Emitter guide
Browse Emitter controls by UI section
An emitter supplies particle birth positions. Its controls appear in EMITTER for the selected system. Use them to create a stream, a fixed arrangement, or a burst. Entropy creates particles according to Emitter Behavior as time advances.
Choose when particles appear
| Emitter Behavior | Use it for |
|---|---|
| Continuous | An ongoing stream. Particles/sec sets the creation rate. |
| Static | A fixed particle field. Static particles do not age. |
| Burst | A one-shot release. Particle Count sets the total. Burst Frames spreads the release over time. |
| From Parent's Particles | A child that emits from living parent particles. The rate applies to each living parent particle. |
| On Parent Death | A child that emits when parent particles die. |
| From Parent Position | A child that emits from its parent's source position. |
Parent-based behaviors require a child system. See multiple systems.
For Burst, increase Burst Decay to put more of the release near the start. It changes the timing, not the total count. Restart the preview when you want to see the burst again.
Choose a source
| Emitter Shape | Source |
|---|---|
| Point | One source position. |
| Line | A line that can also guide particle travel. |
| Cylinder | A cylindrical region. |
| Sphere | A spherical region. |
| Box | A region with width, height, and depth. |
| Mesh | A three-dimensional surface from an OBJ file. OBJ is a file format for 3D models. |
| Light | After Effects Light layers selected by a name prefix. |
| Text | Letter shapes. Composer provides text and font controls; After Effects provides a source text layer. |
| Formula | A Wave, Spiral, or Lissajous curve. A Lissajous curve combines repeating motion along separate axes. |
| Mask | A mask path in After Effects. A mask is an outline attached to a layer. |
| Layer | An After Effects layer's image and transparency. |
Place and distribute particles
Position uses composition coordinates: X moves right, Y moves down, and Z moves deeper into the scene. Rotation turns the source around those axes.
Link source dimensions for uniform scaling, or adjust each axis separately. Sphere uses Emitter Size X as its diameter and ignores Y and Z.
Distribution chooses Fill, Edge, or Surface where supported. Edge and Surface have the same result on 3D shapes. Point and Line ignore this setting. Mask uses Emit From instead.
Spacing chooses random placement or a regular grid. Mesh surfaces use random placement. For a grid, set the counts along each axis. Stagger offsets alternate rows or rings; a half-cell offset makes a brick-like arrangement. Grid sampling can reduce positions around narrower parts of curved shapes.
Seed changes the repeatable random arrangement. Keep the seed when you want to compare another setting without also changing the random pattern.
Set starting motion
Velocity controls speed at birth. Speed variation gives particles different starting speeds. Spread controls the cone of starting directions: zero sends particles one way; 360 degrees sends them in all directions.
Source-motion inheritance adds emitter movement to newborn particles. Use it when an animated emitter should fling particles along its motion.
Emit from text or a mesh
Choose Text to use letter shapes. In Composer, enter the text and choose a font. Extrusion adds depth. Bevel controls shape the transition between the letter face and its sides. Increase bevel quality after the text shape is settled.
Choose Mesh and browse for an OBJ to emit from a model. Center the model if its authored origin puts it away from the emitter point. Emitter size still controls its scale.
Show Text or Show Source includes the solid source body in the rendered image. Turn it off to show only particles. EMITTER MATERIAL changes the source body. Particle material changes the emitted particles.
Emit from After Effects layers
For a Layer emitter, select the source layer. Its alpha channel—the image's transparency—controls where particles are born. Select Color Mode > From Layer to use its image colors.
For a Mask emitter, choose a path or enable All Masks. Path emits along the outline. Face (Closed Path) fills the interior. An open path falls back to outline emission.
For a Light emitter, set the name prefix that identifies source lights. Every matching light becomes a source. Enable the light-intensity count option if brighter lights should emit more particles.
Check these sources in After Effects. Composer does not contain your composition's live layer and light context.
Make particles follow a path
Line, Formula, and Mask sources provide path controls. A path can place particles at birth or steer them after birth.
- Choose Formula, then Spiral.
- Set the source length and spiral radii to make a visible curve.
- Match Emit Start and Emit End to create particles at one point on the path.
- Raise Follow Path above zero.
- Set Path Speed above zero to move forward, or below zero to move backward.
- Preview the motion. Particles should travel along the curve.
Follow Path applies a force. Other forces can still move particles away from the curve. Path Speed has no effect while Follow Path is zero.
Path Radius gives the stream thickness. Radius Aspect flattens it into a ribbon. Twist changes the ribbon's rotation along the path. Use the end behavior to let particles continue, loop, stop, or die at the end.
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