Animate emitters and cells overview

By adding behaviors to a particle system’s emitter, or to the cells themselves, you can create sophisticated, organic animation that would be impossible to accomplish any other way. You can animate an emitter using behaviors designed specifically for particles, or by using Basic Motion, Parameter, or Simulation behaviors. You can also animate emitter parameters and cell parameters with keyframes.

Consider the following guidelines when animating a particle system:

  • Apply the Particles behaviors (Scale Over Life and Spin Over Life) to modify and animate the rotation and size of the particles over their lifetime. For details, see

  • Apply behaviors to particle cells or to the emitter to create even more varied effects (simulation behaviors can be especially effective). Any behavior that you apply to a cell is in turn applied to each particle the cell generates.

  • Apply a Simulation behavior to an emitter or another object in your project (an object that is not part of the particle system) to make particles interact with other objects in the project. For example, applying the Repel behavior to an object will cause particles to weave around that object.

  • Keyframe the Emitter Inspector parameters to modify the particle system’s overall characteristics over time, such as increasing or decreasing the size, speed, or lifetime of newly generated particles.

  • Keyframe the emitter’s Position parameter (in the Properties Inspector) to alter the position and geometric distribution of a particle system over time, such as creating a path of bubbles that follows an object onscreen. For more information on keyframing, see Animate parameters in the Inspector.

    Canvas showing particle system tracking another object
  • Use Motion Tracking behaviors to track an emitter to a moving object in a clip, or to apply existing tracking data in your project to an emitter. For more information about Motion Tracking behaviors, see Motion tracking overview.