colors at birth and keeps it. Evolving: each particle shifts from the first color to the second over its lifetime. |
| Color | color + alpha | The primary color. Its alpha sets base particle opacity. |
| Second color | color + alpha | The partner color for random and evolving modes. |
| Evolution power | 0–5 | Bends the evolving transition's timing. 1 is even; higher values hold the first color longer before a late shift. |
Tip. Evolving color is the fire trick: bright yellow-white evolving to deep red with a fading alpha reads as cooling embers with a single emitter.
Visual
How each particle draws.
| Parameter | Options / range | What it does |
|---|---|---|
| Size (+ variation) | 0–1 m | Sprite size at birth. |
| End size | 0–2×, + curve power 0–5 | Size at end of life, relative to birth size: shrink to 0 for dissolving sparks, or grow past 1 for billowing smoke. The power bends how quickly the change happens. |
| Opacity curve | constant · fade in · fade out · fade in/out · linear fade in · linear fade out | How opacity changes over each particle's life, multiplied with the color alpha. Fade in/out removes pops at both birth and death. |
| Billboard mode | billboard · Y-aligned · free rotating · velocity aligned | Billboard always faces the viewer; Y-aligned faces the viewer but stays upright; free rotating tumbles in 3D; velocity aligned points along the particle's motion (use with stretch for streaks). |
| Lighting | on / off | Whether scene lighting shades particles. Off for self-luminous effects (sparks, magic); on for matter (dust, snow) that should sit in the room's light. |
| Sort order | unsorted · depth near→far · depth far→near · age young→old · age old→young | Draw order within the effect. Unsorted is cheapest and fine for additive effects; depth sorting fixes layering artifacts with alpha-blended sprites. |
| Blend mode | additive · alpha · replace · multiply · screen | Additive brightens whatever is behind it; it's the default, and ideal for light-like effects. Alpha is ordinary transparency for solid matter. Multiply darkens (smoke, shadow); screen is a softer brighten; replace overwrites outright. |
| Sprite image | soft glow (default) · SF Symbol name | The picture each particle draws. The default is a soft radial glow; or type any SF Symbol name (snowflake, star.fill, heart.fill, sparkle) for shaped particles. |
Force fields
Three fields act on particles for their entire flight. All default to zero, which means off.
| Field | Parameters | What it does |
|---|---|---|
| Noise | strength 0–10 · scale 0–10 | Turbulence, a swirling and ever-shifting wind. Strength sets how hard particles are pushed; scale sets the size of the eddies (low = broad slow currents, high = fine jitter). This is the one parameter that makes snow and smoke stop looking synthetic. |
| Attraction | strength −10–10 · center point | Pulls every particle toward a point; negative strength pushes away. Orbit-like gathers, genie-into-the-lamp effects, or a repulsor that keeps a zone clear. |
| Vortex | strength 0–10 · axis | Swirls particles around an axis. A vertical axis with moderate strength is a dust devil; combine with upward acceleration for a rising tornado of sparks. |
Spawn
A preset may carry one secondary emitter: a complete child particle system that fires from the parent's particles rather than from the emitter shape. The child has its own full set of emission, physics, color, visual, and force-field parameters.
| Parameter | Options | What it does |
|---|---|---|
| Spawn occasion | on birth · on death · on update | When each parent particle triggers the child: at its birth, at its death (the fireworks pattern, where the shell dies and the crackle blooms), or continuously along its flight (trails). |
| Spread factor | 0–1 | How widely child particles scatter from their spawn point. |
| Velocity factor | 0–1 | How much of the parent particle's velocity the children inherit. At 0 they bloom in place; at 1 they carry the parent's momentum. |
| Inherit parent color | on / off | Children take their parent's current color, keeping a layered effect reading as one. |
| Child sprite | soft glow · SF Symbol name | The child system's own sprite image. |
Recipes
Snow. Looping emitter, wide flat plane overhead, volume birth, low
birth rate, long lifetime with variation, near-zero speed, gentle downward acceleration,
generous mass variation, a touch of noise at low scale, snowflake sprite,
alpha blend, lighting on, fade in/out opacity.
Embers. Looping emitter, small sphere, modest birth rate, slight upward acceleration, noise for wander, evolving color from hot yellow-orange to dark red with falling alpha, small size shrinking to 0, additive blend, default glow sprite, lighting off.
Magic sparkle. Attach to a moving entity, particles inherit transform off
so the trail hangs in space, short lifetimes, sparkle sprite, additive blend,
random color between two jewel tones, angular speed with variation, size shrinking to 0,
fade-out opacity curve.
Fireworks. One-shot (burst) emitter revealed on cue: high burst count from a point, high speed, full spherical spread, strong damping so the shell blooms and hangs, gravity pulling down, stretch for streaks, evolving color. Add a secondary emitter spawning on death with tiny, short-lived, white additive children — that's the crackle. Time it with a reveal or the Add Particle action in the actions reference.