Simulation Root

This compound is "central station" for ICE simulations, giving you easy access to many ports in which you can plug in nodes that are often used in simulations.

Plug this compound's Execute output into the ICETree node.

If you want to use the commands on the ICE toolbar, this compound must be connected in the object's ICE tree.

To quickly add the Simulation Root node to your ICE tree, right-click the ICETree node and select Insert Simulation Root. This replugs all the existing nodes to the correct ports on the Simulation Root node, then plugs this node into the ICETree node. This is similar to selecting the Insert Execute Node when building compounds.

TipYou can choose the Particles Simulation Inspect Simulation Root command to open up the selected point cloud or object's Simulation Root compound property editor without the ICE Tree view being open.

Versions of this Node

This node has two different versions:

  • 1.0 (No State Machine): a simple version that doesn't include all the State Machine ports. You may find this version useful if you don't want to use states, or you're using the State nodes separately.

    As well, the Lagoa nodes work only with version 1.0. If you're creating a Lagoa ICE tree from scratch, make sure to switch to version 1.0 before you start connecting the rest of the Lagoa nodes.

  • 2.0 (With State Machine): a full version that includes all ports described here. This the version used when you bring it into the ICE tree workspace. You may find this version useful if you want to use States without setting up a separate State Machine node: the State Machine node is incorporated into this node.

To change between versions, right-click on this node in the ICE tree and choose the one you want from the Version menu.

Category: Simulation

Output Ports: Execute


Plug in the Emit output from an Emit compound here.


Plug in the Execute output from the Add Forces compound here.


Plug in the Execute output from any node whose data you want to be executed at every frame.


Plug in the Simulate output from the Simulate Particles, Simulate Bullet Rigide Bodies, or Simulate Rigid Bodies node here.

State Machine

These ports appear only if you're using version 2.0 of the Simulation Root node. See above for more information about versions.

Use State Machine

Uses the state machine to process all nodes plugged into the ports in this section of the compound.

If this option is off, the states are not considered. This makes it easy to test the particle emission with or without the states.

Primary State

For more information on states, see ICE Particle States.

State ID

Gives the primary (initial) state a unique ID so that the particles in that state can be easily identified. If there are two states that have the same ID, only the state that is plugged in first into the State Machine will be evaluated.

Set Particle Color to State Color

Uses the State Color you define below as the display color for the particles. If this option is off, the particles are not displayed with this color. You can use the State Color as you're working with setting up the states, then turn off this option when you're finished setting up the states so that all particles are displayed with the same color.

State Color

Sets the particle's display color for the purpose of distinguishing the state to which it belongs.

Execute Once on Enter State

Executes the compound plugged in here only once when the trigger compound's value is reached.

Plug in a compound that can be used with States, then set the parameters in this compound's property editor to define the particle behavior. You can use compounds in the Surface Interaction, Goals, Spawning, Strands, or Motion Control groups. However, you can use any compound that can cause a change to particles, such as compounds in the Forces or Setters groups.


Defines the trigger, which is a compound that causes an effect to happen when its value is reached.

Plug in a compound from the Conditionals group to use as a trigger, such as Test Particle Age, then set its value. You can plug in any compound here that is a Boolean. When this compound's value is reached, the particles change to the next state that you define, and an action defined with another compound is executed.

Change State on Trigger

The state to which the particles will be transitioning when the trigger compound's value is reached. If you change to another state, you must create that State compound, give it a State ID, and set up its particle behavior. The particle stays in this state until it is forced to change to another state using this option.

Execute on Trigger

Executes whatever compound is plugged in here at the time that the trigger value is reached.

Next States

Max Iterations Per Frame

Defines the number of iterations per frame that the State compounds are evaluated. Keep this value low to reduce processing times, but you may need to set this higher for particles that move quickly from frame to frame.


State ID of the next state to execute.

Post Simulation


Plug in the Execute output from any node that you want to be executed after the simulation has been calculated.