Particular

Emitter > Layer Emitter Subgroup

This parameter group lets you emit particles from layers. The Emitter Type layer needs to be selected for this parameter group to be active.

Technical notes for Layer Emitters:

• When the Layer Emitter is keyframed and the keyframes are edited a lot, the cache sometimes works inappropriately. This manifests as jerkiness in the animation (the emitter jumps from one frame to the next). To get rid of erroneous frames from the cache, use Edit > Purge > Image Cache Memory, then re-render.
• The layer used as Layer Emitter must have Continuous Rasterize switched off in the timeline's Layer Switches.
• Shape layers are not supported as Layer Emitters.

Layer Pop-up

This control selects a comp layer that will emit particles.

Layer Sampling Pop-up

This control defines how layer information should be read.

• Particle Birth Time: This is the default setting. Each particle, when birthed, samples its image from the Layer Emitter and retains that image throughout its lifespan.
• Current Frame: This option samples the layer at the current frame.

Layer RGB Usage Pop-up

This control defines how to use the values sampled from the layer serving as the Layer Emitter.

• Lightness - Size: Particle size is affected by Layer Emitter lightness.
• Lightness - Velocity: Particle velocity is affected by Layer Emitter lightness. If lightness is less than 50%, the particle will emit backwards. If lightness is exactly 50%, velocity will be 0. Above 50%, particles will emit forwards.
• Lightness - Rotation: Particle rotation is affected by Layer Emitter lightness.
• RGB - Size Vel Rot: Particles get their size, velocity, and rotation from the Layer Emitter's red, green, and blue color channels.
• RGB - Particle Color: This is the default selection. Particles get their color from the Layer Emitter's red, green, and blue color channels.
• None: No values are used.
• RGB - Size Vel Rot + Col: Particle size, velocity, rotation, and color are affected by the Layer Emitter's red, green, and blue color channels.
• RGB - XYZ Velocity: Particles get their velocity from the Layer Emitter's red, green, and blue color channels.
• RGB - XYZ Velocity + Col: Particles get their velocity and color from the Layer Emitter's red, green, and blue color channels.