Guides VFX & Particles Particles Emission And Shapes

VFX & Particles Particles 5 min read Updated Aug 2026

Emission And Shapes

Emission decides when particles are created. Shape decides where they are created and which direction they initially move.

Most particle effects are recognizable from those two choices before color, texture, or rendering polish are added.

Rate over Time

Rate over Time emits particles every second while the system is playing.

Use it for continuous effects:

  • fire
  • smoke
  • rain
  • snow
  • torch embers
  • ambient motes
  • engine exhaust

Low rates create sparse, readable effects. High rates create dense effects but cost more to simulate and draw.

Rate over Distance

Rate over Distance emits as the emitter moves.

Use it for movement trails:

  • footsteps
  • tire dust
  • sword trails
  • projectile streaks
  • character dash effects

Distance emission keeps particle density consistent with movement. A fast object emits more particles because it travels farther; a stopped object emits none.

Bursts

A burst emits particles at a specific time in the emitter cycle. Each burst has a Time, Count, Cycles, Interval, and Probability.

Use bursts for one-shot events:

  • impact sparks
  • pickup flash
  • jump dust
  • explosion core
  • muzzle flash
  • damage hit feedback

A burst can be combined with looping emission. For example, a fire effect might burst when lit, then continue with a looping flame and smoke rate.

Count uses the same value editor as other particle numbers, so it can be a constant, a curve, a random range, or a random range between curves. Curved burst counts are sampled across the particle system duration. Cycles repeats the burst, Interval spaces those repeats, and Probability lets a burst sometimes skip for more natural variation.

Choosing A Shape

Start with the shape that matches the real source of the effect.

Use Point when particles come from one location. Good for pickups, stars, hit points, and muzzle flashes.

Use Line for edge-like sources. Good for waterfalls, platform dust along an edge, and stylized slashes.

Use Circle for 2D radial effects. Good for magic rings, explosions, and aura edges.

Use Rectangle for 2D areas. Good for rain zones, fog patches, and room-sized ambient motes.

Use Cone2D for directional 2D sprays. Good for sparks, dust, smoke jets, and directional impact feedback.

Use Sphere for 3D volume emission. Good for auras, floating motes, and ambient zones.

Use Hemisphere for one-sided 3D volume emission. Good for upward bursts, domes, and ground impacts.

Use Box for 3D rectangular volumes. Good for rain, snow, fog, and area effects.

Use Cone3D for directional 3D sprays. Good for sparks, smoke, exhaust, and muzzle effects.

Angle And Spread

Angle aims the emitter. Spread widens or narrows the possible directions.

Small spread creates a tight beam or spray. Large spread creates a loose spray. 360 creates a full radial burst.

Examples:

  • directed sparks: narrow cone
  • dust landing: medium upward cone
  • pickup sparkle: 360
  • rain: box shape with downward velocity or force
  • smoke: upward cone with low speed and turbulence

Radius, Thickness, Arc, And Emit From

Radius controls the size of circular, spherical, and cone sources. Radius Thickness controls whether particles fill the shape or stay near the outer edge. A thickness of 1 fills the available radius. A thickness near 0 creates edge or shell emission.

Arc controls how much of a circular or cone source participates. Arc mode controls how particles are distributed along that arc:

  • Random chooses a random point along the arc.
  • Loop walks around the arc over time.
  • Ping Pong moves back and forth across the arc.
  • Burst Spread spaces burst particles around the arc.

Emit From controls the source region. Use Base for the origin or cone base, Volume when particles should fill the shape, Shell when they should stay on the surface, and Edge when they should come from the perimeter.

Use shell or edge emission when the visible source is a surface:

  • magic ring
  • shield boundary
  • sphere aura edge
  • explosion shock ring

Use volume emission when particles should fill space:

  • fog
  • snow
  • dust cloud

Local Shape Transform

Shape position, rotation, and scale offset the emitter shape relative to the GameObject.

Use this when the owning GameObject's origin is not the effect source. For example, a character object may have its origin at the feet, while a magic aura should spawn around the hands.

You can also use a child GameObject as the particle emitter. That is often clearer when the source point is meaningful in the hierarchy.

Direction Controls

Align To Direction rotates particles to face their initial travel direction. This is useful for sparks, streaks, slashes, and other directional particles.

Randomize Direction blends the authored direction with random directions. Use small values to break up repeated motion without losing the overall shape.

Spherize Direction pushes particle motion away from the shape center. Use it for shockwaves, auras, burst rings, and outward explosions.

Randomize Position adds positional variation around the sampled shape point. Use it sparingly to soften mechanical-looking emitters.

Scene View Preview

Enable the Scene view FX toggle to preview particle systems while editing. When a selected object has a particle system, the Particle Effect floating window lets you play, pause, restart, stop, scrub playback time, change preview speed, show bounds, and isolate the selected system.

Practical Starting Values

Spark burst:

  • Shape: Cone2D or Cone3D
  • Spread: 20 to 45
  • Radius Thickness: 0 to 0.2
  • Emit From: Base or Edge
  • Align To Direction: enabled for streak textures
  • Lifetime: 0.2 to 0.6
  • Start speed: high
  • Burst Count: 16 to 64

Dust puff:

  • Shape: Cone2D or Hemisphere
  • Spread: 50 to 100
  • Lifetime: 0.5 to 1.2
  • Start speed: low to medium
  • Size grows and fades

Rain:

  • Shape: Rectangle or Box
  • Rate over time: high
  • Lifetime: based on fall distance
  • Force or velocity: downward
  • Renderer: stretched billboard or thin texture

Magic motes:

  • Shape: Circle or Sphere
  • Rate over time: low to medium
  • Lifetime: long
  • Start speed: low
  • Noise or velocity variation