Using Objects as ICE Particles

Substituting objects for particles allows you to use objects as part of a particle simulation. You can use any 3D object in place of particles to create many different effects. For example, you could use party streamers as particles to make a parade scene, cars to create a flow of traffic around a traffic circle, or characters to create a crowd scene. You can also loft instanced shapes along particle strands to create many different effects.

If you want to create animated actors as instances in a crowd simulation, see ICE CrowdFX for information.

What Do Instances Inherit from Their Master Object?

Instances are exact copies of their master object's geometry, including their materials (such as color and texture). This means that instances get their rendering information from their master object.

TipIf you want to use the particle color instead of the instanced geometry color for rendering, see Using the ICE Particle Color in the Render Tree.

If the geometry of the master object is animated (shape animation or a deformation), the instance also inherits that. See Using Animated Master Objects for details on using master objects with animated transformations.

What Do Instances Inherit from Their Particle?

Instances inherit these attributes that define the particle's movement and size: Position, Velocity, Orientation, and Size.

You could use a Randomize or Turbulize compound (such as Randomize Value by Range) to add some variation to these attributes for the instances. See ICE Particle Size, ICE Particle Speed, and ICE Particle Orientation for more ideas on which compounds to use for adding variation.

Collision Geometry for Instances

If you're using instances as particle shapes in collisions, different collision geometry is used for the instance geometry depending on the type of collision you're creating:

If the particles are rigid bodies using the Simulate Bullet Rigid Bodies node, you can choose between convex hull or bounding box approximation of the instance geometry. Convex hull more accurately reflects the shape, excluding any concavities. This is set in the Instance Shape or Set Instance Geometry node.
See Collision Geometry for Instanced Shapes for more information.
If the particles are rigid bodies using the Simulate Rigid Bodies node, a bounding box approximation of the instance geometry is used automatically.
If the particles are not rigid bodies and you're using a compound with surface interaction, such as Bounce Off Surface, a bounding sphere approximation of the instance geometry is used - see Motion Control and Surface Interaction Behavior for ICE Particles.

Hiding Instance Masters

If you want to keep the master objects in the scene, but you don't want to worry about them being displayed or rendered, you can simply move them out of the camera's view, or you can hide them by selecting the Instance Master Hidden option in each master object's Visibility property editor (Rendering tab).

If you hide the instance master in the standard way (such as by pressing H), they are not displayed when they are instantiated by the particles.

Caching Instances

If you're caching instanced geometry for ICE particles, make sure to keep the master object in the scene when writing or reading a cache file: even if the particles are cached, they still depend on the instance master to be present. The master object can be hidden, if you like.

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